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Articles 1501 - 1530 of 2820

Full-Text Articles in Engineering

Numerical Investigation Of Cryopreserved Zebrafish Sperm Cell Activation In Microchannels, Thomas Foster Scherr Jan 2014

Numerical Investigation Of Cryopreserved Zebrafish Sperm Cell Activation In Microchannels, Thomas Foster Scherr

LSU Doctoral Dissertations

This aim of this research project is to probe the activation process of zebrafish spermatozoa. Zebrafish are a model species for biological engineering applications, and the cryopreservation of their reproductive cells allows for inexpensive cataloging and maintenance of valuable biological material. Evaluation of cryopreservation protocols for aquatic sperm cells is typically accomplished by motility analysis after subjecting cells to a cryopreservation treatment. In zebrafish sperm cells, motility is initiated when cells come into contact with a hypo-osmotic environment. Subsequent activation analysis is currently done manually and brings with it an inherent difficulty and error. This process is slow and not …


Evaluation Of Triploid Oysters As A Tool To Assess Short- And Long-Term Seafood Contamination Of Oil Spill-Impacted Areas, Martin Scott Miles Jan 2014

Evaluation Of Triploid Oysters As A Tool To Assess Short- And Long-Term Seafood Contamination Of Oil Spill-Impacted Areas, Martin Scott Miles

LSU Doctoral Dissertations

Many of the organic components of oil have the capacity to persist in the environment, bioaccumulate in tissues, and are toxic to surrounding organisms. Since the early 1970s, environmental assessment programs have utilized bivalves as monitoring tools of chemical contaminants in the marine environment. Because of their sedentary and filter-feeding habit (bioaccumulation), mussels and oysters been employed as sentinel organisms in environmental quality monitoring studies in coastal ecosystems. The use of indigenous (diploid) bivalves for biomonitoring water quality is limited during the summer months due to high stress and changes in biochemical composition induced by reproductive development. In this work …


Investigating Different Coding Environments For Simplified Reservoir Characterization Models, Atheer Mohammad Al Attar Jan 2014

Investigating Different Coding Environments For Simplified Reservoir Characterization Models, Atheer Mohammad Al Attar

LSU Master's Theses

Reservoir characterization is one of the most important tasks that determines the recovery plan for a specific reservoir. This process incorporates a significant amount of data acquisition and processing to finally develop an acceptable model that matches the production history and can forecast the future production behavior. The model also should be able to adapt to changes along the way: adding or removing producers or injectors, changing the injection pattern, recompletions and converting wells are all examples of possible changes that are common in the oil and gas industry. Usually these changes are modeled by running field-scale simulations and providing …


Restraint Moments Due To Thermal Gradients In Continuous Prestressed Concrete Girder Bridges, Sushovan Ghimire Jan 2014

Restraint Moments Due To Thermal Gradients In Continuous Prestressed Concrete Girder Bridges, Sushovan Ghimire

LSU Master's Theses

This research is motivated by the need to develop new bridges, using new materials and construction details to achieve the goal of building longer span bridges that are safe and durable. The study of precast/prestressed concrete bridges made continuous started early in the 1960’s. Continuous bridges have many advantages compared to simple span bridges such as reduction in structural depth, riding comfort and reserve load capacity under overload conditions. They also eliminate joints that require a lot of maintenance and cause deterioration in some cases. The design and construction of continuous bridges requires the consideration of many factors that are …


Determining The Location Of Congestion Hot Spots In Urban Areas Using Image Analysis, Aditya Mokkapati Jan 2014

Determining The Location Of Congestion Hot Spots In Urban Areas Using Image Analysis, Aditya Mokkapati

LSU Master's Theses

The identification of congestion hot spots plays an important role in congestion monitoring of highway and arterial systems. Traditionally, vehicle detection systems or probe vehicles are used to measure travel time and identify congestion hot spots. This approach is time-consuming and resource intensive. With the advent of new technologies like crowdsourcing, travel time can be collected more cost-effectively using fewer resources. The research presented in this paper develops a new methodology to identify congestion hot spots in an urban area using freely available historical speed data gathered by Google and published as a traffic layer in Google maps. The methodology …


