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2005

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Articles 2581 - 2610 of 3074

Full-Text Articles in Engineering

Damage Mechanics Of Composite Materials Using Fabric Tensors, Ziad N. Taqieddin Jan 2005

Damage Mechanics Of Composite Materials Using Fabric Tensors, Ziad N. Taqieddin

LSU Master's Theses

The major objective of this work is to relate continuum damage mechanics introduced through the concept of fabric tensors to composite materials within the framework of classical elasticity theory. A model of directional data-damage mechanics for composite materials is formulated using fabric tensors. In addition, a general hypothesis for damage mechanics is postulated. It is seen that the two available hypotheses of elastic strain equivalence and elastic energy equivalence may be obtained as special cases of the postulated general hypothesis. This general hypothesis is then used to derive the sought relationship between the damage tensor for composite materials and the …

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Modeling The Fate And Transport Of Chlorinated Benzenes In Baton Rouge Bayou, Sudheer Nimmagadda Jan 2005

Modeling The Fate And Transport Of Chlorinated Benzenes In Baton Rouge Bayou, Sudheer Nimmagadda

LSU Master's Theses

Knowledge of the fate and transport of chlorinated benzenes is necessary at certain sites for effective remediation of contaminated soils using plants. Current research is examining the capability of wetland plants to catalyze degradation or attenuate migration, but again requires knowledge of the uptake of contaminants from an aqueous environment. A two stage model was used to estimate the rate of uptake of contaminants from sediments. The first stage of the model predicts pollutant leaching rates from sediments to the overlying water, which would then be fed into the plant or bioreactor model systems. In this study the flux from …

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The Electrodeposition And Property Study Of Nickel-Rhenium Alloy, Shirong Wen Jan 2005

The Electrodeposition And Property Study Of Nickel-Rhenium Alloy, Shirong Wen

LSU Master's Theses

The electrodeposition of nickel-rhenium alloys from Ni(II) and Re(VII) solution was studies in an aqueous acidic solution. Different plating current density and pH have been carried out, and the effect of them on the composition of the deposited Ni-Re alloy was studied. Wavelength-dispersive spectrometer (WDS) was used to measure the composition of Ni-Re alloy. The thermal stability of nickel-rhenium alloy system has been investigated. Differential scanning calorimetry (DSC) tests have been conducted for the electroplated Ni-Re samples in order to find the possible heating initiated interactions at elevated temperatures. To investigate the thermal stability of Ni-Re alloys, the samples were …

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Assimilation And Removal Of Phosphorus Within The Marshland Upwelling System, Derek A. Evans Jan 2005

Assimilation And Removal Of Phosphorus Within The Marshland Upwelling System, Derek A. Evans

LSU Master's Theses

The marshland upwelling system (MUS) is an alternative onsite wastewater system that was developed to treat domestic wastewater derived from coastal communities. Previous studies have researched the systems ability to treat fecal coliforms and nitrogen. The objectives of this research were to (1) assess the treatment efficiency of the MUS for removing both total phosphorus and orthophosphate, (2) provide preliminary design and operational guidelines for phosphorus removal, and (3) develop a parameter to project longevity of the MUS for treating phosphorus. Performance efficiency was compared for a system which operated for 23 months located in Bayou Segnette State Park and …

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Zeolite And Metal Oxide Catalysts For The Production Of Dimethyl Sulfide And Methanethiol, Craig Plaisance Jan 2005

Zeolite And Metal Oxide Catalysts For The Production Of Dimethyl Sulfide And Methanethiol, Craig Plaisance

LSU Master's Theses

Metal oxide and zeolite catalysts were examined to determine their suitability for the production of methanethiol and dimethyl sulfide from the condensation of methanol and hydrogen sulfide. Fixed bed reactor experiments were used to test the catalysts in these processes. The acid sites of these catalysts were characterized by investigating the thermal desorption of 1-propanamine from these sites. It was found that WO3/ZrO2, La2O3/Al2O3, g-Al2O3, and HZSM-5 catalysts were active and selective in the production of dimethyl sulfide. On these four catalysts, the reaction converting methanol to dimethyl ether and the methanethiol disproportionation reaction were fast and close to equilibrium. …

