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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

A Study On The Catalytic Pyrolysis And Combustion Characteristics Of Turkish Lignite And Co-processing Effects With Biomass Under Various Ambient Conditions

Ehsan, Abbasi Atibeh 01 August 2012 (has links) (PDF)
In this study the catalytic pyrolysis and combustion characteristics of Turkish coal samples in O2/N2 and O2/CO2 (oxy-fuel conditions) ambient conditions were explored and the evolution of emissions during these tests was investigated using non-isothermal Thermo-gravimetric Analysis (TGA) technique combined with Fourier Transform Infrared (FTIR) spectroscopy. Potassium carbonate (K2CO3), calcium hydroxide (Ca(OH)2), iron (III) oxide (Fe2O3) and iron (III) chloride (FeCl3) were employed as precursors of catalysts to investigate the effects of potassium (K), calcium (Ca) and iron (Fe). Furthermore the effects of these catalysts on calorimetric tests of Turkish coal samples were investigated. TGA-FTIR pyrolysis tests were carried out in 100 % N2 and 100 % CO2 ambient conditions which are the main diluting gases in air and oxy-fuel conditions. Lignite pyrolysis tests revealed that the major difference between pyrolysis in these two ambient conditions was observed beyond 720
322

Macromolecular Characterization Of Adipose Tissues In Inbred Obese Mouse Models

Sen, Ilke 01 August 2012 (has links) (PDF)
Obesity is a metabolic disorder that results in elevated levels of free fatty acids and triglycerides in the blood circulation, which further leads to accumulation of lipids within various tissues. Like in other similar metabolic disorders, obesity is thought to be originated from structural and regulatory changes in macromolecular assemblies. This current study aims to investigate the effects of obesity on macromolecular alterations in order to characterize Berlin fat mouse inbred (BFMI) lines which arenew models for the obesity research that may contribute to understanding of spontaneous obesity without induction of a high fat diet. Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to characterize content and structure of macromolecules in male and female control (DBA/2J) and BFMI lines / namely BFMI856, BFMI860 and BFMI861, in two different adipose tissues / inguinal fat (IF) which is subcutaneous adipose tissue (SAT), gonadal fat (GF) which is visceral adipose tissue (VAT). Structural and compositional alterations in proteins, lipids, saturated and unsaturated lipid contents, nucleic acid, collagen and glycogen contents and variations in the lipid chain length were determined. BFMI860 and BFMI861 lines were found to be the most affected lines since they showed the indications of lipid peroxidation and insulin resistance more severely as they had lower glycogen content in all tissues and lower unsaturated lipid content especially in IF adipose tissues. Moreover, structural changes in lipids were observed especially in male GF adipose tissues of BFMI856 and BFMI861 lines. Protein content decreased significantly specifically in female IF adipose tissues but no change was observed in the structure. Furthermore, BFMI852 line was found to be affected different than other lines and had an effect on especially female IF. To conclude, obesity induced changes differ in BFMI lines according to the gender, adipose tissue type and distinctness in the strains.
323

An experimental investigation of the urea-water decomposition and selective catalytic reduction (SCR) of nitric oxides with urea using V2O5-WO3-TiO2 catalyst.

