Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Theses/Dissertations

2020

University of Kentucky

Discipline
Keyword
Publication

Articles 1 - 30 of 91

Full-Text Articles in Engineering

Proof Of Concept For The Development Of A Ground Vibration Sensor System For Future Research In Blasting, John Meuth Jan 2020

Proof Of Concept For The Development Of A Ground Vibration Sensor System For Future Research In Blasting, John Meuth

Theses and Dissertations--Mining Engineering

Ground vibrations from blasting are one of the leading limitations to mining (underground and surface). There is a need for a low-cost scalable vibration monitoring system to conduct large scale ground vibration projects in the mining industry. Studies conducted on ground vibrations use any number of different sensors to obtain their data, the different sensor capabilities and methods for data processing lead to uncertainties in the research and regulations set for ground vibrations. Commercial Systems do not allow researchers to obtain raw output data, and the data processing procedures are not provided or disclosed for these systems. In order to …


Fourier Transform Infrared Spectroscopy (As A Rapid Method) Coupled With Machine Learning Approaches For Detection And Quantification Of Gluten Contaminations In Grain-Based Foods, Abuchi Godswill Okeke Jan 2020

Fourier Transform Infrared Spectroscopy (As A Rapid Method) Coupled With Machine Learning Approaches For Detection And Quantification Of Gluten Contaminations In Grain-Based Foods, Abuchi Godswill Okeke

Theses and Dissertations--Biosystems and Agricultural Engineering

Cross-contamination between food grains during harvesting, transportation, and/or food processing is still a major issue in the food industry. Due to cross-contact with gluten-rich grains (wheat, barley, and rye grains), gluten can get into food that’s naturally free from gluten and thus may not be safe for consumption for people susceptible to gluten-related disorders such as celiac disease, wheat allergy, gluten intolerance or sensitivity. The conventional method of gluten detection is cumbersome, time-consuming, and requires well-trained personnel. Therefore, there is a need for a rapid and equally effective technique to authenticate gluten contamination in foods. This research work explored the …


Microfiltration Membrane Pore Functionalization Approaches For Chloro-Organic Remediation To Heavy Metal Sorption, Mohammad Saiful Islam Jan 2020

Microfiltration Membrane Pore Functionalization Approaches For Chloro-Organic Remediation To Heavy Metal Sorption, Mohammad Saiful Islam

Theses and Dissertations--Chemical and Materials Engineering

Microfiltration polyvinylidene fluoride (PVDF) membranes have distinct advantage for open structure in terms of high internal surface area and ease of access in the pore domain. Functionalization of PVDF membranes with different functional groups (-COOH, -OH, -SH) enables responsive (pH, temperature) properties to membrane, tuning of effective pore size, controlling permeate flux. PVDF microfiltration membrane functionalization with suitable responsive polymer such as poly acrylic acid (PAA) to incorporate carboxyl (-COOH) group enables further modification of functionalized PAA-PVDF membranes for different application ranging from catalysis, bio reactor to heavy metal sorption platform. As a catalytic reactor bed, this PAA-PVDF membranes are …


Holistic Resilience Quantification Framework Of Rural Communities, Amanda Melendez Jan 2020

Holistic Resilience Quantification Framework Of Rural Communities, Amanda Melendez

Theses and Dissertations--Civil Engineering

Communities need to prepare for anticipated hazards, adapt to varying conditions, and resist and recover rapidly from disturbances. Protecting the built environment from natural and man-made hazards and understanding the impact of these hazards helps allocate resources efficiently. Recently, an indicator-based and time-dependent approach was developed for defining and measuring the functionality and disaster resilience continuously at the community level. This computational method uses seven dimensions that find qualitative characteristics and transforms them into quantitative measures. The proposed framework is used to study the resilience of rural communities’ subject to severe flooding events. Harlan County in the Appalachian region is …


A Framework For Heterologous Biosynthesis Of Natural Products In Mammalian Cells Via Polymer-Mediated Transfections, Logan Warriner Jan 2020

A Framework For Heterologous Biosynthesis Of Natural Products In Mammalian Cells Via Polymer-Mediated Transfections, Logan Warriner