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A Robust Noise Spectral Estimation Algorithm For Speech Enhancement In Voice Devices, Brett Joseph Chessher Jan 2005

A Robust Noise Spectral Estimation Algorithm For Speech Enhancement In Voice Devices, Brett Joseph Chessher

LSU Master's Theses

In this thesis, a new robust noise spectral estimation algorithm is proposed for the purpose of single-microphone speech enhancement. This algorithm can generate the optimal noise spectral estimates in the Minimum Mean Square Error (MMSE) sense based on the speech statistics in the noisy environments. Compared to the well-adopted conventional noise spectral estimation method using the single-pole recursion, our proposed scheme is more reliable since the recursion coefficients are adaptable and optimal in the MMSE therein. We also propose a new accurate Resulting Signal-to-Noise Ratio (R-SNR) estimator as a quality measure to benchmark the existing noise spectral estimation techniques. This …

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Modeling Destination Choice In Hurricane Evacuation With An Intervening Opportunity Model, Bin Chen Jan 2005

Modeling Destination Choice In Hurricane Evacuation With An Intervening Opportunity Model, Bin Chen

LSU Master's Theses

In this study, a trip distribution model for hurricane evacuation using the intervening opportunity method was developed. Post Hurricane Floyd survey data was used for model calibration and comparison. To model the behavior that people tend to evacuate away from the path of the hurricane, a new concept of equal destination attractiveness was introduced and an extended intervening opportunity model was built on this basis and implemented in TransCAD. The gravity model, intervening opportunity model and its extended version were compared using several statistical measures. This study demonstrates that it is possible to use the intervening opportunity theory to model …

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Mesoscopic Simulation Of Grain Boundary Diffusion Creep In Inhomogeneous Microstructures, Kanishk Rastogi Jan 2005

Mesoscopic Simulation Of Grain Boundary Diffusion Creep In Inhomogeneous Microstructures, Kanishk Rastogi

LSU Master's Theses

At high temperatures, stresses well below the material’s tensile yield strength can induce permanent deformation over a period of time. This time-dependent progressive deformation of a material at constant stress is called Creep and is observed in both crystalline and non-crystalline solids. The principal deformation processes contributing to creep deformation are slip, sub-grain formation and grain-boundary sliding. Mechanisms involving creep of crystalline materials involve either dislocation motion or diffusional flow of atoms or both. Extensive studies have been done to ascertain the creep mechanism in various regimes of temperature and applied stresses. At low stresses and high temperatures, grain boundary …

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Enhanced Gas Recovery Using Pressure And Displacement Management, Thomas Walker Jan 2005

Enhanced Gas Recovery Using Pressure And Displacement Management, Thomas Walker

LSU Master's Theses

The work contained in this thesis combines two previous enhanced gas recovery techniques; coproduction of water and gas from water-drive reservoirs and waterflooding of low pressure gas reservoirs. These two techniques allow the control of reservoir pressure and sweep efficiency through planed production or injection of water. A recovery optimization method, which is applicable to any gas reservoir, was developed using the concept of pressure and displacement management (PDM). Two simulation studies were conducted, using Eclipse©, to investigate recovery optimization by coproduction and waterflooding. From the coproduction study it was determined that the water production rate needed to optimize recovery …

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Pressure-Velocity Correlation Study On 1:50 Scale Model Of The Ttu Wind Engineering Research Field Lab Building, Praveen Kumar Jan 2005

Pressure-Velocity Correlation Study On 1:50 Scale Model Of The Ttu Wind Engineering Research Field Lab Building, Praveen Kumar

