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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.
1

Estudo in-vitro dos efeitos do laser de Er,Cr:YSGG em tecido ósseo por espectroscopia ATR-FTIR / Study in vitro of Er,Cr:YSGG laser effects in bone tissue by ATR-FTIR spectroscopy

Carolina Benetti 23 April 2010 (has links)
O laser tem se mostrado eficaz no auxílio ao profissional de saúde, sendo extensivamente utilizado em procedimentos médicos e odontológicos nas ultimas décadas. Em particular, os lasers de alta intensidade emissores no infravermelho possuem grande potencial para corte de tecidos biológicos mineralizados, visto que são bastante absorvidos pela hidroxiapatita e água, principais componentes desses tecidos. Em comparação aos instrumentos mecânicos, o laser apresenta uma série de vantagens no corte de tecidos, com possibilidade de menor dano ao tecido remanescente e melhor hemostasia. Entretanto, para uma aplicação eficiente e segura é necessário conhecer os efeitos que a irradiação laser causa ao tecido. A técnica de espectroscopia no Infravermelho por Transformada de Fourier (FTIR) é bastante utilizada no estudo de materiais orgânicos, pois além de permitir a identificação de componentes, possibilita uma análise semiquantitativa. Este trabalho tem como objetivos estabelecer a técnica de ATR-FTIR para caracterização do tecido ósseo natural e irradiado, e verificar as eventuais mudanças químicas e estruturais causadas pela irradiação laser. Primeiramente, foram determinadas as melhores condições instrumentais para a obtenção dos espectros de amostras de osso. Posteriormente foram analisadas as amostras de osso natural e irradiado com o laser de Er,Cr:YSGG (2,78 μm) com diferentes densidades de energia. Verificou-se que a técnica foi eficaz na caracterização do tecido ósseo, sendo possível observar as alterações químicas promovidas pelo aumento de temperatura ocasionado pela irradiação laser. Foi observada a perda gradativa de material orgânico em função do aumento da densidade de energia utilizada. Os resultados obidos são os primeiros passos para a verificação da eficácia do laser de Er,Cr:YSGG quando empregado como uma ferramenta de corte, essencial para sua consolidação na prática clínica. / Laser proves to be, more and more, an effective tool for helping health professionals, being intensively used in ophthalmological and odontological procedures. In particular, high-density, infrared emitting lasers have great potential in cutting mineralized biological hard tissues, given their high absorption by hydroxyapatite and water, these tissues main components. In comparison to mechanical instruments, laser presents a series of advantages, namely, smaller damage to the remaining tissue and promotion of homeostatic effect, apart from making it possible to execute procedures in areas with difficult access. However, for an efficient and safe use of this technique, it is necessary to know the effects of the laser irradiation on the tissue. The Fourier transform infrared (FTIR) technique is heavily used in the study of organic materials, because apart from making it possible to identify the materials components, it also allows to prepare a semi quantitative analysis. This work aims to establish the ATR-FTIR technique in the characterization of natural and irradiated osseous tissue, and to verify the possible chemical and structural changes caused by irradiation. Firstly, the best conditions for the obtainment of bone sample spectra were determined. Then, bone samples, irradiated with the Er,Cr:YSGG (2,78 μm) infrared emitting laser (adjusted with different energy densities) were analyzed alongside with natural bone samples. It has been verified that the technique is effective in the bone tissue characterization, and that it is possible to observe the chemical changes caused by the temperature rise due to laser irradiation. It has been observed a gradual organic material loss as the energy density goes up. These results are the first steps in testing the Er,Cr:YSGG laser efficacy as a cutting tool, a pivotal aspect of its consolidation in clinical procedures.
2

Estudo in-vitro dos efeitos do laser de Er,Cr:YSGG em tecido ósseo por espectroscopia ATR-FTIR / Study in vitro of Er,Cr:YSGG laser effects in bone tissue by ATR-FTIR spectroscopy