Theses and Dissertations--Chemical and Materials Engineering

With the promise to treat a multi-faceted list of serious inherited and acquired diseases, such as cancer, neurodegenerative and infectious diseases, and inherited genetic indications, gene therapy has continued to push the boundaries of traditional medicine since its earliest implementation. While much progress has been made, clinical success has largely remained elusive. Immunogenicity, difficulty producing commercially relevant quantities, and having a limited genetic payload still limits the ability of viruses to act as directed delivery agents for genetic material. As such, researchers have turned to cationic synthetic materials as a means of delivering nucleic acids, which can circumvent the immune …


The Effect Of Delay And Sequence On Blasting Fragmentation Results, Tristan Worsey Jan 2020

The Effect Of Delay And Sequence On Blasting Fragmentation Results, Tristan Worsey

Theses and Dissertations--Mining Engineering

Blasters use the delay between charges and the firing sequence of the explosive charges to help reduce vibrations and achieve the desired fragmentation. Although delay and sequence are recognized as very important for vibrations and fragmentation, only vibration models consider timing as a variable in the prediction tool, without any known model for fragmentation prediction based on the delay sequence. Of the few fragmentation models available, very few take delay into account and do not give guidance on row delay and/or sequence selections. With the invention of electronic detonators in 1984, there are new avenues to explore with sequence and …


Design And Analysis Of A Pavement Marker Detection System, Timothy L. Johnson Ii Jan 2020

Design And Analysis Of A Pavement Marker Detection System, Timothy L. Johnson Ii

Theses and Dissertations--Civil Engineering

Personal injuries and property damage due to the failure of snow-plowable pavement markers which detach from pavement surfaces has led to the development of new all-plastic pavement markers which are located entirely below the planar surface of the pavement. The new all-plastic design pushes existing solutions used to avoid striping over highway reflectors into obsolescence since current solutions operate using electromagnets to sense the metal housings of snow-plowable pavement markers. A replacement solution is currently sought by the highway maintenance industry and three different marker detection methods were developed and tested on real-world highways with both new and aging pavement …


Effects Of Hydrologic Variations On Hydraulic And Deformational Characteristics Of Unsaturated Soils, Majid Mahmoodabadi Jan 2020

Effects Of Hydrologic Variations On Hydraulic And Deformational Characteristics Of Unsaturated Soils, Majid Mahmoodabadi

Theses and Dissertations--Civil Engineering

Constitutive models that can provide useful insight into the deformational mechanism induced by hydrologic variations are vital for design and analysis of structures where unsaturated regime predominates. An accurate description of unsaturated soils’ behavior not only requires a vigorous constitutive model, but essentially is achievable using real-time mechanical (e.g. small-strain shear modulus) and hydrologic data sets. The main objective of this research was to develop a robust constitutive scheme that is compatible to quick fluctuations in hydrologic conditions.

The first step towards accomplishing this aim involved proposing a novel methodology to estimate the small-strain shear modules with respect to the …


Molten Aluminum Capillary Hole-Filling, Cheng-Nien Yu Jan 2020

Molten Aluminum Capillary Hole-Filling, Cheng-Nien Yu

Theses and Dissertations--Mechanical Engineering

The presence of micrometeoroids and space debris in open space raises the question of a mitigation of the damage caused by a possible impact on the man-made structures such as space shuttles, satellites, and the International Space Station. A method achieving metallic sealed hole would be of an interest for development. This dissertation studies a surface tension driven capillary filling/sealing phenomenon in a controlled atmosphere brazing process of aluminum. The filled vs. non-filled results are predictable using minimization of energy, which shows that the outcomes depend heavily on prescribed configurations of the hole. Equilibrium models show excellent agreement with experimental …


Bacterial Cell Wall Characterization Via Atomic Force And Confocal Microscopy, Joree Sandin Jan 2020

Bacterial Cell Wall Characterization Via Atomic Force And Confocal Microscopy, Joree Sandin

Theses and Dissertations--Mechanical Engineering

Poor oral hygiene is a severe global health issue, with about 44% of the Earth’s population suffering from untreated tooth decay, accounting for over $100 billion dollars spent on dental services per year in the United States, alone. Manual treatments, such as brushing, flossing, or swishing with antiseptic rinse are the main ways to alleviate harmful bacteria that cause these oral health problems. Streptococcus mutans (S. mutans) is a group of highly antibiotic, Gram-positive bacteria that heavily contribute to oral cavities, plaque build-up, and potential loosening or loss of dental implants if a biofilm develops. Currently, the mechanism …