LSU Master's Theses

The goal of the present study is to investigate the relationship between incident wind velocity fluctuations and the surface pressure fluctuations on the roof of a low rise building. The goal was fulfilled by studying the pressure velocity correlation on 1:50 scale model of a typical low rise building, the Wind Engineering Research Field Laboratory (WERFL) building located at Texas Tech University, Lubbock. The experimental study was carried out in the LSU Wind Tunnel Laboratory by simulating the boundary layer prevalent at the full-scale site. The velocity profile in the boundary layer was measured using the TSI Hot-Wire system with …

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High-Freequency Cmos Vlsi Chip Testability And On-Chip Interconnect Modeling, Evan Ross Shultz Jan 2005

High-Freequency Cmos Vlsi Chip Testability And On-Chip Interconnect Modeling, Evan Ross Shultz

LSU Master's Theses

As high-speed digital and radio-frequency mixed-signal integrated circuits become increasingly common in product designs in industry, it is important for VLSI designers to be familiar with the challenges of chip testing and the behavior of circuit elements, including on-chip interconnect, at high frequencies. Expensive, specialized test equipment and software simulation packages for high-frequency chip testing and design are not always accessible for student research. This thesis documents the setup and characterization of a best-possible environment for high-frequency chip testing and data acquisition using existing laboratory equipment and resources. Experimental methodologies and measurement results of on-chip interconnect signal integrity and delay, …

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Performance Of Disc Brushless Dc Motor Applied As Gearless Drive For Wheelchair, Deepti Rao Chikkam Jan 2005

Performance Of Disc Brushless Dc Motor Applied As Gearless Drive For Wheelchair, Deepti Rao Chikkam

LSU Master's Theses

The currently used electric drive for a wheelchair consists of brush permanent magnet DC motor and mechanical transmission that drives the wheels. The overall efficiency of this kind of drive usually does not exceed 60%. At present there is under study much more effective drive that consists of brushless DC motor which embedded into the wheel rim directly drives the wheelchair. This type of high efficiency gearless drive is the object of this thesis project. The particular brushless DC motor is a torus - type motor with a high energy rare - earth magnets and ferromagnetic teeth that fill in …

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Power Supply Current [Ips] Based Testing Of Cmos Amplifier Circuit With And Without Floating Gate Input Transistors, Vanikumari Pulendra Jan 2005

Power Supply Current [Ips] Based Testing Of Cmos Amplifier Circuit With And Without Floating Gate Input Transistors, Vanikumari Pulendra

LSU Master's Theses

This work presents a case study, which attempts to improve the fault diagnosis and testability of the power supply current based testing methodology applied to a typical two-stage CMOS operational amplifier and is extended to operational amplifier with floating gate input transistors*. The proposed test method takes the advantage of good fault coverage through the use of a simple power supply current measurement based test technique, which only needs an ac input stimulus at the input and no additional circuitry. The faults simulating possible manufacturing defects have been introduced using the fault injection transistors. In the present work, variations of …

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Graphical Pilot Interface Simulator (Gpis), Jeffry Jorge Handal Jan 2005

Graphical Pilot Interface Simulator (Gpis), Jeffry Jorge Handal

LSU Master's Theses

The thesis develops a graphic interface for a dynamic system simulation implemented in the SIMULINK environment. The dynamic system is a B747-200 modeled as a rigid body with six degrees of freedom. The equations and database of aerodynamic coefficients over the complete flight envelope were provided by NASA’s Langley Research Center for the research project “Aircraft Safety: Managing Control Upsets.” The purpose of the interface is to allow the user to “fly the plane from the keyboard;” i.e., interact with the simulation by manipulating, from the keyboard, the main control surfaces and engine thrust and observing the performance of the …

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Analysis Of Performance Of Single-Phase Reluctance Linear Motor, Subhadra Devi Ganti Jan 2005

Analysis Of Performance Of Single-Phase Reluctance Linear Motor, Subhadra Devi Ganti