Benetti, Carolina 23 April 2010 (has links)
O laser tem se mostrado eficaz no auxílio ao profissional de saúde, sendo extensivamente utilizado em procedimentos médicos e odontológicos nas ultimas décadas. Em particular, os lasers de alta intensidade emissores no infravermelho possuem grande potencial para corte de tecidos biológicos mineralizados, visto que são bastante absorvidos pela hidroxiapatita e água, principais componentes desses tecidos. Em comparação aos instrumentos mecânicos, o laser apresenta uma série de vantagens no corte de tecidos, com possibilidade de menor dano ao tecido remanescente e melhor hemostasia. Entretanto, para uma aplicação eficiente e segura é necessário conhecer os efeitos que a irradiação laser causa ao tecido. A técnica de espectroscopia no Infravermelho por Transformada de Fourier (FTIR) é bastante utilizada no estudo de materiais orgânicos, pois além de permitir a identificação de componentes, possibilita uma análise semiquantitativa. Este trabalho tem como objetivos estabelecer a técnica de ATR-FTIR para caracterização do tecido ósseo natural e irradiado, e verificar as eventuais mudanças químicas e estruturais causadas pela irradiação laser. Primeiramente, foram determinadas as melhores condições instrumentais para a obtenção dos espectros de amostras de osso. Posteriormente foram analisadas as amostras de osso natural e irradiado com o laser de Er,Cr:YSGG (2,78 μm) com diferentes densidades de energia. Verificou-se que a técnica foi eficaz na caracterização do tecido ósseo, sendo possível observar as alterações químicas promovidas pelo aumento de temperatura ocasionado pela irradiação laser. Foi observada a perda gradativa de material orgânico em função do aumento da densidade de energia utilizada. Os resultados obidos são os primeiros passos para a verificação da eficácia do laser de Er,Cr:YSGG quando empregado como uma ferramenta de corte, essencial para sua consolidação na prática clínica. / Laser proves to be, more and more, an effective tool for helping health professionals, being intensively used in ophthalmological and odontological procedures. In particular, high-density, infrared emitting lasers have great potential in cutting mineralized biological hard tissues, given their high absorption by hydroxyapatite and water, these tissues main components. In comparison to mechanical instruments, laser presents a series of advantages, namely, smaller damage to the remaining tissue and promotion of homeostatic effect, apart from making it possible to execute procedures in areas with difficult access. However, for an efficient and safe use of this technique, it is necessary to know the effects of the laser irradiation on the tissue. The Fourier transform infrared (FTIR) technique is heavily used in the study of organic materials, because apart from making it possible to identify the materials components, it also allows to prepare a semi quantitative analysis. This work aims to establish the ATR-FTIR technique in the characterization of natural and irradiated osseous tissue, and to verify the possible chemical and structural changes caused by irradiation. Firstly, the best conditions for the obtainment of bone sample spectra were determined. Then, bone samples, irradiated with the Er,Cr:YSGG (2,78 μm) infrared emitting laser (adjusted with different energy densities) were analyzed alongside with natural bone samples. It has been verified that the technique is effective in the bone tissue characterization, and that it is possible to observe the chemical changes caused by the temperature rise due to laser irradiation. It has been observed a gradual organic material loss as the energy density goes up. These results are the first steps in testing the Er,Cr:YSGG laser efficacy as a cutting tool, a pivotal aspect of its consolidation in clinical procedures.
3

The Effects Of Selenium On Stz-induced Diabetic Rat Kidney Plasma Membrane

Gurbanov, Rafig 01 January 2010 (has links) (PDF)
The kidney is one of the most affected organs of body from diabetes. Diabetic kidney disease is a complication of diabetes seen in 30-40% of diabetic person. The aim of this work is to contribute the useful information in the therapy of diabetes. It is very important to know the role of antioxidants at the molecular level during diabetes. The protecting role of antioxidants against lipid peroxidation, the effect of cellular antioxidant enzyme systems, understanding the changes of membrane fluidity, lipid order and protein structure which are resulted from antioxidant treatment, determining the effective therapeutic dose with the help of biochemical methods are very important in order to understand the effect of antioxidants at molecular level. In this thesis work, the Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) was used in order to study the diabetic kidney disease at the molecular level, which is encountered as a complication of diabetes. Furthermore, the protecting and possible therapeutic role of selenium in the course of diabetic kidney disease was investigated. To conclude, the kidney plasma membranes were severely deteriorated due to diabetes with respect to its lipid, protein and carbohydrate structure and content, which were corrected after selenium treatment. The diabetes causes diminishment of whole membrane fluidity, which was normalized with the selenium administration. This is the first study demonstrating the effect of diabetes on kidney plasma membrane and the effect of selenium on stz-induced diabetic kidney plasma membranes using spectroscopic tools. The study revealed serious therapeutic and preventing capacities of selenium on diabetic kidney plasma membranes which needs confirmation of future researches. Furthermore, the dosage of selenium given to diabetics should be investigated in detail and proved with biochemical and clinical data.
4