Disassemble/Analyze/Assemble: How A Hands-On Engineering Project Affects High School Girls' Science/Engineering Self-Efficacy, Interest And Career Considerations, Jennifer Corbett Ferguson Jan 2020

Disassemble/Analyze/Assemble: How A Hands-On Engineering Project Affects High School Girls' Science/Engineering Self-Efficacy, Interest And Career Considerations, Jennifer Corbett Ferguson

Theses and Dissertations--Education Sciences

Engineering education as part of the K-12 curriculum can be an effective instructional tool and its benefits include improved science and mathematical achievement as well as an increased interest and understanding of the engineering field, especially for female students. However, there is a serious lack of research-based engineering curriculum being used at the middle and high school levels and lessons most often rely on building or construction competitions. Over the past decade or two, many well-known colleges have implemented a reverse engineering instructional unit known as Disassemble/Analyze/Assemble projects within their introductory engineering courses. These units have been shown to improve …


Electrophoresis In Heterogeneous Hydrogels And Applications In Surface Patterning, Ning Ge Jan 2020

Electrophoresis In Heterogeneous Hydrogels And Applications In Surface Patterning, Ning Ge

Theses and Dissertations--Mechanical Engineering

The creation of chemical micropatterns on surfaces makes it possible to add unique chemical functionality to surfaces, modifying properties such as wettability, or even adding the ability to selectively bind other molecules. The creation of biochemical surface patterning in particular is useful in a variety of fields including tissue engineering and highthroughput drug screening. There are many existing surface patterning techniques which focus on precise control over the patterned geometry, even down to submicron scale features, but they do not allow local control over chemical concentration. So the results are high resolution patterns with binary concentration. There are also existing …


Development And Application Of Novel Sound Absorbers, Weiyun Liu Jan 2020

Development And Application Of Novel Sound Absorbers, Weiyun Liu

Theses and Dissertations--Mechanical Engineering

The sound absorbers in most common use today are porous materials like fibers and foams. This work examines three alternatives to porous absorbers: microperforated panels, acoustic fabrics, and additively manufactured absorbers. The research is a combination of design, measurement and characterization of their properties, and analysis.

Microperforated panels are thin metallic or plastic panels with sub-millimeter size holes or perforations. Sound absorption can be tuned by adjusting the spacing between the panel and a cavity behind the panel. Several different configurations were considered where the geometry behind the panel was divided up into channels of varying length and cross-sectional area. …


Resource Efficient Design Of Quantum Circuits For Cryptanalysis And Scientific Computing Applications, Edgard Munoz-Coreas Jan 2020

Resource Efficient Design Of Quantum Circuits For Cryptanalysis And Scientific Computing Applications, Edgard Munoz-Coreas

Theses and Dissertations--Electrical and Computer Engineering

Quantum computers offer the potential to extend our abilities to tackle computational problems in fields such as number theory, encryption, search and scientific computation. Up to a superpolynomial speedup has been reported for quantum algorithms in these areas. Motivated by the promise of faster computations, the development of quantum machines has caught the attention of both academics and industry researchers. Quantum machines are now at sizes where implementations of quantum algorithms or their components are now becoming possible. In order to implement quantum algorithms on quantum machines, resource efficient circuits and functional blocks must be designed. In this work, we …


Numerical Approximation Of The Ground Reaction And Support Reaction Curves For Underground Limestone Mines, Jesus Castillo Gomez Jan 2020

Numerical Approximation Of The Ground Reaction And Support Reaction Curves For Underground Limestone Mines, Jesus Castillo Gomez

Theses and Dissertations--Mining Engineering

Pillar stability has been a matter of study for the last 70 years. The determination of pillar strength had taken different solutions and approaches over that time. This research has led to numerous empirical formulations that have reduced the number of pillar failures worldwide. However, new numerical approaches are being studied. In the last 20 years, the Ground Reaction Curve concept has been examined as a way of understanding the convergence of the rock-mass. Although the Ground Reaction Curve was first introduced in the civil tunneling industry, several authors have introduced the Ground Reaction Curve concept as an approach for …