Johar, Jasmeet Singh 01 November 2005 (has links)
Two flow reactor studies, using an electrically heated laminar flow reactor over Vanadia based (V2O5-WO3/TiO2) honeycomb catalyst, were performed at 1 atm pressure and various temperatures. The experiments were conducted using simulated exhaust gas compositions for different exhaust gases. A quartz tube was used in order to establish inert conditions inside the reactor. The experiments utilized a Fourier transform infrared (FTIR) spectrometer in order to perform both qualitative and quantitative analysis of the reaction products. Urea-water solution decomposition was investigated over V2O5-WO3/TiO2 catalyst over the entire SCR temperature range using the temperature controlled flow reactor. The solution was preheated and then injected into pure nitrogen (N2) stream. The decomposition experiments were conducted with a number of oxygen (O2) compositions (0, 1, 10, and 15%) over the temperature range of 227oC to 477oC. The study showed ammonia (NH3), carbon-dioxide (CO2) and nitric oxide (NO) as the major products of decomposition along with other products such as nitrous oxide (N2O) and nitrogen dioxide (NO2). The selective catalytic reduction (SCR) of nitric oxide (NO) with urea-water solution over V2O5-WO3/TiO2 catalyst using a laboratory laminar-flow reactor was investigated. Urea-water solution was injected at a temperature higher than the vaporization temperature of water and the flow reactor temperature was varied from 127oC to 477oC. A FTIR spectrometer was used to determine the concentrations of the product species. The major products of SCR reduction were NH3, NO and CO2 along with the presence of other minor products NO2 and N2O. NO removal of up to 87% was observed. The aim of the urea-water decomposition experiments was to study the decomposition process as close to the SCR configuration as possible. The aim of the SCR experiments was to delineate the effect of various parameters including reaction temperature and O2 concentration on the reduction process. The SCR investigation showed that changing parameter values significantly affected the NO removal, the residual NH3 concentration, the temperature of the maximum NO reduction, and the temperature of complete NH3 conversion. In the presence of O2, the reaction temperature for maximum NO reduction was 377?C for ratio of 1.0.
324

An in situ spectro-electrochemical study of aluminium/polymer interfaces : development of ATR-FTIR and its integration with EIS for corrosion studies

Öhman, Maria January 2006 (has links)
<p>In order to extend the applications of aluminium, organic coatings may be applied on sheet materials, for instance for corrosion protection or aesthetic surface finish purposes in the automotive and construction industries, or on foil materials in the flexible packaging industry.</p><p>The most common mechanisms for deterioration and structural failure of organically coated aluminium structures are triggered by exposures to the surrounding environment. Despite the great importance to elucidate the influence of exposure parameters on a buried aluminium/polymer interface, there is still a lack of knowledge regarding the mechanisms that destabilise the structure. It is generally believed that a detailed <i>in situ</i> analysis of the transport of corroding species to the buried interface, or of surface processes occurring therein, is most difficult to perform at relevant climatic and real-time conditions.</p><p>In this work, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) in the Kretschmann-ATR configuration was successfully applied to <i>in situ</i> studies of the transport of water and ionic species through polymer films to the aluminium/polymer interface upon exposure to ultra pure deionised water and to a 1 M sodium thiocyanate (NaSCN) model electrolyte. Other main processes distinguished were the formation of corrosion products on the aluminium surface and swelling of the surface-near polymer network. Hence, <i>in situ</i> ATR-FTIR was capable to separate deterioration-related processes from each other.</p><p>To perform more unambiguous interpretations, a spectro-electrochemical method was also developed for<i> in situ</i> studies of the buried aluminium/polymer interface by integrating the ATR-FTIR technique with a complementary acting technique, Electrical Impedance Spectroscopy (EIS). While transport of water and electrolyte through the polymer film to the aluminium/polymer interface and subsequent oxidation/corrosion of aluminium could be followed by ATR-FTIR, the protective properties of the polymer as well as of processes at the aluminium surface were simultaneously studied by EIS. The integrated set-up provided complementary information of the aluminium/polymer sample investigated, with ATR-FTIR being sensitive to the surface-near region and EIS being sensitive to the whole system. While oxidation/corrosion and delamination are difficult to distinguish by EIS, oxide formation could be confirmed by ATR-FTIR. Additionally, while delamination and polymer swelling may be difficult to separate with ATR-FTIR, EIS distinguished swelling of the polymer network and also identified ultimate failure as a result of delamination.</p><p>The capability of the integrated ATR-FTIR / EIS <i>in situ</i> technique was explored by studying aluminium/polymer systems of varying characteristics. Differences in water and electrolyte ingress could be monitored, as well as metal corrosion, polymer swelling and delamination.</p>
325