The Molecular Investigation Of The Effects Of Simvastatin, A Cholesterol Reducing Drug, On Different Rat Skeletal Muscle Tissues

Simsek Ozek, Nihal 01 September 2007 (has links) (PDF)
In the present study Fourier Transform Infrared (FTIR) and Attenuated Total Reflectance FTIR (ATR-FTIR) Spectroscopy were used to examine the effects of simvastatin on structure, composition and function of macromolecules of three different rat skeletal muscles EDL (Extensor Digitorium Longus), DIA (Diaphragm) and SOL (Soleus) containing different amount of slow and fast twitch fibers, at molecular level. Simvastatin, a lipophilic statin, is widely used in the treatment of hypercholesterolemia and cardiovascular diseases due to its higher efficacy. However, long term usage of statins give rise to many adverse effects on different tissues and organs. Skeletal muscle accounts for around 45 % of the total body weight and has a high metabolic rate and blood flow. As a consequence, it is highly exposed to drugs within the circulation. Therefore, it is one of the target tissues of statins. The two main types of muscle fibers are type I (slow-twitch) and type II (fast-twitch) fibers / having different structural organization and metabolic features. EDL is a fast twitch muscle while SOL is slow twitch muscle. On the other hand, DIA shows intermediate properties between slow and fast twitch muscle. The results of ATR-FTIR and FTIR spectra revealed a considerable decrease in protein and lipid content of simvastatin treated skeletal muscles, indicating protein breakdown or decreased protein synthesis and increased lipolysis. Moreover changes in protein structure and conformation were observed. In simvastatin treatment, muscle membrane lipids were more ordered and the amount of unsaturated lipids was decreased possibly due to lipid peroxidation. The drug treatment caused a decrease in the content of nucleic acids, especially RNA, and hydrogen and non-hydrogen bonded phospholipids in the membrane structures of skeletal muscles. In all of the spectral parameters investigated EDL muscle was more severely affected from statin treatments while SOL was less affected from the drug treatments. Thus, FTIR and ATR-FTIR spectroscopy appear to be useful methods to evaluate the effects of statin on skeletal muscle tissues at molecular level.
5

Characterization Of Yellow Rust And Stem Rust Resistant And Sensitive Durum Wheat Lines At Molecular Level By Using Biophysical Methods

Kansu, Cigdem 01 September 2011 (has links) (PDF)
Stem rust and Yellow rust diseases are the two major wheat fungal diseases causing considerable yield losses in Turkey and all around the world. There are studies which are carried out to identify and utilize resistance sources in order to obtain resistant lines of wheat. However, virulent pathotypes are continuously being important threats to wheat production and yield. For that reason, new approaches for rapid identification are needed. The aim of this study was to investigate and to understand the structural and functional differences between the resistant and sensitive durum wheat cultivars to the plant fungal diseases of stem and yellow (stripe) rusts. To aim this, forty durum wheat recombinant inbred lines (RILs), which were previously determined to be resistant or sensitive to stem and yellow rust diseases, were investigated by the noninvasive Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectroscopy. Also, classification of the resistant and sensitive lines depending on the structural and functional differences has been attempted. The FTIR spectra for stem rust disease showed that, resistant durum wheat lines had a significant increase in the population of unsaturation in acyl chains of lipid molecules, an increase in lipid and in total protein content and also an increase in carboxylic acids and alcohols. For yellow rust disease, resistant lines had a significant increase in hydrogen bonding and they had also a more ordered membrane structure. In Principal Component Analysis for stem rust disease, according to 3700-650 cm-1 region, amide III band (1213-1273 cm-1 region) and C-H stretching region (3020- 2800 cm-1), the resistant and sensitive groups were separated successfully. For yellow rust disease, according to 3700-650 cm-1 region, Amide A and Amide III bands, the resistant and sensitive lines were grouped distinctly. FTIR spectroscopy provides a useful approach to determine the differences in molecular structure of durum wheat RILs regarding resistance of lines to fungal diseases. However, further research is still needed to ensure if the structural and functional differences in biomolecules of the samples could be used as molecular markers for discrimination of rust resistant materials from rust sensitive ones.
6

The Effects Of Streptozotocin Induced-diabetes On Rat Testes And The Recovery Role Of Vitamin C