LSU Master's Theses

The design and principle of operation, as well as the electromechanical phenomena of a single-phase linear reluctance motor are discussed. The motor with transverse magnetic flux consists of a primary part, which is moving and a secondary part which is stationary and does not have any windings. The motor can operate under AC or DC supply. When supplied from an AC source it must be equipped with a capacitor connected in series with the coil. In this case the motor operates on the basis of resonance in an RLC primary circuit. When supplied from a DC source it must be …

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Modeling Destination Choice And Measuring The Transferability Of Hurricane Evacuation Patterns, Naveen Kumar Modali Jan 2005

Modeling Destination Choice And Measuring The Transferability Of Hurricane Evacuation Patterns, Naveen Kumar Modali

LSU Master's Theses

In this study a gravity model was used to model destination choice during a hurricane evacuation. Hurricane Floyd data was used to calibrate and apply the gravity model. Two different models were generated for different destination types; home of friends/relative and hotels and motels are the two different destination types for which the models were generated. The performance of the gravity model was tested by comparing the observed and estimated OD matrices using the chi-squared test. The results have indicated that gravity model developed in this study can successfully reproduce the observed trip destinations during a hurricane evacuation The Floyd …

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Physical Model Experiments Of The Gas-Assisted Gravity Drainage Process, Amit P. Sharma Jan 2005

Physical Model Experiments Of The Gas-Assisted Gravity Drainage Process, Amit P. Sharma

LSU Master's Theses

The displacement of oil by gas injection in oil reservoirs is an attractive method of improved oil recovery. Commercial gravity-stable gas injection projects have demonstrated excellent recoveries; however, their application has been limited to dipping reservoirs and pinnacle reefs. Horizontal gas floods and the water alternating gas (WAG) processes, practiced in horizontal type reservoirs, have yielded less than satisfactory recoveries of 5-10%. The Gas Assisted Gravity Drainage (GAGD) Process being developed at LSU extends the concept of gravity-stable gas floods to horizontal type reservoirs to improve volumetric sweep and oil recovery. This experimental study consists of a series of visual …

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Superposition Coding Based Co-Operative Diversity Schemes, Anil Kumar Goparaju Jan 2005

Superposition Coding Based Co-Operative Diversity Schemes, Anil Kumar Goparaju

LSU Master's Theses

With a prefixed decoding order at receiver end, superposition coding approach intended for degraded broadcast channels was proposed to improve the average throughput in a point-to-point wireless channel. In this thesis, we first rigorously show the optimal decoding strategy when two Gaussian codebooks are superposed together to send source information to its receiver. Our results rigorously prove the optimality of performing successive interference cancellation at receiver end. Decoding failure at relays imposes a bottle neck to improving overall throughput in relay channels with decode-and-forward relaying strategy. We then extend this framework for a single link to relay channels to optimize …

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Analysis Of Alternative Well Control Methods For Dual Density Deepwater Drilling, Mikolaj Stanislawek Jan 2005

Analysis Of Alternative Well Control Methods For Dual Density Deepwater Drilling, Mikolaj Stanislawek

LSU Master's Theses

The recent push into deepwater is currently limited by high drilling costs resulting from conventional well designs. As a result, dual gradient drilling methods have been proposed. This research investigates riser gas-lift as a potential means to implement a dual gradient system. A primary concern is well control in a system containing so many different density fluids and different flow paths. The specific concerns addressed in this study were kick detection, cessation of formation feed-in, removal of kick fluids, and re-establishing hydrostatic control with a constant bottom hole pressure method. These concerns were studied using a transient, multiphase simulator whose …

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Intrinsic Stress And High Temperature Properties Of Metal-Contanining Hydrogenated Amorphous Carbon Coatings, Bo Shi Jan 2005

Intrinsic Stress And High Temperature Properties Of Metal-Contanining Hydrogenated Amorphous Carbon Coatings, Bo Shi