Assessment Of White Matter Hyperintensity, Cerebral Blood Flow, And Cerebral Oxygenation In Older Subjects Stratified By Cerebrovascular Risk, Ahmed A. Bahrani Jan 2020

Assessment Of White Matter Hyperintensity, Cerebral Blood Flow, And Cerebral Oxygenation In Older Subjects Stratified By Cerebrovascular Risk, Ahmed A. Bahrani

Theses and Dissertations--Biomedical Engineering

Objective: Cerebrovascular disease (CVD) is the fifth most common cause of mortality in the United States. Diagnosis of CVD at an early stage is critical for optimal intervention designed to prevent ongoing and future brain injury. CVD is commonly associated with abnormalities of the cerebral microvasculature leading to tissue dysfunction, neuronal injury and death, and resultant clinical symptoms, which in turn, further impacts cerebral autoregulation (CA). This series of studies aims to test the hypothesis that white matter hyperintensities (WMH) and cerebral hemodynamics (quantified by magnetic resonance imaging (MRI) and an by innovative hybrid near-infrared diffuse optical instrument) can be …


Noncontact Multiscale Diffuse Optical Imaging Of Deep Tissue Hemodynamics In Animals And Humans, Siavash Mazdeyasna Jan 2020

Noncontact Multiscale Diffuse Optical Imaging Of Deep Tissue Hemodynamics In Animals And Humans, Siavash Mazdeyasna

Theses and Dissertations--Biomedical Engineering

Blood flow (BF) impacts the delivery of oxygen and nutrients to tissues and the removal of metabolic byproducts from tissues. Imaging of BF distributions helps characterize many diseases associated with tissue hypoxia/ischemia. The purpose of this study was to develop and validate a novel, noninvasive, noncontact, high-density camera-based speckle contrast diffuse correlation tomography (scDCT) device for use in both animal and human studies. The scDCT uses a galvo-mirror to remotely deliver the focused point near-infrared light to source positions and a sensitive 2D camera to quantify spatial diffuse speckle fluctuations, resulting from the movement of red blood cells in deep …


The Relationship Between Roadway Homogeneity And Network Coverage For Network Screening, Riana Tanzen Jan 2020

The Relationship Between Roadway Homogeneity And Network Coverage For Network Screening, Riana Tanzen

Theses and Dissertations--Civil Engineering

In the context of transportation safety engineering, network screening is a method of identifying and prioritizing high-risk locations for potential safety investment. Since its release, the Highway Safety Manual (HSM) has facilitated the adoption of Safety Performance Functions (SPF) to predict the number of crashes for the network screening of any facility type. The predictive model becomes more reliable when developed from crash data with homogeneous roadway segments and this homogeneity can be attained by applying specific geometric attributes to the dataset. The caveat to this method is the requirement of adjustment factors (AFs) to adjust the predicted estimate for …


Estimating Free-Flow Speed With Lidar And Overhead Imagery, Armin Hadzic Jan 2020

Estimating Free-Flow Speed With Lidar And Overhead Imagery, Armin Hadzic

Theses and Dissertations--Computer Science

Understanding free-flow speed is fundamental to transportation engineering in order to improve traffic flow, control, and planning. The free-flow speed of a road segment is the average speed of automobiles unaffected by traffic congestion or delay. Collecting speed data across a state is both expensive and time consuming. Some approaches have been presented to estimate speed using geometric road features for certain types of roads in limited environments. However, estimating speed at state scale for varying landscapes, environments, and road qualities has been relegated to manual engineering and expensive sensor networks. This thesis proposes an automated approach for estimating free-flow …


Automated Testing And Bug Reproduction Of Android Apps, Yu Zhao Jan 2020

Automated Testing And Bug Reproduction Of Android Apps, Yu Zhao

Theses and Dissertations--Computer Science

The large demand of mobile devices creates significant concerns about the quality of mobile applications (apps). The corresponding increase in app complexity has made app testing and maintenance activities more challenging. During app development phase, developers need to test the app in order to guarantee its quality before releasing it to the market. During the deployment phase, developers heavily rely on bug reports to reproduce failures reported by users. Because of the rapid releasing cycle of apps and limited human resources, it is difficult for developers to manually construct test cases for testing the apps or diagnose failures from a …


