Evaluation of thermal remote sensing for detection of thermal anomalies as earthquake precursors: a case study for Malatya-Pütürge-Doganyol (Turkey) Earthquake, July 13, 2003

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

Mécanismes de déformation de nanoparticules d’Au par irradiation ionique

Résumé Dans la présente thèse, nous avons étudié la déformation anisotrope par bombardement ionique de nanoparticules d'or intégrées dans une matrice de silice amorphe ou d'arséniure d’aluminium cristallin. On s’est intéressé à la compréhension du mécanisme responsable de cette déformation pour lever toute ambigüité quant à l’explication de ce phénomène et pour avoir une interprétation consistante et unique. Un procédé hybride combinant la pulvérisation et le dépôt chimique en phase vapeur assisté par plasma a été utilisé pour la fabrication de couches nanocomposites Au/SiO2 sur des substrats de silice fondue. Des structures à couches simples et multiples ont été obtenues. Le chauffage pendant ou après le dépôt active l’agglomération des atomes d’Au et par conséquent favorise la croissance des nanoparticules. Les nanocomposites Au/AlAs ont été obtenus par implantation ionique de couches d’AlAs suivie de recuit thermique rapide. Les échantillons des deux nanocomposites refroidis avec de l’azote liquide ont été irradiés avec des faisceaux de Cu, de Si, d’Au ou d’In d’énergie allant de 2 à 40 MeV, aux fluences s'étendant de 1×1013 à 4×1015 ions/cm2, en utilisant le Tandem ou le Tandetron. Les propriétés structurales et morphologiques du nanocomposite Au/SiO2 sont extraites en utilisant des techniques optiques car la fréquence et la largeur de la résonance plasmon de surface dépendent de la forme et de la taille des nanoparticules, de leur concentration et de la distance qui les séparent ainsi que des propriétés diélectriques du matériau dans lequel les particules sont intégrées. La cristallinité de l’arséniure d’aluminium est étudiée par deux techniques: spectroscopie Raman et spectrométrie de rétrodiffusion Rutherford en mode canalisation (RBS/canalisation). La quantité d’Au dans les couches nanocomposites est déduite des résultats RBS. La distribution de taille et l’étude de la transformation de forme des nanoparticules métalliques dans les deux nanocomposites sont déterminées par microscopie électronique en transmission. Les résultats obtenus dans le cadre de ce travail ont fait l’objet de trois articles de revue. La première publication montre la possibilité de manipuler la position spectrale et la largeur de la bande d’absorption des nanoparticules d’or dans les nanocomposites Au/SiO2 en modifiant leur structure (forme, taille et distance entre particules). Les nanoparticules d’Au obtenues sont presque sphériques. La bande d’absorption plasmon de surface (PS) correspondante aux particules distantes est située à 520 nm. Lorsque la distance entre les particules est réduite, l’interaction dipolaire augmente ce qui élargit la bande de PS et la déplace vers le rouge (602 nm). Après irradiation ionique, les nanoparticules sphériques se transforment en ellipsoïdes alignés suivant la direction du faisceau. La bande d’absorption se divise en deux bandes : transversale et longitudinale. La bande correspondante au petit axe (transversale) est décalée vers le bleu et celle correspondante au grand axe (longitudinale) est décalée vers le rouge indiquant l’élongation des particules d’Au dans la direction du faisceau. Le deuxième article est consacré au rôle crucial de la déformation plastique de la matrice et à l’importance de la mobilité des atomes métalliques dans la déformation anisotrope des nanoparticules d’Au dans les nanocomposites Au/SiO2. Nos mesures montrent qu'une valeur seuil de 2 keV/nm (dans le pouvoir d'arrêt électronique) est nécessaire pour la déformation des nanoparticules d'or. Cette valeur est proche de celle requise pour la déformation de la silice. La mobilité des atomes d’Au lors du passage d’ions est confirmée par le calcul de la température dans les traces ioniques. Le troisième papier traite la tentative de formation et de déformation des nanoparticules d’Au dans une matrice d’arséniure d’aluminium cristallin connue pour sa haute résistance à l’amorphisation et à la déformation sous bombardement ionique. Le résultat principal de ce dernier article confirme le rôle essentiel de la matrice. Il s'avère que la déformation anisotrope du matériau environnant est indispensable pour la déformation des nanoparticules d’or. Les résultats expérimentaux mentionnés ci-haut et les calculs de températures dans les traces ioniques nous ont permis de proposer le scénario de déformation anisotrope des nanoparticules d’Au dans le nanocomposite Au/SiO2 suivant: - Chaque ion traversant la silice fait fondre brièvement un cylindre étroit autour de sa trajectoire formant ainsi une trace latente. Ceci a été confirmé par la valeur seuil du pouvoir d’arrêt électronique. - L’effet cumulatif des impacts de plusieurs ions conduit à la croissance anisotrope de la silice qui se contracte dans la direction du faisceau et s’allonge dans la direction perpendiculaire. Le modèle de chevauchement des traces ioniques (overlap en anglais) a été utilisé pour valider ce phénomène. - La déformation de la silice génère des contraintes qui agissent sur les nanoparticules dans les plans perpendiculaires à la trajectoire de l’ion. Afin d’accommoder ces contraintes les nanoparticules d’Au se déforment dans la direction du faisceau. - La déformation de l’or se produit lorsqu’il est traversé par un ion induisant la fusion d’un cylindre autour de sa trajectoire. La mobilité des atomes d’or a été confirmée par le calcul de la température équivalente à l’énergie déposée dans le matériau par les ions incidents. Le scénario ci-haut est compatible avec nos données expérimentales obtenues dans le cas du nanocomposite Au/SiO2. Il est appuyé par le fait que les nanoparticules d’Au ne se déforment pas lorsqu’elles sont intégrées dans l’AlAs résistant à la déformation.

