A Gerência de Rejeitos Radioativos do IPEN já se utiliza da técnica de ablação por laser para descontaminação de peças superficialmente contaminadas por material radioativo. Esta tecnologia, porém, demonstrou grande potencial para caracterização destes rejeitos com o objetivo de levantar o Inventário Radioisotópico de peças. As técnicas atuais para levantar este inventário (esfregaço e modelagem físico-matemática) sofrem de grandes limitações de implementação e de precisão. O objetivo deste trabalho é desenvolver o projeto de uma sonda de ablação por laser acoplada a um módulo de sucção e captura por filtro do particulado ejetado na ablação, permitindo envio do filtro para análise de emissões radioativas para classificação de radioisótopos. / The department Gerência de Rejeitos Radioativos (Radioactive Waste Management) from IPEN has already used the laser ablation technique for superficial decontamination of parts. This technique has also shown great potential for characterization of this waste with the purpose of rising data for the Radioisotopic Inventory of parts. The current techniques for this purpose (wipe sampling and physical modeling) lack the accuracy and practicality. The objective of this study is to develop the project of an instrument of laser ablation engaged with a module for sucking and capturing (by filter) the particulate ejected from the ablation, allowing the filter to be analyzed in laboratory for radioisotopic classification through radioactive emission.

O desenvolvimento de sistemas laser com pulsos ultracurtos trouxe a possibilidade de usinagem de estruturas muito pequenas em praticamente qualquer tipo de material. Neste trabalho foi dada continuidade a estudos já iniciados no Centro de Lasers e Aplicações (CLA) com os materiais dielétricos, introduzindo a largura temporal dos pulsos laser como mais uma variável e utilizando os conhecimentos adquiridos para a determinação de limiares de ablação e parâmetros de incubação em alguns metais como: aço AISI 1045, aço inoxidável VI138, cobre eletrolítico e molibdênio. A ausência de calor no processo de ablação dos metais torna-se muito difícil, pois a criação de uma camada de íons é muito prejudicada pela mobilidade eletrônica ao seu redor. Assim a ablação de metais com pulsos ultracurtos, tem como principal mecanismo a explosão de fase associada a outros processos que também contribuem na ablação, porém em menor escala, como a explosão coulombiana e a fusão ultrarrápida. Além disso, propriedades como a constante de acoplamento elétron-fônon e a condutividade térmica assumem um papel importante e devem ser levadas em conta na investigação do processo de ablação dos metais. Este trabalho possibilitou a obtenção de parâmetros de operação nos quais o calor transferido para a rede é minimizado, possibilitando a microusinagem de precisão e alterações controladas na morfologia da superfície de diversos metais. Os resultados propiciaram assim condições para novos desenvolvimentos e aplicações práticas de usinagem com pulsos ultracurtos. / The development of laser systems with ultrashort pulses brought the possibility of machining very small structures in virtually any type of material. In this work was continued the studies already started in Lasers and Applications Center (CLA), with dielectric materials, introducing temporal width of the laser pulses as another variable, and using the knowledge acquired to determine ablation threshold and incubation parameters of some metals such as AISI 1045 steel, VI 138 stainless steel, electrolytic copper and molybdenum. The absence of heat in the ablation process of metals is much more difficult since the creation of a layer of ions is greatly impaired by electronic mobility in its vicinity. Hence, the ablation process for metals with ultrashort pulses, has, as main mechanism, the phase explosion associated with other processes that also contribute in the process, but on a smaller scale, such as Coulomb explosion and ultrafast fusion. Moreover, properties such as electron-phonon coupling constant and thermal conductivity play an important role and should be taken into account in investigating the process of ablation of metals. This study made it possible to obtain operation parameter where the heat transferred to the lattice is minimized, enabling precision micromachining and controlled changes in the morphology of the surface of metals. The results provided conditions for new developments and real machining applications with ultrashort pulses.

