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Full-Text Articles in Engineering

Nanomechanics Of Electrospun Nanofibres For Tissue Engineering Of The Tympanic Membrane, Sara Makaremi Dec 2012

Nanomechanics Of Electrospun Nanofibres For Tissue Engineering Of The Tympanic Membrane, Sara Makaremi

Electronic Thesis and Dissertation Repository

The Tympanic Membrane (TM), also known as the eardrum, includes layers of organized collagen nanofibres which play an essential role in sound transmission. Perforations that are caused by infection or accident must be repaired in order to restore hearing. Tympanoplasty is performed using grafts that are prepared from bladder, cartilage, temporal fascia and cadaveric skin. However, since mechanical properties of these grafts do not match those of the original TM, normal hearing is not fully restored. The goal of this study is to develop nanofibrous scaffolds for tissue engineering of the TM in order to circumvent the complications addressed with …


Integrated Fiber Electrospinning: Creating Spatially Complex Electrospun Scaffolds With Minimal Delamination, Casey Grey Aug 2012

Integrated Fiber Electrospinning: Creating Spatially Complex Electrospun Scaffolds With Minimal Delamination, Casey Grey

Theses and Dissertations

Tissue engineering scaffolds come in many shapes and sizes, however, due to difficulty manufacturing the microstructure architecture required in tissue engineering, most scaffolds are architecturally non-dynamic in nature. Because the microstructural architecture of all biological tissues is inherently complicated, non-dynamic tissue engineering scaffolds tend to be a poor platform for tissue regeneration. The current method for manufacturing dynamic tissue engineering scaffolds involves electrospinning successive layers of different fibers, an approach that exhibits no fiber transition between layers and subsequent delamination problems. In this study we aim to address the design challenges of tissue engineering scaffolds through our novel integrated fiber …


Preparation And Characterization Of A Self-Crimp Side-By-Side Bicomponent Electrospun Material, Yang Han Aug 2012

Preparation And Characterization Of A Self-Crimp Side-By-Side Bicomponent Electrospun Material, Yang Han

Theses and Dissertations

Bicomponent composite fibers have been widely used in the textile industry and are gaining increasing attention on biomedical applications. In this research, polycaprolactone/poly (lactic acid) side-by-side bicomponent fibers were created for the application of a biodegradable scaffold. The side-by-side structure endowed the fiber with self-crimps when it was processed under certain conditions. This material was produced by electrospinning and collected on a high speed rotating mandrel to get highly oriented fibers. A mechanical stretch at the same direction was done followed by a wet heat treatment for polymer retraction. Crimped fibers were demonstrated by scanning electron microscopy. The quantitative porosity …


2d Modeling Of Forcespinning™ Nanofiber Formation With Experimental Study And Validation, Simon Padron Aug 2012

2d Modeling Of Forcespinning™ Nanofiber Formation With Experimental Study And Validation, Simon Padron

Theses and Dissertations - UTB/UTPA

A newly developed method of producing nanofibers, called Forcespinning™, has proven to be a viable alternative to mass produce nanofibers. Forcespinning™ utilizes centrifugal forces which allow for a host of new materials to be processed into nanofibers while also providing a significant increase in yield and ease of production. To improve and enhance the Forcespinning™ production method, a 2D computational Forcespinning™ fluid dynamics model is developed. Three computer models, namely time-independent and time-dependent inviscid models and a viscous model are obtained and the influences of various parameters on Forcespinning™ fiber formation are obtained. This work also presents a detailed explanation …


Development Of Magnetic Fabrics With Tunable Hydrophobicity, Thu Ho Jul 2012

Development Of Magnetic Fabrics With Tunable Hydrophobicity, Thu Ho

Theses and Dissertations

Polystyrene (PS) fiber mats incorporating iron (Fe) particles were fabricated by electrospinning and the hydrophobicity of the resulting magnetic fabrics was investigated with and without an applied magnetic field. The results show that the hydrophobicity (as measured using water droplet contact angle) increases in the presence of a magnetic field and the hysterisis in the advancing/receding contact angle (a measure of the stickiness of the surface) decreases in the presence of a magnetic field. It is also shown that the contact angle and hysterises increase with decreasing fiber diameter and mat thickness.


Design Of Experimentation To Systematically Determine The Interaction Between Electrospinning Variables And To Optimize The Fiber Diameter Of Electrospun Poly (D, L-Lactide-Co-Glycolide) Scaffolds For Tissue Engineered Constructs, Yvette S. Castillo Jun 2012

Design Of Experimentation To Systematically Determine The Interaction Between Electrospinning Variables And To Optimize The Fiber Diameter Of Electrospun Poly (D, L-Lactide-Co-Glycolide) Scaffolds For Tissue Engineered Constructs, Yvette S. Castillo

Master's Theses

Cardiac disease causes approximately a third of the deaths in the United States. Furthermore, most of these deaths are due to a condition termed atherosclerosis, which is a buildup of plaque in the coronary arteries, leading to occlusion of normal blood flow to the cardiac muscle. Among the methods to treat the condition, stents are devices that are used to restore normal blood flow in the atherosclerotic arteries. Before advancement can be made to these devices and changes can be tested in live models, a reliable testing method that mimics the environment of the native blood vessel is needed. Dr. …