Continuous Reservoir Modeling Updating By Integrating Experimental Data Using An Ensemble Kalman Filter, Ting Sun Jan 2014

Continuous Reservoir Modeling Updating By Integrating Experimental Data Using An Ensemble Kalman Filter, Ting Sun

LSU Doctoral Dissertations

The continuous researvoir model updating is widely used to calibrate reservoir simulation models to production data, but many challenges remain. First, few real field data are available to test the new history matching method, and most of the data sets are synthetic cases. Second, computational cost may be high when using non-Gaussian priors or nonlinear models. Third, with large complex models, the simulation runs and history matching method require huge memory allocations. This dissertation achieves a continuous reservoir model updating workflow with a meter-scale , two-phase flow experiment. Both production and seismic data are collected in the experiment. Because the …


Hot Corrosion Behaviour Of New Candidates For Thermal Barrier Coatings Application In Turbine Simulated Environments, Mohammad Hamed Habibi Jan 2014

Hot Corrosion Behaviour Of New Candidates For Thermal Barrier Coatings Application In Turbine Simulated Environments, Mohammad Hamed Habibi

LSU Doctoral Dissertations

Thermal barrier coatings (TBCs) are used gas turbine engines. The current material of choice (YSZ) degrades when it contacts with impurities arise from low quality fuels such vanadium and sulfur. YSZ cannot be used in temperature higher than 900˚C. Higher efficiency and performance of gas turbine engines will require a new generation of thermal barrier coatings (TBCs). In current work, hot corrosion behavior of new candidates including Gd2Zr2O7, ZrO2 stabilized with Ta2O5, zirconia stabilized with both Ta2O5 and Y2O3 and zirconia stabilized with CeO2 and TiO2 is investigated. For YSZ case, the reaction between NaVO3 and Y2O3 produces YVO4 and …


Catalytic Active Site, Mechanistic And Kinetic Studies Of Dry (Co2) Reforming Of Methane Over Lanthanum Zirconate (La2zr2o7) Pyrochlores, Devendra Pakhare Jan 2014

Catalytic Active Site, Mechanistic And Kinetic Studies Of Dry (Co2) Reforming Of Methane Over Lanthanum Zirconate (La2zr2o7) Pyrochlores, Devendra Pakhare

LSU Doctoral Dissertations

Dry (CO2) reforming of CH4 (DRM) produces commercially important synthesis gas (H2 and CO) with H2/CO ≤ 1, which can be used for synthesis of higher alkanes and oxygenates. DRM is highly endothermic and requires temperatures as high as 800°C-1000°C to attain high equilibrium conversions. A major problem associated with DRM is catalyst deactivation due to carbon deposition. Thus it is imperative that the catalyst used for DRM must resist deactivation due to sintering and carbon deposition. DRM is well studied in the literature over various catalysts, however, there is no literature, except the Ashcroft (1993) article, for DRM over …


Crack Self-Healing In Sic/Spinel Nanocomposite, Fariborz Tavangarian Jan 2014

Crack Self-Healing In Sic/Spinel Nanocomposite, Fariborz Tavangarian

LSU Doctoral Dissertations

Spinel is one of the best known and widely used ceramic materials. It has good thermal shock resistance, high chemical inertness in both acidic and basic environments, excellent optical and dielectric properties, high strength at both elevated and normal temperatures, and has no phase transition up to the melting temperature (2135°C). Spinel is used in the metallurgical, electrochemical, and chemical industrial fields. It has also found some applications in dentistry, catalyst supports, humidity sensors, reinforcing fibers, photoluminescent materials, etc. One of the limitations of spinel ceramic is its brittleness. Furthermore, at high temperature applications, a rapid heating or cooling can …


Polycyclic Aromatic Hydrocarbon Degradation In Tidally Influenced Coastal Marsh Wetland Studied In Laboratory Mesocosm, Doorce S. Batubara Jan 2014

Polycyclic Aromatic Hydrocarbon Degradation In Tidally Influenced Coastal Marsh Wetland Studied In Laboratory Mesocosm, Doorce S. Batubara