The Fäboliden gold deposit is an ore body in northern Sweden’s Bothnian Basin and has been the subject of studies and test mining since the early 2000s when the Gold Line, an area of anomalously high-Au glacial till in Northern Sweden, became a center of economic interest. The deposit is a hypozonal orogenic gold deposit that displays many characteristic features of ore bodies of this type, including the presence of compound sulfide grains composed of a core of löllingite surrounded by a rim of arsenopyrite, and an abundance of pyrrhotite throughout the deposit and surrounding alteration zone. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to first map the distribution of trace elements in several of the arsenpyrite-löllingite grains, then to perform spot analyses of pyrrhotite grains in samples from across the distal and proximal alteration zones of the deposit. The maps of the trace elements in the compound löllingite-arsenopyrite grains show that: As and Au are found in greater abundance in the löllingite than in the arsenopyrite; Cu, Fe, S, and Ti are found in greater abundance in the arsenopyrite than in the löllingite; and Ag, Au, Bi, La, Mn, Pb, Sr, Ti and Tl are found in zones of secondary enrichment along fractures within the grains. Uranium and V may also be enriched along fractures, although this isn’t clear on all of the maps. Gold is an element of particular interest, because its distribution throughout the sulfide phases can be used to constrain the mechanism and relative timing of mineralization within the deposit. The presence of invisible gold within the löllingite, but not within the arsenopyrite, shows that gold is not incorporated into arsenopyrite at high temperatures and will instead be concentrated in the löllingite core of the composite grain and at the margin between the two sulfide phases as the löllingite is altered to arsenopyrite. Previous research on the Fäboliden gold deposit, including geothermometric analysis of vein-hosted graphite within fluid inclusions and garnet-biotite geothermometry as well as structural evidence provided by regional deformation, indicate that mineralization occurred post-peak metamorphism. The textures seen are therefore not conclusive of mineralization occurring syn- or pre-peak metamorphism, as has previously been proposed based on research of orogenic gold deposits in Western Australia. The spot analysis of pyrrhotite samples from across the deposit shows a distinct decrease in Ni and Co content in the proximal alteration zone, suggesting uptake of these elements by other minerals such as the löllingite and arsenopyrite. Multiple analyses performed on single grains show local variation, but are insufficient to establish the presence or determine the character of growth zonation within pyrrhotite.

The dissertation is split into two parts. The first part will be focused on changes in material properties found at the nanoscale, as miscibility and electronic structure can change significantly with size. The formation of classically-immiscible bimetallic nanoparticles (BNPs) becomes favorable at the nanoscale and novel catalytic properties can emerge from the bimetallic alloying. The formation of alloyed and non-alloyed BNPs is achieved through pulse laser ablation (PLA) and a significant increase in catalytic activity is observed for both. Recently discovered, the increased activity in the non-alloyed BNPs, deemed multicomponent photocatalysis, is examined and the proposed mechanism discussed. The second part of the talk will focus on thermal barrier coatings (TBCs), which are advanced, multi-layered coatings used to protect materials in high temperature environments. MCrAlY (M=Ni, Co) bond coats deposited via atmospheric plasma spray (APS) are intrinsically rough and initially the roughness provides a high surface area platform for the mechanical interlocking of the yttria stabilized zirconia (YSZ) top coat, which provides the bulk of the thermal insulation. After high temperature exposure, a protective oxide scale forms at the top coat/bond coat interface however the convex asperities of the bond coat can grow non-α-Al2O3 type oxides that can be detrimental for coating lifetime. A surface modification technique that removes the asperities while leaving intact the concavities is used to examine the role that roughness distribution has on 1100°C APS coating lifetime. Lastly, recent work validating a modelling strategy for evaluating 900°C TBC lifetimes, which can typically surpass 25 kh, is presented. Differences in coating-substrate interdiffusion behavior over 5-20 kh of 900°C exposure are discussed and reproduced with Thermo- Calc/DICTRA for three superalloys (1483, 247, X4) deposited with high velocity oxy fuel (HVOF) NiCoCrAlY coatings.