Herstellung und Charakterisierung von dünnen Schichten im ternären System B-C-N

Linß, Volker 13 March 2003 (has links) (PDF)
Die vorliegende Arbeit beschäftigt sich mit der Herstellung und Charakterisierung von dünnen Schichten im ternären System B-C-N. In diesem System sind einerseits die härtesten heute bekannten Materialien (Diamant, c-BN) enthalten, aber andererseits auch Stoffe mit unterschiedlichsten elektrischen Eigenschaften (Graphit, h-BN). Es besteht daher das Bestreben, verschiedene bekannte Materialien zu kombinieren und so deren Eigenschaften in gewünschter Weise einzustellen. Allerdings wird sowohl experimentell als auch theoretisch des öfteren eine Separation in BN- und C/CNx-Phasen beobachtet. Im Rahmen dieser Arbeit wurden Schichten über einen weiten Stöchiometriebereich mittels reaktiver DC-Magnetronzerstäubung hergestellt und untersucht. Schwerpunkt wurde dabei auf die Analyse der Struktur und des Bindungszustandes sowie die mechanischen Eigenschaften Härte und Elastizitätsmodul gelegt. Es wird diskutiert, in welchen Elementezusammensetzungen wirkliche ternäre Verbindungen entstanden sind und ein Zusammenhang zwischen Struktur und mechanischen Eigenschaften in Form einer empirischen Formel abgeleitet.
326

Systematic study of amyloid beta peptide conformations: Implications for alzheimer's disease

Jimenez, Jeffy Pilar 01 June 2005 (has links)
The amyloid beta peptide particularly the 40 and 42 amino acid residues are the responsible for plaque formation in Alzheimer's disease (AD) patients. Extra cellular plaque formation has been recognized after incessant investigations along with the formation of intracellular tau protein tangles as the hallmarks of AD. Furthermore, the plaque formation has been linked mostly as a cause of the disease and the tangles mostly as a consequence. Our investigation is focused on studying the formation of AD plaques. The amyloid beta (A[beta]) is a physiological peptide secreted from neurons under normal conditions, along with other soluble forms cleaved from the amyloid precursor protein (APP). These soluble forms of APP have neuroprotective and neurotrophic functions, while the A[beta] is considered an unwanted by-product of the APP processing. Under normal conditions there is an anabolic/catabolic equilibrium of the A[beta] peptide; therefore, it is believed that the formation of the plaque does not take place. On the other hand, the neurons' surface may play an important role in the adhesion mechanisms of the A[beta] peptide. Our experiments show that the neuron surfaces along with the media conditions may be the most important causes for progressive formation of plaques. We have incubated rigid supports (mica) and soft biomimetic substrates (lipid bilayers on top of a PEG cushion layer drafted onto a silica surface) with the three different conformations of the A[beta] peptide (monomeric, oligomeric and fibrils structures) to determine the adhesion mechanisms associated with in situ plaque formation. The soft biomimetic substrates have been assembled first by depositing and activating a thin film of silica (i.e., to create surface silanol groups). This film is then reacted with polyethylene glycol (PEG), which is a biocompatible polymer, to create a cushion-like layer that supports and allows the lipid bilayer to have high mobility. A lipid bilayer is then deposited on this soft support to reproduce a cell membrane using the Langmuir Blodgett deposition technique. The characterization of such biomimetic membranes has been studied by using Atomic Force Microscopy (AFM) in liquid environments. Our results show that these lipid bilayers are highly mobile. Additionally the structure and topography characteristics of the A[beta] conformations have been followed with atomic force microscopy (AFM). The kinetics and rates of adhesion have been measured with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Our results show the progress of the plaques' formation with time where simple monomers deposit on the substrates and allow the development of oligomeric species.
327