LSU Doctoral Dissertations

The compact mesocosm which was designed for a laboratory scale was used for the kinetic study of refractory organic compounds in a tidally influenced coastal marsh wetland soil. The tidal cycles were controlled pneumatically using an air chamber inside the mesocosm tank. Phenanthrene as the test compound showed that its degradation in the intertidal wetland soil was faster than that in the subtidal wetland soil. Oxygen resupply during the tidal cycles to the intertidal wetland soil would enhance the degradation. Comparison of degradation rates of phenanthrene (Phe), pyrene (Pyr), and benzo[e]pyrene (BeP) were also studied using the mesocosm. The degradation …


Applications Of The Variational Approach To Fracture Mechanics, Ataollah Mesgarnejad Jan 2014

Applications Of The Variational Approach To Fracture Mechanics, Ataollah Mesgarnejad

LSU Doctoral Dissertations

In this study we present the variational approach to fracture mechanics as a versatile tool for the modeling of the fracture phenomenon in solids. Variational fracture mechanics restates the problem of initiation and propagation of cracks in solids as an energy minimization problem. The edifice of this energy minimization problem is such that unlike other methods (e.g. extended finite element method XFEM, cohesive-zone methods) the variational approach to fracture mechanics, diminishes the need for an a priori knowledge of the crack path or ad hoc assumptions in the form of path selection laws. We will show applications of the variational …


Electrochemical Reduction Of Co2 On Supported Cu2o Catalysts, Joel Niño Galvez Bugayong Jan 2014

Electrochemical Reduction Of Co2 On Supported Cu2o Catalysts, Joel Niño Galvez Bugayong

LSU Doctoral Dissertations

We have examined Cu-based catalyst materials that enable the conversion of CO2 to useful products such as fuels and chemical feedstocks by electrochemical reduction. In particular, we compared the electrocatalytic activity of supported Cu2O particles prepared using electrodeposition and wet chemical methods. The particles had cubic structure, ranging in size from 40 nm to 900 nm and consisting of low index planes. We observed significantly different product distribution on these catalysts compared to polycrystalline Cu, specifically for methane and ethylene formation. While Cu particles showed higher faradaic efficiency for methane formation compared to ethylene formation, we observed that Cu2O particles …


Poroelastic Inhomogeneities: Applications In Reservoir Geomechanics, Houman Bedayat Jan 2014

Poroelastic Inhomogeneities: Applications In Reservoir Geomechanics, Houman Bedayat

LSU Doctoral Dissertations

The scarce amount of conventional hydrocarbon reservoirs and increase of fuel consumption in the world have made production from unconventional hydrocarbon resources inevitable. Because of the low permeability of unconventional formations, fractures are the main paths for the fluid to flow. Therefore, detailed knowledge of the size, orientation, and permeability of the fracture systems are essential for reservoir engineers. Permeability of the fractures is function of their volume and opening, and stress and fluid pore pressure distribution in the formation. Since reservoir pressure may change over the production life of the reservoir, studying stress redistribution and mechanical behavior of the …


New Approaches To Smart Grid Security With Scada Systems, Bixiang Tang Jan 2014

New Approaches To Smart Grid Security With Scada Systems, Bixiang Tang

LSU Doctoral Dissertations

The use of information technology in electric power grid introduces the vulnerability problem looming the future smart grid. The supervisory control and data acquisition (SCADA)is the first defense, which itself is undermined by potential malicious attacks. This dissertation studies two particular security threats facing the smart grid and SCADA systems: the unobservable attack and the replay attack. The former is well known in fault detection of the power grid and has received renewed interest in the past a few years, while the latter is motivated by the Stuxnet worm allegedly used against the nuclear facilities in Iran. For unobservable attacks, …


Novel Syntheses And Surface Modifications Of Electrode Materials For Superior Lithium-Ion Batteries, Jianqing Zhao Jan 2014

Novel Syntheses And Surface Modifications Of Electrode Materials For Superior Lithium-Ion Batteries, Jianqing Zhao