Modern observations of planktic foraminifera from sediment trap studies help to constrain the regional ecology of paleoceanographically valuable species. Results from a weekly-resolved sediment trap time series (2008–2014) in the northern Gulf of Mexico demonstrate that 92% of Globorotalia truncatulinoides flux occurs in winter (January, February, and March), and that encrusted and non-encrusted individuals represent calcification in distinct depth habitats. We use individual foraminiferal analysis (IFA) of G. truncatulinoides tests to investigate differences in the elemental (Mg/Ca) and isotopic composition (18O and 13C) of the encrusted and non-encrusted ontogenetic forms of G. truncatulinoides, and to estimate their calcification depth in the northern Gulf of Mexico. We estimate that non-encrusted and encrusted G. truncatulinoides have mean calcification depths of 66 ± 9 meters and 379 ± 76 meters, respectively. We validate the Mg/Ca-calcification temperature relationship for G. truncatulinoides and demonstrate that the 18O and Mg/Ca of the non-encrusted form is a suitable proxy for winter surface mixed layer conditions in the Gulf of Mexico. Care should be taken not to combine encrusted and non-encrusted individuals of G. truncatulinoides for down core paleoceanographic studies.

Bio-microdevices are miniaturised devices based on biologically derived components (e.g., DNA, proteins, and cells) combined or integrated with microfabricated substrates. These devices are of interest for numerous applications, ranging from drug discovery, to environmental monitoring, to tissue engineering. Before a bio-microdevice can be fully developed, specific fabrication issues need to be addressed. One of the most important is the spatial immobilization of selected biomolecules in specific micro-areas of the device. Among the biomolecules of interest, the controlled immobilization of proteins to surfaces is particularly challenging due to the complexity of these macromolecules and their tendency to lose bioactivity during the immobilization step. The present Thesis reports on three novel micropatterning techniques for the spatial immobilization of proteins with bioactivity retention and improved read-out of the resulting micropatterns. The technologies developed are based on three different micropatterning approaches, namely 1) direct-writing UV laser microablation (proLAB), 2) a novel microcontact printing method (�CPTA) and 3) a replica molding method combined with bead selfassembly (BeadMicroArray). The first two technologies, proLAB and �CPTA, are an implementation of existing techniques (laser ablation and �CP, respectively), whereas the third, i.e., the BeadMicroArray, is a totally new technique and type of patterning platform. 'ProLAB' is a technology that uses a micro-dissection tool equipped with a UV laser (the LaserScissors�) for ablating a substrate made of a layer of ablatable material, gold, deposited over a thin polymer layer. The latter layer is transparent to the laser but favours protein adsorption. In the present work microchannels were chosen as the structure of interest with the aim of arranging them in 'bar-codes', so to create an 'information-addressable' microarray. This platform was fabricated and its application to specific antigen binding demonstrated. The second technique that was developed is a microstamping method which exploits the instability of a high-aspect ratio rubber stamp fabricated via soft-lithography. The technique is denominated microcontact printing trapping air (�CPTA) since the collapsing of a rubber stamp made of an array of micro-pillars over a plane glass surface resulted in the formation of a large air gap around the entire array. The method can be successfully employed for printing micro-arrays of proteins, maintaining biological activity. The technique was compared with robotic spotting and found that microarrays obtained with the �CPTA method were more homogeneous and had a higher signal-tonoise ratio. The third technique developed, the BeadMicroArray, introduces a totally new platform for the spatial addressable immobilization of proteins. It combines replica molding with microbead self-assembling, resulting in a platform where diagnostic beads are entrapped at the tip of micropillars arranged in a microarray format. The fabrication of the BeadMicroArray involves depositing functional microbeads in an array of V-shaped wells using spin coating. The deposition is totally random, and conditions were optimised to fill about half the array during spin coating. After replica molding, the resulting polymer mold contains pyramid-shaped posts with beads entrapped at the very tip of the post. Thanks to the fabrication mode involved, every BeadMicroArray fabricated contains a unique geometric code, therefore assigning a specific code to each microarray. In the present work it was demonstrated that the functionality of the beads after replica molding remains intact, and that proteins can be selectively immobilized on the beads, for instance via biorecognition. The platform showed a remarkable level of selectively which, together with an efficient blocking towards protein non-specific adsorption, lead to a read-out characterized by a very good signal-to-noise. Also, after recognition, a code was clearly visible, therefore showing the encoding capacity of this unique microarray.