Understanding And Mitigating The Electrochemical-Mechanical Degradation Of High Capacity Battery Electrodes, Dingying Dang Jan 2020

Understanding And Mitigating The Electrochemical-Mechanical Degradation Of High Capacity Battery Electrodes, Dingying Dang

Theses and Dissertations--Chemical and Materials Engineering

Lithium-ion batteries (LIBs) with high energy density and cycling stability play a critical role in developing electric vehicle (EV) and grid energy storage techniques. The electrochemical performance of LIBs can be improved by using high capacity positive (e.g., LiNi1/3Mn1/3Co1/3O2, i.e., NMC111) and negative (e.g., silicon) electrodes; both, however, experience severe electrochemical-mechanical degradation caused by the lithiation/delithiation induced volume changes. Understanding mechanical degradation mechanisms and their relationships with the capacity fading of electrodes is important for improving the cycling stability of electrodes as well as optimizing the design of electrodes with high capacity …


Polymeric Nanocomposite Membranes With Phosphorene Based Pore Fillers For Fouling Control, Joyner Eke Jan 2020

Polymeric Nanocomposite Membranes With Phosphorene Based Pore Fillers For Fouling Control, Joyner Eke

Theses and Dissertations--Chemical and Materials Engineering

Phosphorene is a two-dimensional material exfoliated from bulk phosphorus. Specifically, relevant to the field of membrane science, the band gap of phosphorene provides it with potential photocatalytic properties, which could be explored in making reactive membranes able to control the accumulation of compounds on the surface during filtration, or fouling. Another reason phosphorene is a promising candidate as a membrane material additive is due to its catalytic properties which can potentially destroy foulants on the membrane surface.

The first goal of this study was to develop an innovative and robust membrane able to control and reverse fouling with minimal changes …


Knee Joint Loading Following Anterior Cruciate Ligament Reconstruction: Link To Patient Reported Outcomes And A Novel Method To Monitor With Wearable Sensors, Alex Spencer Jan 2020

Knee Joint Loading Following Anterior Cruciate Ligament Reconstruction: Link To Patient Reported Outcomes And A Novel Method To Monitor With Wearable Sensors, Alex Spencer

Theses and Dissertations--Kinesiology and Health Promotion

Recovery from anterior cruciate ligament reconstruction (ACLR) commonly results in undesirable physical and patient-reported outcomes (PROs). Identification of modifiable factors such as knee contact force (KCF) early in rehabilitation that can improve these outcomes is important due to the rapid decrease in function, quality of life, and joint health in this population. Additionally, if noninvasive measurement of KCFs outside of a traditional laboratory were possible, clinicians could optimize patient treatment with personalized care. Therefore, there are two primary aims to this thesis: 1) quantify the link between KCF and PROs which measure pain, ability to perform activities of daily living, …


Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm Jan 2020

Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm

Theses and Dissertations--Chemistry

Halide perovskites have generated tremendous interest as low-cost semiconductors for optoelectronics, such as photovoltaics, lasers, and light emitting diodes due to their extraordinary optical and transport properties. Perovskite photovoltaics in particular have demonstrated a meteoric rise in power conversion efficiencies and drawn considerable interest as a next-generation solar energy technology. The rapid development has centered around lead-based derivatives, and concerns regarding the toxicity of lead has sparked interest in low toxicity and more environmentally friendly perovskite derivatives. In this regime tin (Sn) is regarded as a prominent alternative owing to the ideal bandgap and reduced toxicity exhibited by Sn-halide perovskites. …


Adaptive Tracking Controller For Real-Time Hybrid Simulation, Alejandro Palacio-Betancur Jan 2020

Adaptive Tracking Controller For Real-Time Hybrid Simulation, Alejandro Palacio-Betancur

Theses and Dissertations--Civil Engineering

Real-time hybrid simulation (RTHS) is a versatile and cost-effective testing method for studying the performance of structures subjected to dynamic loading. RTHS decomposes a structure into partitioned physical and numerical sub-structures that are coupled together through actuation systems. The sub-structuring approach is particularly attractive for studying large-scale problems since it allows for setting up large-scale structures with thousands of degrees of freedom in numerical simulations while specific components can be studied experimentally.The actuator dynamics generate an inevitable time delay in the overall system that affects the accuracy and stability of the simulation. Therefore, developing robust tracking control methodologies are necessary …