LSU Doctoral Dissertations

Rechargeable lithium-ion battery is one of the most promising energy conversion and storage systems that offers high energy and powder densities, long service life and assuring safety. Performance of lithium-ion batteries crucially relies on electrochemical characteristics of electrode materials, i.e., anode and cathode materials. This dissertation work aims at developing novel electrode materials with high capacity, excellent cycling stability and remarkable rate capability for next-generation lithium-ion batteries. The effects of surface modifications for LiMn2O4 cathode materials are studied by depositing ultrathin conformal amphoteric oxides via atomic layer deposition (ALD). In the case of ZnO coating, the thickness of ZnO ALD …


Advanced Control Of Small-Scale Power Systems With Penetration Of Renewable Energy Sources, Shaghayegh Kazemlou Jan 2014

Advanced Control Of Small-Scale Power Systems With Penetration Of Renewable Energy Sources, Shaghayegh Kazemlou

LSU Doctoral Dissertations

Stability, protection, and operational restrictions are important factors to be taken into account in a proper integration of distributed energy. The objective of this research is presenting advanced controllers for small-scale power systems with penetration of renewable energy sources resources to ensure stable operation after the network disturbances. Power systems with distributed energy resources are modeled and controlled through applying nonlinear control methods to their power electronic interfaces in this research. The stability and control of both ac and dc systems have been studied in a multi-source framework. The dc distribution system is represented as a class of interconnected, nonlinear …


Effect Of Process Mixing On The Size Distribution And Mean Diameter Of The Thiol-Triacrylate Microcapsules, Rubaiyet Abedin Jan 2014

Effect Of Process Mixing On The Size Distribution And Mean Diameter Of The Thiol-Triacrylate Microcapsules, Rubaiyet Abedin

LSU Master's Theses

An important limitation in the development of the microparticles is the difficulty to develop a precise size distribution. Microparticles have a wide spread applicability in different fields including medical, pharmaceutical, textile, cosmetics, pesticide, printing industry, etc. The large and growing impact of microencapsulation in different fields of technology has made this process important. Microparticle size is a primary determinant of control release mechanism and the reaction kinetics and also impacts the allowable routes of administration, The main objective of this research work is to evaluate the effect of the process mixing on the size and size distribution of the trithiol-triacrylate …


An Experimental Investigation Of The Effects Of N-Decane On The Supercritical Pyrolysis Of Toluene, Catherine A. Grubb Jan 2014

An Experimental Investigation Of The Effects Of N-Decane On The Supercritical Pyrolysis Of Toluene, Catherine A. Grubb

LSU Master's Theses

Future and current high-speed jet aircraft will require their fuels to act as the primary coolants as well as propellants. Fuels will be exposed to severe temperatures and pressures in hypersonic aircraft, up to 700°C and 130 atm, respectively, conditions that are supercritical for most pure hydrocarbons. Under supercritical conditions, hydrocarbon fuels undergo pyrolytic reactions, which may lead to the formation of polycyclic aromatic hydrocarbons (PAH), known precursors to carbonaceous solid deposits. Such deposits may clog fuel lines and injection nozzles, hindering safe engine performance. Hence, it is important to understand the reactions that lead to the formation of PAH. …


Assimilation, A Biological Nitrogen Removal Strategy For Freshwater Ornamental Fish Hatcheries, Fatemehsadat Fahandezhsadi Jan 2014

Assimilation, A Biological Nitrogen Removal Strategy For Freshwater Ornamental Fish Hatcheries, Fatemehsadat Fahandezhsadi