Proper evaluation of the external convective heat transfer for the thermal analysis of cool roofs

Cool materials are characterized by high solar reflectance and high thermal emittance; when applied to the external surface of a roof, they make it possible to limit the amount of solar irradiance absorbed by the roof, and to increase the rate of heat flux emitted by irradiation to the environment, especially during nighttime. However, a roof also releases heat by convection on its external surface; this mechanism is not negligible, and an incorrect evaluation of its entity might introduce significant inaccuracy in the assessment of the thermal performance of a cool roof, in terms of surface temperature and rate of heat flux transferred to the indoors. This issue is particularly relevant in numerical simulations, which are essential in the design stage, therefore it deserves adequate attention. In the present paper, a review of the most common algorithms used for the calculation of the convective heat transfer coefficient due to wind on horizontal building surfaces is presented. Then, with reference to a case study in Italy, the simulated results are compared to the outcomes of a measurement campaign. Hence, the most appropriate algorithms for the convective coefficient are identified, and the errors deriving by an incorrect selection of this coefficient are discussed.

X-ray and gamma irradiation effects on dipole defects in CaF2 : La, Yb, Al

Impurity-interstitial dipoles in calcium fluoride solutions with Al3+, Yb3+ and La3+ fluorides were studied using the thermally stimulated depolarization current (TSDC) technique. The dipolar complexes are formed by substitutional trivalent ions in Ca2+ sites and interstitial fluorine in nearest neighbor sites. The relaxations observed at 150 K are assigned to dipoles nnR(S)(3+)- F-i(-) (R-S = La or Yb). The purpose of this work is to study the processes of energy storage in the fluorides following X-ray and gamma irradiation. Computer modelling techniques are used to obtain the formation energy of dipole defects. (C) 2007 Elsevier Ltd. All rights reserved.

Thermal characterization of dental composites by TG/DTG and DSC

Dental composites can be improved by heat treatment, as a possible way to increase mechanical properties due to additional cure (post-cure). Direct dental composites are essentially similar to the indirect ones, supposing they have the same indication. Therefore, to establish a heat treatment protocol for direct composites, using as indirect (photoactivated by continuous and pulse-delay techniques), a characterization (TG/DTG and DSC) is necessary to determine parameters, such as mass loss by thermal decomposition, heat of reaction and glass transition temperature (T (g)). By the results of this study, a heat treatment could be carried out above 160 A degrees C (above T (g), and even higher than the endset exothermic event) and under 180 A degrees C (temperature of significant initial mass loss).