The Incorporation Of Electrohydrodynamics And Other Modifications Into A Dry Spinning Model To Develop A Theoretical Framework For Electrospinning, Yuki Imura May 2012

The Incorporation Of Electrohydrodynamics And Other Modifications Into A Dry Spinning Model To Develop A Theoretical Framework For Electrospinning, Yuki Imura

Dissertations

The objective of this research was the development of a mathematical model of the electrospinning process using dry spinning modeling principles as a basis. This model is directed at the identification of parameters which influence final fiber characteristics, e.g., solvent concentration, temperature, spin line tension, and electric field. Preliminary computer simulations were performed; however, the generated data was inconclusive and was determined to be due in part to the complexity of the modeled system and the subsequent computational difficulties encountered. Although a comprehensive computational model of the electrospinning process has not yet been demonstrated, the theoretical development that was undertaken …


Characterization Of Superhydrophobic Surfaces Fabricated Using Ac-Electrospinning And Random Particle Deposition, Mohamed Samaha Jr. May 2012

Characterization Of Superhydrophobic Surfaces Fabricated Using Ac-Electrospinning And Random Particle Deposition, Mohamed Samaha Jr.

Theses and Dissertations

Surfaces with static contact angle greater than 150 degrees are typically classified as superhydrophobic. Such coatings have been inspired by the lotus leaf. As water flows over a superhydrophobic surface, "slip effect" is produced resulting in a reduction in the skin-friction drag exerted on the surface. Slip flow is caused by the entrapment of a layer of air between water and the surface. Superhydrophobicity could be utilized to design surfaces for applications such as energy conservation, noise reduction, laminar-to-turbulent-transition delay, and mixing enhancement. A popular method of manufacturing a superhydrophobic surface is microfabrication in which well-designed microgrooves and/or poles are …


Electrospun Polycaprolactone Nanofiber Scaffolds For Tissue Engineering, Andreas Haukas May 2012

Electrospun Polycaprolactone Nanofiber Scaffolds For Tissue Engineering, Andreas Haukas

Graduate Theses and Dissertations

Stem cell and tissue engineering offer us with a unique opportunity to research and develop new therapies for treating various diseases that are otherwise incurable using traditional medicines. However, development of these new therapies replies upon the establishment of in vitro cell culture and differentiation systems that mimic in vivo microenvironments required for cell-cell and cell-ECM interaction. The development of these cell culture systems depends upon the identification of appropriate biomaterials and cell sources. Biomaterials should be carefully selected and fabricated into scaffolds for supporting cell growth and differentiation. In this study, we explored the fabrication of 3D electrospun nanofiber …


Three Dimensional In Vitro Model Of Head And Neck Squamous Cell Carcinoma, Anna Bulysheva Apr 2012

Three Dimensional In Vitro Model Of Head And Neck Squamous Cell Carcinoma, Anna Bulysheva

Theses and Dissertations

Head and neck squamous cell carcinomas (HNSCC) are among the leading causes of cancer related deaths throughout the world. The survival rate for this type of cancer is extremely low and has not changed significantly in recent decades. There is an imperative need to study tumor progression in a representative model in order to generate more knowledge about this disease as well as develop more effective treatment options. Multiple methods already exist for studying HNSCC and other types of cancers, including in vitro and in vivo models. Although in vivo models are more representative of the human carcinomas in terms …


Insights Into The Power Law Relationships That Describe Mass Deposition Rates During Electrospinning, Jonathan J. Stanger, Nick Tucker, Simon Fullick, Mathieu Sellier, Mark P. Staiger Feb 2012

Insights Into The Power Law Relationships That Describe Mass Deposition Rates During Electrospinning, Jonathan J. Stanger, Nick Tucker, Simon Fullick, Mathieu Sellier, Mark P. Staiger

Jonathan J Stanger

This work explores how in electrospinning, mass deposition rate and electric current relate to applied voltage and electrode separation, factors give a range of applied electric fields. Mass deposition rate was measured by quantifying the rate of dry fibre deposited over time. Electric current was measured using a current feedback from the high voltage supply. The deposition of fibre was observed to occur at a constant rate for deposition times of up to 30 min. Both the mass deposition rate and electric current were found to vary with the applied voltage according to a power law. The relationship between the …


Manipulation Of Electrospun Fibres In Flight: The Principle Of Superposition Of Electric Fields As A Control Method, Nurfaizey A. Hamid, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Mark P. Staiger Jan 2012

Manipulation Of Electrospun Fibres In Flight: The Principle Of Superposition Of Electric Fields As A Control Method, Nurfaizey A. Hamid, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Mark P. Staiger

Jonathan J Stanger

This study investigates the magnitude of movement of the area of deposition of electrospun fibres in response to an applied auxiliary electric field. The auxiliary field is generated by two pairs of rod electrodes positioned adjacent and parallel to the line of flight of the spun fibre. The changes in shape of the deposition area and the degree of movement of the deposition area are quantified by optical scanning and image analysis. A linear response was observed between the magnitude of movement of the deposition area and voltage difference between the auxiliary and deposition electrodes. A squeezing effect which changed …