LSU Master's Theses

Freshwater ornamental fish production is a major component of aquaculture in the southeastern United States. Closed recirculating aquaculture systems (RASs) allow freshwater ornamental fish hatcheries to mimic native water quality conditions for sensitive species. Total ammonia-N (TAN) removal is the major concern for closed RASs. Biological nitrification is the common method to control TAN. However, the nitrification process might be impaired in acidic water condition with pH<7. Another issue of using the nitrification process for TAN removal is that the nitrification is not sufficient to compensate for the amount of ammonia released in larval production systems because of slow growth rate of nitrifying bacteria. To address these issues, this study suggests an aerobic assimilation strategy in which fast growing heterotrophic bacteria directly convert TAN into microbial biomass. The heterotrophic bacteria needs an external carbon source. This study employed polyhydroxybutyrate (PHB) that is a solid insoluble bioplastic, as a carbon source in the aerobic assimilation process to avoid releasing carbon into the system. In order to understand the applicability of an assimilation process instead of nitrification, this study compared the ammonia-N removal rate by aerobic assimilation biofilters operating @ pH 8 and 6.5 in a batch system. The study also quantified the performance of an aerobic assimilation strategy under different continuous nitrogen loading regimes. This investigation can be used to establish the biofilter air pulsing frequency, which is the optimized air pulsing frequency that avoids clogging in the system. The results showed that there was no apparent release of carbon in the water tank. Unlike nitrification, assimilation strategy for TAN removal was not significantly different in two pH of 8 and 6.5 @ 28 ° C. The average consumption rate of the PHB was found as 21.93± 0.43 grams of PHB consumed per gram of TAN. The results from the continuous system, at a continuous feeding rate of 350 mg-N/d, suggested that the optimum air pulsing frequency through the PHB bed for releasing the excess biosolids was about 6-hour. In general, the study found that the aerobic assimilation using polyhydroxybutyrate (PHB) as a carbon source is an applicable method for ammonia-N removal particularly for freshwater ornamental fish production systems. The drawback against this approach is that the PHB beads are expensive. However, our investigations show that the average cost of the PHB beads have been decreased dramatically during the last few years. This might indicate that the assimilation using PHB beads can be a reasonable choice for ammonia-N removal particularly for freshwater ornamental fish production systems.


Using Eye-Tracking To Investigate Strategy And Performance Of Expert And Novice Control Room Operators, Christina Marie Koffskey Jan 2014

Using Eye-Tracking To Investigate Strategy And Performance Of Expert And Novice Control Room Operators, Christina Marie Koffskey

LSU Master's Theses

There is lacking research within the Petrochemical Industry that uses eye-tracking to explore the differences between the strategies of expert and novice control room operators as they monitor and address process parameters that could be used to improve novice training programs and interface design. Scan paths and three eye-tracking metrics (Fixation Frequency, Gaze Duration Mean, and Gaze Percentage) were used to investigate the differences in eye behavior of three expert control room operators and six novice students as they monitored and corrected a Crude Refinement simulation. A 2x2x2 mixed factor design was used to explore the effects that expertise (expert …


Low Frequency Improvements To Commercial Geophones, Brian Michael Holden Jan 2014

Low Frequency Improvements To Commercial Geophones, Brian Michael Holden

LSU Master's Theses

Commercial geophones have been used in the field of geology for many years. They are commonly used to detect oil and gas deposits and create three dimensional simulations of the earth. Geophones are commonly made up of a spring mounted magnetic mass moving back and forth in a wire coil to create a voltage. The response of the coil is proportional to the velocity of the ground. At various frequencies, seismic events can be measured using a geophone. However, most commercial geophones only allow accurate measurements of frequencies down to approximately five hertz. By using a feedback circuit, an attempt …


Analysis Of Microseismic Events Associated With Hydraulic Fracture Propagation, Chennu Fan Jan 2014

Analysis Of Microseismic Events Associated With Hydraulic Fracture Propagation, Chennu Fan

LSU Master's Theses

Previous practice to determine the source mechanism of microseismic events associated with hydraulic fracture typically includes only far-field terms in moment tensor inversion. The intermediate-field terms and near-field term are normally ignored because of increased complexity in the calculation. Source-receiver distances in hydraulic fracturing are usually 1000 ft and the effects of near and intermediate-field terms are still unknown. We perform a study to improve the precision of the source mechanism by including the intermediate-field term in moment tensor inversion. We find that the intermediate-field term contributes 1/3 of the signal amplitude when the source-receiver distance is 1000 ft. The …