In the first part of this thesis, CaCO3 (calcite) powder ball-milled to micro/nano scale were subjected to isothermal firing in the temperature range of 450-600 ¢XC in an open air furnace in order to study specific-surface area reduction as a result of early-stage sintering/coarsening/coalescence/repacking (denoted as SCCR process) of the fine particles. The surface area and pore size distributions were obtained from the BET and BJH methods, respectively. The H1 type adsorption/desorption hysteresis loop of the type IV isotherm was used as an indicator of cylindrical pore formation upon dry pressing and firing of the powder. The apparent activation energy for the onset SCCR of the dry-pressed calcite powder turned out to be 57.5¡Ó1.0 kJ/mol based on t0.5, i.e. time for 50 % specific surface area reduction. The minimum temperature for such an incipient SCCR process was estimated to be 590K (317¢J) by extrapolating the specific-surface-area reduction rate to null. The mechanism of specific surface area change includes the Brownian motion, coarsening and coalescence/repacking of calcite particles besides sintering via synchronizing diffusion of calcium ion and carbonic acid ion along grain surface and boundary. In the second part of this thesis, pulsed laser ablation on micrometer-sized calcite (type I) powder in liquid H2O (PLAL) was conducted to study the structure and optical property change of calcium carbonate under a dynamic high-temperature. high-pressure aqueous condition. X-ray diffraction (XRD) indicated the fragmented calcite I powder via such a PLAL process change predominantly into a metastable CaCO3 II phase presumably by a displacive type transformation from calcite I and/or nucleated from atom clusters. The refined XRD lattice parameters indicate a significant internal compressive stress (up to 1.5 GPa) was retained for the predominant CaCO3 II nanoparticles having well-developed (013), (010) and (013) faces as revealed by transmission electron microscopy (TEM). Minor calcium carbonate nanoparticles were also identified by TEM to be other high-pressure polymorphs (type III and aragonite), hydrated (monohydrocalcite, ikaite), amorphized (amorphous calcium carbonate), and even decomposed as cubic lime (CaO). Monohydrocalcite occasionally occurred as epitaxial intergrowths within the predominant CaCO3 II matrix. Vibrational spectroscopy (Raman and FTIR) indicated the structure units of the overall nanoparticles by the PLAL process were considerably modified as a combined results of size miniature, protonation and internal compressive stress. The UV-visible absorption results further indicate that the minimum band gap of the colloidal solution was narrowed down to ca. 5 eV and 3 eV for the predominant CaCO3 II and minor accessory phases, respectively, thus shedding light on their potential opto-catalytic applications.

This thesis is about the kinetics of anisotropic acidic/hydrothermal dissolution of apatite bulk single crystal vs. nanorods, and the kinetic phase change of dense nanocondensates of SnO2 vs. Ni-dissolved SnO2 prepared by laser ablation condensation technique. In the first regard, directional dissolution of a natural (OH,F,Cl)-bearing apatite has been studied at various solution pH values (0~3) and 30 oC. This apatite showed abnormally high O-H stretching frequencies due to the substitution of Cl for OH. The advance of dissolution front indicated that steady-state directional dissolution for pH = 0-2 followed an apparent rate law of rate(mole / m2h)¡×kaH+n, where the rate constants (k) are 2.15 and 1.61; and the rate orders (n) are 1.44 and 1.30 for [0001] and <11 0> directions, respectively. Previous study, however, indicated a smaller n value (n = 0.55~0.70) for fluorapatite powders at higher pHs. A nonlinear pH dependence of logarithmic dissolution rate at a wide pH range implied that the surface active sites and/or rate-determining steps have changed when the acidity of solution and/or the composition of the apatite were changed. The opening of etch pits on basal planes further indicated that the dissolution rates along the three principal directions have the following relationship: [0001] > <11-20> > <10-10> for pH=0-1, but the order was reversed for pH > 3. As a comparison, static immersion of needle-like hydroxyapatite nanoparticles in neutral hydrothermal solution at 100oC caused preferential dissolution along the crystallographic c-axis to form nanorods with a lower aspect ratio. The anisotropic dissolution behavior is due to diffusion-controlled rapid dissolution at the sharp tip, and interface-controlled dissolution at side surfaces in terms of active sites. Extensive dissolution was accompanied with amorphization via explosive generation of dislocations, forming corrugated surface with both negative and positive curvature