Fermentation and Supercritical Extraction Studies of Açaí Berry

Ayala, Rosanna Iris 01 January 2012 (has links)
The açaí berry has grown in popularity for dieters and the health conscious. The berry contains high levels of antioxidants. The main anthocyanins are cyanidin-3-rutinoside and cyanidin-3-glucoside. The berries also contain vitamins and nutrients that help boost energy and alertness, and fatty acids that help maintain normal cholesterol levels. As a result of the health benefits of the constituents, the berries are chosen for obtaining the active ingredients by extraction. The solids left over after extraction still contain nutrients and useful components. There is a possibility of fermenting this residual and creating an açaí berry wine. Açaí berry wine is another new product on the market. The extracts and the wine are analyzed using Fourier transform infrared spectroscopy (FTIR). In an effort to utilize every part of the berry, the residual from the extract is also successfully fermented. Pilot plant studies are conducted utilizing supercritical carbon dioxide, an ethanol entrainer to increase its solubility, and subcritical water to extract components from freeze dried açaí berry. There is much potential and flexibility in the process, which effectively extracted lipids from the berry leaving behind anthocyanins without solvent residue.
328

Application and modeling of TiO2-supported gold nanoparticles for CO preferential oxidation in excess hydrogen

Grayson, Benjamin Alan 01 June 2007 (has links)
This work begins with a brief overview of heterogeneous, characterization techniques, and current hypotheses about gold mechanisms. This is followed by the initial characterization of custom two-phase-method gold nanoparticles provided by the Interfacial Phenomena and Polymeric Materials research group at USF, the anatase TiO2 support and reference Au/TiO2 catalyst provided by the World Gold Council. In order to verify the ability of the two-phase-method GNP catalyst provided to oxidize CO in excess hydrogen, it was necessary to develop an effluent testing protocol. The first experiments involved 24 hour runs to observe catalyst deactivation. Concerns over cycling effects observed in the absorbance integral calculations lead to the introduction of a reference gas. Corrections were made to the carbon monoxide absorbance integral calculations which allowed the direct comparison of results. These corrections included baseline adjustments for each species and N2 purging to eliminate background CO2 and H2O contamination. After these improvements, the two phase method GNP catalyst CO oxidation ability was investigated. Unfortunately, the supplied two phase method gold catalyst has been unresponsive for CO oxidation applications. One hypothesis for the problems is that the surfactants used to keep the gold nanoparticles from aggregating are preventing carbon monoxide transport to the surface of the particle. Another theory is that the gold may not be adhering to the surface of the TiO2 creating a cohesive metal/support interaction. The kinetics of CO preferential oxidation (PROX) catalyzed by the World Gold Council's nano-Au/TiO2 was studied to evaluate elementary and nonelementary empirical rate expressions. Information is readily available for CO fractional conversion for this catalyst below 0 degrees C. However, a comprehensive CO PROX kinetic model in which three reactions (CO oxidation, H2 oxidation and the water gas shift reaction) occur simultaneously is lacking. The reaction was carried out in a vertical packed bed micro-reactor testing unit; temperature was varied between 25 and 125 degrees C, and a range of feed rates were tested. In-situ Fourier transform infrared spectroscopy (FTIR) reaction data was analyzed; pre-exponential and activation energies are calculated for each kinetic model. Empirical rate expressions based on power law models were used to fit the experimental data. The reversible water gas shift reaction was found to play an important role when fitting the experimental data precisely and explained the selectivity decrease at higher reaction temperatures. The empirical kinetic model presented will be useful to simulate PROX operation parameters for many applications.
329

Schwingungsdynamik in O−H···O-verbrückten Aggregaten: FTIR-Spektroskopie vom Nah- bis zum Ferninfraroten / Vibrational dynamics in O–H···O connected aggregates: FTIR spectroscopy from the near to the far infrared

Kollipost, Franz 08 June 2015 (has links)
No description available.
330

Flocculation of silica particles in a model oil solution: Effect of adsorbed asphaltene

Zahabi, Atoosa Unknown Date
No description available.

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