Mechanical, thermal and morphological characterization of polypropylene/biodegradable polyester blends with additives

The (bio)degradation of polyolefins can be accelerated by modifying the level of crystallinity or by incorporation of carbonyl groups by adding pro-oxidants to masterbatches or through exposure to ultraviolet irradiation. In this work we sought to improve the degradation of PP by adding cobalt, calcium or magnesium stearate to Ecoflex(R), PP or Ecoflex(R)/PP blends. The effect of the pro-oxidants on biodegradability was assessed by examining the mechanical properties and fluidity of the polymers. PP had higher values for tensile strength at break and Young`s modulus than Ecoflex(R), and the latter had little influence on the properties of PP in Ecoflex(R)/PP blends. However, the presence of pro-oxidants (except for calcium) reduced these properties. All of the pro-oxidants enhanced the fluidity of PP, a phenomenon that facilitated polymer degradation at high temperatures. (C) 2009 Elsevier Ltd. All rights reserved.

Load Adapted Solar Thermal Combisystems - Optical Analysis and Systems Optimization

In a northern European climate a typical solar combisystem for a single family house normally saves between 10 and 30 % of the auxiliary energy needed for space heating and domestic water heating. It is considered uneconomical to dimension systems for higher energy savings. Overheating problems may also occur. One way of avoiding these problems is to use a collector that is designed so that it has a low optical efficiency in summer, when the solar elevation is high and the load is small, and a high optical efficiency in early spring and late fall when the solar elevation is low and the load is large.The study investigates the possibilities to design the system and, in particular, the collector optics, in order to match the system performance with the yearly variations of the heating load and the solar irradiation. It seems possible to design practically viable load adapted collectors, and to use them for whole roofs ( 40 m2) without causing more overheating stress on the system than with a standard 10 m2 system. The load adapted collectors collect roughly as much energy per unit area as flat plate collectors, but they may be produced at a lower cost due to lower material costs. There is an additional potential for a cost reduction since it is possible to design the load adapted collector for low stagnation temperatures making it possible to use less expensive materials. One and the same collector design is suitable for a wide range of system sizes and roof inclinations. The report contains descriptions of optimized collector designs, properties of realistic collectors, and results of calculations of system output, stagnation performance and cost performance. Appropriate computer tools for optical analysis, optimization of collectors in systems and a very fast simulation model have been developed.

Effect of microwave irradiation and water storage on the viscoelastic properties of denture base and reline acrylic resins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The influence of UV-C irradiation on the properties of thermoplastic starch and polycaprolactone biocomposite with sisal bleached fibers

The effect of UV-C irradiation of the TPS and PCL biocomposites with sisal bleached fibers was investigated. The biocomposite was UV-C irradiated at room temperature under air atmosphere. The structural and morphological changes produced when the films were exposed to UV irradiation for 142 h, were monitored using Scanning Electron Microscopy (SEM), Mechanical Tensile Tests, Differential Scanning Calorimetry (DSC), X-ray diffraction, Thermogravimetric analysis (TGA), and Fourier transform infra-red analysis (FTIR). Addition of 5-10% fibers in composites exhibited improved mechanical and thermal properties attributed to more efficient dispersibility of fiber in the matrix and good compatibility between fibers and the matrix polymer, however, after irradiated, the tensile properties decreased due to chain scission. The samples of irradiated PCL and IFS showed crystallinity increase, whereas the blend and composites showed a decrease in crystallinity. The DSC and X-ray diffraction studies suggested interaction between polymers in the blend via carboxyl groups in thermoplastic starch-PCL and hydroxyl groups in fibers. (C) 2011 Elsevier Ltd. All rights reserved.

Assessment of external root temperature during root canal irradiation by Nd:YAG and Er:YAG lasers

Different types of laser have been widely studied for applicability in the oral health area. In the endodontic area, investigations with some types of laser have been conducted to establish safe parameters for clinical application in root canals. However, it has not been duly explained whether the temperature increase caused by laser irradiation could cause alteration in the temperature on the external surface of the root and, consequently, alterations in the cells of the periodontal ligament, causing resorption and even loss of the dental element. The proposal in this paper was to gauge the external root temperature in the apical and cervical regions of the roots of human teeth during root canal irradiation with Nd:yttrium aluminum garnet (YAG) and Er:YAG lasers using different parameters. The novel approach of this paper is the use of the technique of laser applications along the total length of the root canal with series of repetitive irradiation, however, using time of 1 s of irradiation associated with 1 s off to avoid cumulative thermal effects. Experimental results confirm the accuracy of the parameters and exposure regimen obtained. All the parameters used in this paper are acceptable from a clinical as well as a biological point of view. (C) 2009 Laser Institute of America.