Rare Earth/Transition Metal Oxides For Syngas Cleanup, Rui Li Jan 2014

Rare Earth/Transition Metal Oxides For Syngas Cleanup, Rui Li

LSU Doctoral Dissertations

Syngas from gasification of biomass or biomass and coal is a potential source of renewable energy. However, byproducts such as H2S and tars must be removed before further utilization or processing of syngas. Rare earth oxides (REOs, e.g., Ce/LaOx (1.7< x <2)) mixed with transition metals (e.g., Mn, Fe) were synthesized by various methods, and in some cases supported on a thermally stable alumina. Both desulfurization and tar reforming experiments were conducted at high temperatures under similar conditions with synthetic effluents in order to achieve better heat integration and higher yield to desired products CO and H2. The sulfur capacities at temperatures from 900-1025 K with air regeneration were measured for repeat cycles until a stable, reversible capacity was obtained. The oxidized and sulfided (reduced) sorbents were characterized by XRD, XANES, XAFS, TPR and BET. Density functional theory calculations were used to aid in interpreting characterization data and in explaining the enhanced S adsorption capacities. The results showed that mixed REOs, such as Ce/Tb, and Ce/La synthesized by a templated sol-gel approach do not have high sulfur capacities. The presence of either CO2 or H2O inhibits the adsorption of H2S. However, addition of Mn to REOs effectively increased the sulfur capacity, and Mn-REO sorbents are regenerable even in the presence of air, although there is some sulfate formation. The formation of elemental sulfur during regeneration could be related to the oxygen vacancies promoted by doping Mn into the ceria lattice. DFT calculations suggested doping Mn into CeO2 decreased the vacancy formation energies and lowered the H2S adsorption energy. In contrast, for MnO-doped REOs supported on ã-Al2O3, although their surface areas remained high after multi-cycle usage, the probable formation of MnAl2O4 as observed by XANES reduces the sulfur capacities. Reforming experiments were carried out using synthetic syngas mixtures with C10H8 as a tar model compound, both with and without H2S. The results showed that CO2 and H2O inhibit the reforming activities to some extent. Fe- or Mn-doped supported REOs are promising tar cleanup catalysts. They exhibited higher sulfur tolerance, less coking, and less methanation than typical Ni-based high temperature reforming catalysts. This behavior is in part attributed to enhanced generation of oxygen vacancies in the doped REOs.


A Virtual Testbed For Embedded Systems, Shrikant Labade Jan 2014

A Virtual Testbed For Embedded Systems, Shrikant Labade

LSU Master's Theses

Hardware-In-the-Loop (HIL) Simulation is a simulation approach in which a hardware embedded processor is connected to the simulation computer that simulates the electrical/mechanical devices controlled by the embedded processor. By using a real-time simulation computer and special-purpose hardware for connecting to the embedded processor, this method of simulation can be very precise but is costly. We are proposing an alternative method, HIL simulation with a network link, in which the device under test (the embedded processor) communicates with the simulation computer over a network connection (in our case a serial line) instead of through special-purpose hardware. We present an abstraction …


Association Of Lean Implementation On Perceived Organizational Maturity Levels Of Managers And Staff In The Public Sector, Patrick Eduardo O'Mara Jan 2014

Association Of Lean Implementation On Perceived Organizational Maturity Levels Of Managers And Staff In The Public Sector, Patrick Eduardo O'Mara

LSU Master's Theses

Extensive research has shown the impact of Lean implementation at the process level of an organization to increase quality, reduce cycle time, and reduce operational costs. However, little research has been done to associate Lean with improvement at the strategic level of an organization. The objectives of the present research were to (a) study the association of Lean implementation with maturity levels of employees (b) study the relationship between Lean implementation in the levels of agreement with cohesion between managers and staff in evaluating perceived current state and desired state of organizational practices (c) identify potential barriers of Lean implementation …


A Study Of Induction Pyrolysis Of Lignicellulosic Biomass For The Production Of Bio-Oil, Charles Edward Henkel Jan 2014

A Study Of Induction Pyrolysis Of Lignicellulosic Biomass For The Production Of Bio-Oil, Charles Edward Henkel