LSU Doctoral Dissertations

A detailed examination of the intrinsic stress development and mechanical properties of titanium-containing hydrogenated amorphous carbon (Ti-C:H) and W-C:H coatings, deposited in an inductively coupled plasma (ICP) assisted hybrid chemical/physical vapor deposition (CVD/PVD) environment was carried out. Intrinsic stresses within those coatings were found to be compressive and dependent on compositions. The intrinsic compression within Ti-C:H was further shown to be significantly influenced by the energy of ionic species bombarding the substrate during growth. The results suggested that ion bombardment played a significant role in intrinsic stress generation within Ti-C:H, and was likely to influence stress development in other low …

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The Katysat Project: Kids Aren’T Too Young (For Satellites), Benjamin Yuan Jan 2005

The Katysat Project: Kids Aren’T Too Young (For Satellites), Benjamin Yuan

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Benjamin Yuan titled "The KatySat Project: Kids Aren’t Too Young (for satellites)" from April 14, 2005.

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Test 1857: Mccormick Mtx 135 Diesel, Nebraska Tractor Test Lab Jan 2005

Test 1857: Mccormick Mtx 135 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

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Modulation Of Millimeter Waves By Acoustically Controlled Hexagonal Ferrite Resonator, Marina Koledintseva, Alexander A. Kitaytsev Jan 2005

Modulation Of Millimeter Waves By Acoustically Controlled Hexagonal Ferrite Resonator, Marina Koledintseva, Alexander A. Kitaytsev

Electrical and Computer Engineering Faculty Research & Creative Works

To develop millimeter-wave modulators, high-anisotropy uniaxial monocrystalline hexagonal ferrite resonators (HFRs) can be used. One of the ways to modulate the hexagonal ferrite resonator's resonance frequency is to periodically vary the angle between the equilibrium magnetic moment and the external magnetization field. This angular control can be exercised by the mechanical (acoustic) oscillations excited in a piezoelectric slab having a good acoustic contact with the HFR. We consider a quasi-static mathematical model of the uniaxial HFR with the angular control of its resonance frequency. We analyze the amplitudes of harmonics of the modulated millimeter-wave signal, and we derive the optimal …

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Experimental Design And Analysis Of Piezoelectric Synthetic Jets In Quiescent Air, Poorna Mane Jan 2005

Experimental Design And Analysis Of Piezoelectric Synthetic Jets In Quiescent Air, Poorna Mane

Theses and Dissertations

Flow control can lead to saving millions of dollars in fuel costs each year by making an aircraft more efficient. Synthetic jets, a device for active flow control, operate by introducing small amounts of energy locally to achieve non-local changes in the flow field with large performance gains. These devices consist of a cavity with an oscillating diaphragm that divides it, into active and passive sides. The active side has a small opening where a jet is formed, whereas and the passive side does not directly participate in the fluidic jet.Research has shown that the synthetic jet behavior is dependent …

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The Effects Of Parkinson's On Fixational Stability, Erin L. Mallahan Jan 2005

The Effects Of Parkinson's On Fixational Stability, Erin L. Mallahan

Theses and Dissertations

Parkinson's disease (PD) is a progressive, neurological movement disorder. The stability of eye movements in PD is not well understood but many patients report difficulty doing tasks that require stabilized fixation and gaze. The ability to stabilize an image on the retina is critical is acquiring visual information. The purpose of this study was to compare the stability of fixational eye movements of PD patients to those of age-matched controls. Eye movements during simple fixation tasks were recorded from 66 subjects (ages 52 to 84), and 36 age-matched controls (ages 58-85). The absolute velocity of the fixational eye movements were …

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The Use Of Computerized Dynamic Posturography To Assess The Balance In Individuals With Parkinson's Disease, Theresa Erin Mcguirk Jan 2005

The Use Of Computerized Dynamic Posturography To Assess The Balance In Individuals With Parkinson's Disease, Theresa Erin Mcguirk