Guldag, Damla 01 January 2012 (has links) (PDF)
Type I Diabetes is a multisystem disease having both biochemical and structural consequences. It causes alterations in carbohydrate, protein, and fat metabolisms due to hyperglycemia. Type I diabetes is also correlated with increased formation of free radicals and decreased levels of antioxidant potential. Lower endogeneous antioxidant amounts and elevated lipid peroxidation levels in diabetes constitute the basis of risk factors for the development of diabetic complications. These complications lead to irreversible damages in nearly all vital organs and systems. Since the antioxidant capacity lowered in diabetic conditions, it becomes important to be able to use some common antioxidants, as a complementary treatment strategy for diabetes. The effect of type I diabetes and the recovery role of Vitamin C on the structure, composition and function of the macromolecular content of testicular tissue is still unknown. Therefore, in the current study, it was aimed to investigate the alterations in the macromolecules of rat testes due to Streptozotocin (STZ)-induced type I diabetes using Attenuated Total Reflectance (ATR)-Fourier Transform Infrared (FTIR) spectroscopic and FTIR microspectroscopic techniques. Furthermore it was iv aimed to gain useful information about the recovery role of Vitamin C, as an antioxidant, against the diabetic complications. The detailed spectral analysis revealed that, the macromolecular structure and composition of rat testes are highly affected due to the development of diabetes. The lipid and protein content of diabetic rat testes were shown to decrease considerably, indicating an increase in lipolysis and proteolysis processes. Diabetes was also shown to lead to a decrease in the content of fatty acids and nucleic acids. In addition to the compositional alterations, protein conformation, and protein secondary structural components were also found to alter in diabetic state. Besides, lipid peroxidation levels were found to increase, and the elevated levels of lipid peroxidation products end up with increased levels of unsaturation, and also end up with increased levels of disorderness in diabetic conditions. On the other hand, with the administration of Vitamin C, the diabetes-induced alterations were found to be partially recovered, indicating that after more confirmative researches, Vitamin C may have a chance to be used as a complementary therapy in the treatment of diabetes.
7

Etude expérimentale et modélisation par bilans de populations des cinétiques de nucléation de croissance d’opérations discontinues de cristallisation par refroidissement en absence et en présence d’impuretés. / Experimental study and by population balances modeling of batch cooling crystallization kinetics in the absence and presence of impurities.

Gherras, Nesrine 22 December 2011 (has links)
De façon évidente, la pratique industrielle de la cristallisation ne peut éviter la présence d’impuretés indésirables produites suite aux nombreuses réactions chimiques précédant les étapes de cristallisation. Même en quantités infimes, les impuretés présentes dans les jus mères peuvent affecter de façon considérable la cristallisation et la qualité du produit obtenu. Dans ce contexte, les technologies de mesures en ligne fournissent un apport considérable en permettant l’obtention d’informations riches, en temps réel et de façon quasi-continue sur l’évolution des phases liquide et dispersée. L’objectif du présent travail est la compréhension des effets des impuretés sur les produits de cristallisations discontinues. Des expériences sont effectuées, sur une installation-pilote, en vue d’étudier les effets des paramètres opératoires de cristallisation de l’oxalate d’ammonium monohydrate pur et en présence de sulfate de nickel (impureté) sur la taille et la forme des cristaux produits. Pour cela, deux techniques analytiques in situ, la spectroscopie ATR FTIR pour la mesure de sursaturation et l'analyse d’image in situ pour l’évaluation des distributions des tailles des cristaux, seront utilisées. A partir des données expérimentales obtenues, nous proposons des modèles cinétiques de nucléation (primaire et secondaire) et de croissance tenant compte de l'action des impuretés et décrivant l’adsorption de celles-ci à la surface des cristaux. Ces modèles sont ensuite exploités pour la mise en place de simulations fondées sur les équations de bilans de populations.L’originalité de l’approche adoptée réside dans l’emploi du modèle classique de Kubota – Mullin, modifié par l’ajout d’une variable temporelle permettant la prise en compte de la durée d’exposition de chaque cristal aux impuretés. Les résultats de simulation obtenus décrivent de façon satisfaisante l’évolution temporelle de la sursaturation et de la distribution de taille des cristaux. / Hindering effects of impurities on crystal growth are usually assumed to result in the adsorption of impurity species on the crystal surface. In the presence of impurities the growth rate does not depend on supersaturation only, but also on the concentration in impurities and on the contact time of a given particle with inhibiting species (unsteady-state adsorption mechanisms). Few kinetic models describe such phenomena. Indeed, for process engineering purposes, the available kinetic inhibition models accounting for the effect of impurities (e.g. Kubota-Mullin’s approaches), have to be evaluated in industrial situations where complex and distributed features of the crystallizing suspensions are involved (e.g. during batch solution crystallization). Population Balance Equations (PBE) modeling offers an invaluable simulation tool for such evaluation.With this aim in view, a comprehensive modeling approach based on in situ continuous and dispersed phase measurements, and specific PBE simulation was developed to represent and better understand the effect of impurities on the development of batch crystallization processes.Cooling solution crystallization of Ammonium Oxalate (AO) in water in the absence and presence of Nickel Sulphate at different concentrations was selected as a model system during this study. In situ measurements of supersaturation were performed using ATRFTIR spectroscopy and the CSD was assessed thanks to in situ image acquisition. The experimental results were simulated after estimating crystallization kinetic parameters, including parameters of models describing the inhibiting adsorption of impurity on the growing crystal surfaces. Primary and secondary surface nucleation mechanisms as well as growth of the main crystal dimension (length) were described in pure and impure media. The model roughly represents the effects of different cooling rates and impurity concentration on the supersaturation profiles and the CSD of the final particles.
8