LSU Master's Theses

The increasing demand for energy coupled with a growing concern that the combustion of fossil fuels has on the environment, through the production of greenhouse gases, has created a demand for renewable energy sources. The demand for renewable energy, particularly liquid transportation fuels, can be met in part by the use of biomass based liquid fuels. There are several methods that can be used to produce biomass based fuels, but only thermochemical conversion (pyrolysis) can readily convert lignocellulosic biomass into a fuel-like liquid, bio-oil. The pyrolytic conditions for obtaining maximum liquid yields vary, but many of the criteria can be …


Silver Nanoparticle Oligonucleotide Conjugate For Targeted Gene Silencing, Alyson Nanette Moll Jan 2014

Silver Nanoparticle Oligonucleotide Conjugate For Targeted Gene Silencing, Alyson Nanette Moll

LSU Master's Theses

This project explored a gene-regulated chemotherapy using a silver nanoparticle (SNP) conjugated with deoxyribozyme (DNAzyme) oligonucleotides which target a mutated gene in select cancer cells, sensitize them to doxorubicin treatment. Light exposure to the SNP-DNAzyme conjugates disengages the oligonucleotides and permits specific cleavage of the Kirsten Rat Sarcomal Oncogene Homolog (K-RAS) mRNA. These conjugates could provide spatiotemporal specificity in killing only those photoexposed cells with the mutant gene. Synthesis, functionalization and characterization of citrate and hydroxypropyl cellulose SNP conjugates confirmed attachment and photolytic release of the thiol-modified 10-23 DNAzyme. Gel electrophoresis was used to demonstrate DNAzyme photoactivation, showing greater K-RAS …


Novel Nanostructured Titania And Titania Nanocomposites For Photovoltaics And Photocatalysis, Xinning Luan Jan 2014

Novel Nanostructured Titania And Titania Nanocomposites For Photovoltaics And Photocatalysis, Xinning Luan

LSU Doctoral Dissertations

With the consumption of energy continually increasing around the world and the main source of this energy, fossil fuels, slowly being depleted, the need for alternate sources of energy is becoming more and more pertinent. Demand for solar energy has experienced exponential increase over the last decade. Nanostructured TiO2 has attracted significant attention due to its nontoxicity, low cost and wide applications in photovoltaics and photocatalysis. This research is focused on novel synthesis and surface modification of TiO2 nanotube arrays for applications in advanced dye-sensitized solar cells (DSSCs) and efficient photocatalysis. The first part of this work entails fast synthesis …


Energy And Thermodynamically Based Approaches For Analysis Of Damage In Contact Problems, Afshin Babaie Aghdam Jan 2014

Energy And Thermodynamically Based Approaches For Analysis Of Damage In Contact Problems, Afshin Babaie Aghdam

LSU Doctoral Dissertations

A novel methodology for analysis of damage in contact problems in presented. Two important categories of contact damage are studied, namely crack nucleation and adhesive wear. The proposed methodology is primarily based on the laws of energy and thermodynamics, and as such offers great advantages by unifying the analysis of damage in a variety of contact configurations. Crack nucleation is the first damage type analyzed. For this purpose, the line-contact fretting configuration is chosen. A thermodynamically-based continuum damage mechanics (CDM) approach is employed. Intense stress gradients in the contact region are found to be highly influential in the crack nucleation …


Spectrum Sensing, Spectrum Monitoring, And Security In Cognitive Radios, Erfan Soltanmohammadi Jan 2014

Spectrum Sensing, Spectrum Monitoring, And Security In Cognitive Radios, Erfan Soltanmohammadi

LSU Doctoral Dissertations

Spectrum sensing is a key function of cognitive radios and is used to determine whether a primary user is present in the channel or not. In this dissertation, we formulate and solve the generalized likelihood ratio test (GLRT) for spectrum sensing when both primary user transmitter and the secondary user receiver are equipped with multiple antennas. We do not assume any prior information about the channel statistics or the primary user’s signal structure. Two cases are considered when the secondary user is aware of the energy of the noise and when it is not. The final test statistics derived from …