Nanostructured Device Designs For Enhanced Performance In Cds/Cu2S Heterojunction Solar Cells, Benjamin Wells Jan 2020

Nanostructured Device Designs For Enhanced Performance In Cds/Cu2S Heterojunction Solar Cells, Benjamin Wells

Theses and Dissertations--Electrical and Computer Engineering

Nanostructured CdS/Cu2S devices have been simulated using SCAPS-1D to demonstrate enhanced performance over traditional planar device structures. Two designs were examined: a nanowire CdS/planar Cu2S device and a nanowire CdS/nanowire Cu2S device. The addition of nanowires to a device had been previously demonstrated to improve device performance in a nanowire CdS/planar CdTe device by decreasing the amount of light absorbed by the CdS window layer, thus allowing more light to reach the absorber layer. Additionally, the total number of interface states can be greatly reduced due to the decreased total surface area between the window and absorber layers. The nanowire …


Fault Identification On Electrical Transmission Lines Using Artificial Neural Networks, Christopher W. Asbery Jan 2020

Fault Identification On Electrical Transmission Lines Using Artificial Neural Networks, Christopher W. Asbery

Theses and Dissertations--Electrical and Computer Engineering

Transmission lines are designed to transport large amounts of electrical power from the point of generation to the point of consumption. Since transmission lines are built to span over long distances, they are frequently exposed to many different situations that can cause abnormal conditions known as electrical faults. Electrical faults, when isolated, can cripple the transmission system as power flows are directed around these faults therefore leading to other numerous potential issues such as thermal and voltage violations, customer interruptions, or cascading events. When faults occur, protection systems installed near the faulted transmission lines will isolate these faults from the …


Rapid Prototyping Of Nanostructures With Electron Beam Induced Processing, Samaneh Esfandiarpour Jan 2020

Rapid Prototyping Of Nanostructures With Electron Beam Induced Processing, Samaneh Esfandiarpour

Theses and Dissertations--Electrical and Computer Engineering

Focused electron beam induced processing (FEBIP) is a nano-scale fabrication technique that allows the direct deposition of functional materials. However, it suffers from significant drawbacks, such as high cost, low speed, unavailable precursors for many materials and low purity of deposits. Liquid-phase focused electron beam induced processes (LP-FEBIP) are being investigated due to the potential benefits over the gas phase technique. In this method, deposition or etching occurs at the interface between a substrate and a bulk liquid. In this work, electron beam induced deposition of copper nanostructures from aqueous solutions of copper sulfate is demonstrated. The addition of sulfuric …


Integration Of Large Pv Power Plants And Batteries In The Electric Power System, Oluwaseun M. Akeyo Jan 2020

Integration Of Large Pv Power Plants And Batteries In The Electric Power System, Oluwaseun M. Akeyo

Theses and Dissertations--Electrical and Computer Engineering

The declining cost of renewables, the need for cleaner sources of energy, and environmental protection policies have led to the growing penetration of inverter-based resources such as solar photovoltaics (PV), wind, and battery energy storage systems (BESS) into the electric power system. The intermittent nature of these resources poses multiple challenges to the power grid and substantial changes in the conventional generation and electrical power delivery practices will be required to accommodate the large penetration of these renewable power plants. The impact of large solar PV penetration on both generation and transmission systems, and the use of BESS to mitigate …


Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle Jan 2020

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle

Theses and Dissertations--Chemistry

This project was motivated by an in situ heating experiment in the transmission electron microscope (TEM) in which gold (Au) nanoparticles were observed to dissolve tin dioxide (SnO2) nanowires (NWs) under vacuum. The explanation for this observation was that the high-temperature and low-pressure environment of the TEM caused the reverse reaction of the well-known vapor-liquid-solid (VLS) method commonly used to grow NWs. In the VLS process, a metal catalyst absorbs reactant vapor until it becomes supersaturated. The precipitation of the NW occurs at the liquid-solid interface, which ceases when there is no longer reactant vapor, and the diameter of the …