Theses and Dissertations

Postural instability is one of the hallmarks of Parkinson's disease (PD), currently evaluated using several subjective tools. However, the nature and degree of the resulting balance deficit is not well specified by these tools. Computerized dynamic posturography (CDP) provides an objective assessment by isolating and quantifying sensory and motor contributions to balance control. The purpose of this study was to compare balance in individuals with PD to a control group using CDP (NeuroCom Smart Balance Master® system). Testing took place at the Southeast Parkinson's disease Research Education and Clinical Center (PADRECC), an interdisciplinary center of excellence for people with PD …

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Iterative Methods For The Reconstruction Of Tomographic Images With Unconventional Source-Detector Configurations, Abey Mukkananchery Jan 2005

Iterative Methods For The Reconstruction Of Tomographic Images With Unconventional Source-Detector Configurations, Abey Mukkananchery

Theses and Dissertations

X-ray computed tomography (CT) holds a critical role in current medical practice for the evaluation of patients, particularly in the emergency department and intensive care units. Expensive high resolution stationary scanners are available in radiology departments of most hospitals. In many situations however, a small, inexpensive, portable CT unit would be of significant value. Several mobile or miniature CT scanners are available, but none of these systems have the range, flexibility or overall physical characteristics of a truly portable device. The main challenge is the design of a geometry that optimally trades image quality for system size. The goal of …

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Numerical Modeling Of Synthetic Jets In Quiescent Air With Moving Boundary Conditions, Nicholas D. Castro Jan 2005

Numerical Modeling Of Synthetic Jets In Quiescent Air With Moving Boundary Conditions, Nicholas D. Castro

Theses and Dissertations

Flow control is a key factor in optimizing the performance of any vehicle moving through fluids. Particularly, in aerodynamics there are many potential benefits for implementing synthetic jets to achieve aircraft designs with less moving parts, uper- maneuverability, and separation control for fuel economy. Piezoelectric synthetic jets are of special interest because of their lightweight and low power consumption. Numerous publications on such jets are available. Actuator properties and boundary conditions relevant to this particular application however are often overlooked. The focus of this project is to numerically model synthetic jets in quiescent air to study the influence of cavity …

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Design, Fabrication And Performance Evaluation Of An Impedimetric Urea Biosensor System, Vandana Gupta Jan 2005

Design, Fabrication And Performance Evaluation Of An Impedimetric Urea Biosensor System, Vandana Gupta

Theses and Dissertations

An impedance bioanalyzer system comprising an in-vitro biotransducer, instrumentation and control software for the measurement of urea, potentially in blood dialysate, has been developed. The biotransducer comprises of a microlithographically fabricated interdigitated microsensor electrode (IME) onto which was cast a biorecognition layer conferred with the specificity of the enzyme urease. Urease hydrolysis of urea produces NH4+, HC03- and OH- ions that decrease the device's impedance. The temporal rate of change (kinetic) and the extent of change (equilibrium) of ion concentration were measured as the sensor's response. Five formats: [i) unPEGylated urease-containing poly(hydroxyethylmethacrylate) [p(HEMA)] hydrogel, ii) PEGylated urease-containing p(HEMA) hydrogel, iii) …

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The Extraction Of Type Ii Collagen And The Electrospinning Of Nano-Fibrous Scaffolds, Danielle Careen Knapp Jan 2005

The Extraction Of Type Ii Collagen And The Electrospinning Of Nano-Fibrous Scaffolds, Danielle Careen Knapp

Theses and Dissertations

Articular cartilage lining joints, such as in the knee, functions to reduce friction and absorb shock. Collagen type II is the largest constituent in the extracellular matrix of articular cartilage and its restoration is of the highest interest to tissue engineers. Cartilage has little ability to naturally regenerate due to the absence of vascularity and the inability of the chondrocytes to proliferate at a high rate. It would be ideal to create a mimicking extracellular matrix/scaffold from type II collagen that could possibly be used to replace damaged articular cartilage that has the same function and morphology. Three different groups …

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