Characterization of microplastics in wastewater

Sabienski, Lina January 2020 (has links)
This study aims to detect how many microplastics and what kind are released from the wastewater treatment plant (WWTP) Skebäck, in Örebro. The study was limited to the analysis of three filters with 50 μm mesh size and one filter with 300 μm mesh size. The samples were taken at different times, two in the fall of 2019 and one in the spring of 2020. Visual characterization was used for the quantification of microplastics, and a lower and upper bound was used. The lower bound represents particles that were deemed identifiable as plastic with high certainty, while the upper bound also includes particles that may have been microplastic. An additional ATR-FTIR analysis was performed on selected microplastics >300 μm.  The presence of microplastics in the effluent from Skebäcks WWTP could be confirmed. The quantity of microplastics per m​3​ (MP/m​3​) trapped on the 50 μm filters were quantified in a range between 0 MP/m​3​ to 291 MP/m​3​ for the lower bound, and 72 MP/m​3​ to 435 MP/m​3​ for the upper bound. The 300 μm filter had considerably less microplastics than the 50 μm filter with 1.8 MP/m​3​. The quantification of fibers on the 50 μm filter and 300 μm filters was not possible due to high blank contaminations. According to the concentration of 63 MP/m​3​ of the lower bound count on the 50 μm filters and the amount of water flowing through Skebäck in 2019, 17 818 935 m​3​, 1.1 billion microplastic particles were released into Svartån that year. In comparison the highest value of the upper bound count, 435 MP/m​3​, gave a release of 7.7 billion microplastic particles. Using the concentration of the 300 μm filter 1.8 MP/m​3​, 32 million microplastics/year were released from Skebäck in 2019. The amount of spheres 50-300 μm released in the effluent from Skebäck was estimated to be 3.7 kg in 2019.
9

A study on the thermal stability of sodium dithionite using ATR-FTIR spectroscopy / A study on the thermal stability of sodium dithionite using ATR-FTIR spectroscopy

Vegunta, Vijaya Lakshmi January 2016 (has links)
Sodium dithionite (Na2S2O4) is a powerful reducing agent. It has therefore been suggested to be used as an additive in kraft pulping to improve the yield. However, sodium dithionite easily decomposes and it is thus important to determine the effect of different conditions. The aim of this thesis has been to investigate the thermal stability of sodium dithionite under anaerobic conditions using ATR-FTIR spectroscopy under different conditions, such as heating temperature, concentration of the solution, heating time and pH. The stability of sodium dithionite was found to decrease with increasing heating temperature, concentration of sodium dithionite, heating time and pH. Sodium dithionite was found to be relatively stable at moderate alkaline pH:s 11.5 and 12.5, while a rapid decrease in stability with time was noted at higher heating temperatures and concentrations of sodium dithionite. Based on this study on the thermal stability of sodium dithionite, the following conditions are suggested as the most promising, when adding sodium dithionite to the kraft cooking as an additive; pH 12.5, with 0.4 M concentration of the solution, at a heating temperature of 100 °C.
10

Degradation of polymer/substrate interfaces - an attenuated total reflection Fourier transform infrared spectroscopy approach

Ghosh, Arijit 17 December 2010 (has links)
No description available.

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