Effect of lactic acid and UV irradiation on the cassava and corn starches

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of the U-238 spontaneous fission decay constant without neutron irradiation

We have developed a methodology for measuring the decay constant of the spontaneous fission of U-238, lambda(f), using nuclear particle track detectors where thermal neutron irradiation is unnecessary. This methodology is based on the fact that the radiation damage caused by spontaneous fission of trans-uranium elements bearing a mass number close to 238 are similar to U-238 spontaneous-fission ones. Loading a thick source of uranium (thickness greater than the fission fragment range) with a small amount of a suitable trans-uranium element (for instance, Pu-242, which presents a spontaneous fission half-life of 6.75(.)10(10) y), it is possible to determine the observation efficiency of a particle-track detector for fission fragments. Procedures concerning our thick source manufacture and uniformity tests of the trans-uranium distribution are also presented. These results make it possible for the exposure of thick uranium sources (without trans-uranium element) to lead to a lambda(f) value.

An eco-friendly protocol for synthesis of thiourea derivatives: 1-benzoyl-3-benzylguanidine and 1-benzoyl-3-benzyl-O-ethylisourea. A possible non-purely thermal microwave assisted reaction

1-Benzoyl-3-benzylguanidine and 1-benzoyl-3-benzyl-O-ethylisourea were synthesized in good yields (68 and 76%, respectively) from 1-benzoyl-3-benzylthiourea and benzoyl-ethylthiocarbamate in dry media conditions using KF-Al2O3 under microwave irradiation. Strong nucleophilic amines promoted the sulfur elimination by attack on the thiocarbonyl group in both thiourea and thiocarbamates to afford guanidines and isourea, respectively. Transesterification products were obtained from p-TsOH catalyzed reaction of thiocarbamate with alcohols under MW-solvent-free conditions. Very important non-purely thermal MW specific effects were evidenced and attributed to stabilization by coulombic interactions between materials and waves. (c) 2005 Elsevier Ltd. All rights reserved.

Thermal and photochemical stability of poly(vinyl alcohol)/modified lignin blends

A kraft lignin derivative (KLD) obtained by reaction with p-aminobenzoic acid/phthalic anhydride was blended with poly(vinyl alcohol) (PVA) by solution casting from DMSO. PVA and PVA/KLD films were exposed to ultraviolet radiation (24, 48, and 96 h) and analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (H-1 NMR) spectroscopy, and scanning electron microscopy (SEM). PVA films show a loss of thermal stability due to irradiation. PVA/KLD reveals greater thermal stability than PVA and an increase in thermal stability after irradiation. These results suggest that the incorporation of KLD into PVA provides a gain in thermal and photochemical stability. FTIR, H-1 NMR, DSC, and TG results obtained for the blends suggest that intermolecular interactions between PVA and KLD chains are present. SEM micrographs revealed blend miscibility for a KLD blend content of up to 15 wt%, as observed at magnification of 1000 times. (c) 2005 Elsevier Ltd. All rights reserved.

Intrapulpar temperature during continuous CO2 laser irradiation in human molars: An in vitro study

To establish safety parameters, we in vitro studied the increase in intrapulpal temperature caused by the use of a cw CO2 laser. A thermistor was implanted in the inner part of the pulpal chamber of 25 human lower third molars to measure the intrapulpal temperature produced by laser powers between 2-10 W and exposure times of 0.5-25.0 s. The Pearson linear correlation factor applied to the measured values showed there is a direct relationship between the independent variable and the applied power. A variance analysis produced the linear regression equation: T=1.10+(0.127)E where T is the temperature and E the energy. The results showed that, with a power of 4 W and maximum exposure time of 2.5 s (10 J) and a power density of 12738.85 W cm-2, there will be no damaging reactions affecting the pulpal tissues.