Raman And Infrared Study Of Electrospun Plla/Pcl Nanofiber Blends For Use In Tissue Engineering, Jose Luis Enriquez Carrejo Jan 2012

Raman And Infrared Study Of Electrospun Plla/Pcl Nanofiber Blends For Use In Tissue Engineering, Jose Luis Enriquez Carrejo

Open Access Theses & Dissertations

Recently, the biomedical engineering field has developed at a very fast pace as improved techniques and materials become available to promote its growth. Consequently, the research in polymeric biomaterials has been highly stimulated by this trend. The goal of the current research is to demonstrate the usefulness of the Raman scattering, Raman mapping, and infrared absorption spectroscopies to tissue engineering, by spectroscopically characterizing blends of PLLA and PCL polymers, which were prepared by electrospinning with and without cell addition. The proposed use of these blends is as primary biomaterials in biodegradable scaffolds used in tissue engineering. Both Raman and infrared …


Regeneration Of Electrospun Bioresorbable Vascular Grafts: A Phenomenon Associated With Vascular Graft Properties And Macrophage Phenotypes (M1/M2), Koyal Garg Jan 2012

Regeneration Of Electrospun Bioresorbable Vascular Grafts: A Phenomenon Associated With Vascular Graft Properties And Macrophage Phenotypes (M1/M2), Koyal Garg

Theses and Dissertations

Macrophages (MФ) and mast cells are important cell types in the context of tissue remodeling and regeneration. Mast cells participate in the early stages of wound healing and modulate the acute inflammatory responses to biomaterials. Mast cells can secrete a myriad of different cytokines by the process of degranulation; the process of regulated secretion in which preformed contents stored in their granules are rapidly released by exocytosis. Some of these cytokines such as IL-4, IL-13 and TNF-α can modulate the MФ phenotype. Macrophages (MΦ) are innate immune cells, crucial for tissue homeostasis, presentation of foreign and self-antigens following infection/injury, pathogen …


Electrospun Carbon Nanofibers Decorated With Various Amounts Of Electrochemically-Inert Nickel Nanoparticles For Use As High-Performance Energy Storage Materials, Liwen Ji, Zhan Lin, Mataz Alcoutlabi, Ozan Toprakci, Yingfang Yao, Guanjie Xu, Shuli Li, Xiangwu Zhang Jan 2012

Electrospun Carbon Nanofibers Decorated With Various Amounts Of Electrochemically-Inert Nickel Nanoparticles For Use As High-Performance Energy Storage Materials, Liwen Ji, Zhan Lin, Mataz Alcoutlabi, Ozan Toprakci, Yingfang Yao, Guanjie Xu, Shuli Li, Xiangwu Zhang

Mechanical Engineering Faculty Publications and Presentations

Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanoparticles are synthesized through electrospinning and carbonization processes. The morphology and composition of Ni nanoparticles in carbon nanofibers are controlled by preparing different nanofiber precursors. The lithium-ion battery performance evaluations indicated that the content of electrochemically-inert Ni nanoparticles in carbon nanofibers has a great influence on the final electrochemical performance. For example, at certain Ni contents, these composite nanofibers display excellent electrochemical performance, such as high reversible capacities, good capacity retention, and excellent rate performance, when directly used as binder-free anodes for rechargeable lithium-ion batteries. However, when the Ni content …


A Novel In-House Design Of A Bioreactor For The Modeling Of An In Vitro Blood Brain Barrier Model, Ian Mahaffey Jan 2012

A Novel In-House Design Of A Bioreactor For The Modeling Of An In Vitro Blood Brain Barrier Model, Ian Mahaffey

Biomedical Engineering

The blood brain barrier is the protector of the central nervous system and a physical barrier that functions to regulate the substances that can pass in and out of the brain; it is the function and integrity of this system that keeps the homeostasis of the central nervous system. Yet this shield against foreign invaders in the blood also prevents drugs designed for treatment of various ailments of the central nervous system from reaching their target in the brain. Developing drugs that can pass through this barrier, and understanding it’s function has become an area of increasing interest. Many researchers …


Novel Device To Quantify The Mechanical Properties Of Electrospun Nanofibers, Timothy John Fee Jan 2012

Novel Device To Quantify The Mechanical Properties Of Electrospun Nanofibers, Timothy John Fee

All ETDs from UAB

Electrospun biomaterials are gaining popularity as scaffolding for engineered tissues. These fibrous scaffolds of natural or synthetic polymers can mimic the nano-scale properties of the natural extra-cellular matrix. It is becoming clear that the mechanical deformation of any electrospun matrix plays an important role in cell signaling. However, electrospun biomaterials have inherently complex geometries due to the random deposition of fibers during the electrospinning process. This complex fiber geometry complicates any attempt at quantifying forces exerted on adherent cells during electrospun matrix deformation. In order to quantify the mechanical properties of arrays of individual electrospun fibers in physiological conditions, a …