regions. The amorphous residue was significantly Ca and OH depleted when treated in the hydrothermal solution at pH=3. The BET specific surface area of the apatite nanoparticles remained 45¡Ó1 m2/g after immersion in neutral solution at 100oC for 36 h, but drastically decreased to 24.5 m2/g in acidic (pH =3) solution at 100oC for 8 h due to coalescence of the partially amorphized apatite powders. The specific surface area and average pore size also remained nearly unchanged for the dry pressed powders subject to firing at 100oC, but decreased and increased, respectively when sintered shortly at 600oC in air. BJH measurements at 77 K indicated the N2 adsorption/desorption hysteresis loops shift toward high relative pressure for sintered/hydrothermally etched powders indicating a higher activation energy of forming overlain liquid-like nitrogen layers. This can be attributed to a lower surface energy of the powders due to their shape change and/or partial amorphization. Alternatively, desorption through cavitation via the small voids could occur, in particular for such treated samples with characteristic bimodal pore size distribution. In the second subject, dense SnO2 with fluorite-type related structures were synthesized via very energetic Nd-YAG laser pulse irradiation of oxygen-purged Sn target. Combined effects of rapid heating to very high temperatures, nanophase effect, and dense surfaces account for the condensation of fluorite-type structure which transformed martensitically to baddeleyite-type accompanied with twinning, commensurate shearing and shape change. Alternatively Pa-3-modified fluorite-type hardly survived transformation to a-PbO2 type and rutile type in the dynamic process analogous to the case of static decompression. In addition, the rutile-type SnO2 nanocondensates have {110}, {100} and {101} facets, which are beneficial for {~hkl} vicinal attachment to form edge dislocations, faults and twinned bicrystals. The {011}-interface relaxation, by shearing along <011> directions, accounts for a rather high density of edge dislocations near the twin boundary thus formed. The rutile-type SnO2 could be alternatively transformed from orthorhombic CaCl2-type structure (denoted as o) following parallel crystallographic relationship, (0 1)r//(0 1)o; [111]r//[111]o, and full of commensurate superstructures and twins parallel to (011) of both phases. Furthermore, SnO2-NiO solid solution (ss) condensates were fabricated by laser ablation on Ni-Sn target at 1.1 J/pulse and oxygen flow of 50 L/min. AEM observations indicated that the particles were more or less coalesced/agglomerated as nano chain aggregate or in close packed manner. The Ni-rich condensates have rock salt structure with defect clusters not in paracrystalline distribution as would otherwise develop into the spinel phase. The Sn-rich condensates are predominantly rutile-type with minor baddeleyite-type, which are vulnerable to martensitic transformation/relaxation to form {101} incommensuare faults as well as epitaxial twin variants of rutile upon rapid cooling and/or electron irradiation. Islands of metallic Ni-Sn-NiSn were partially oxidized/solidified when deposited on silica glass.

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Wurtzite (W)-type ZnO condensates showed preferred orientation {10 1} when deposited on glass substrate by pulsed laser ablation on Zn target in the presence of oxygen. Such an artificial epitaxy depends on the well developed {10 1} surfaces of the condensates, which enabled {10 1}-specific coalescence to form twin and single crystal regardless of the co-deposited Zn. The W-ZnO condensates have decreasing particle size with increasing oxygen flow rate and a considerable residual stress due to the combined effects of rapid heating/cooling and thermal/lattice mismatch with Zn following parallel epitaxy or (01 )W-ZnO//(01 0)Zn; [ 2 3]W-ZnO//[0001]Zn involving {10 1} slip (Part I). In addition, wurtzite (W)-type ZnO/Zn composite deposit with preferred orientation {10 1}W-ZnO and (0001)Zn respectively on glass substrate in chapter I under Isothermal (600oC) atmospheric annealing caused self-catalyzed vapor-liquid-solid growth of rod-like W-ZnO whiskers with unusual habit. Analytical electron microscopic observations indicated that the W-ZnO whiskers extend along the zone axis of the well-developed polar surfaces {10 1} for a beneficial lower electrostatic energy and surface energy. Alternatively, the whiskers extend via {11 1}-specific growth twinning and/or coalescence twinning for a beneficial fair coincidence-site lattice at the twin boundary (Part II). Furthermore, Zn particulates overlain with wurtzite (W)-type ZnO condensates having nearly orthogonal {10 1} and {11 1} facets were found to self-catalyze unusual tapered W-ZnO whiskers upon isothermal atmospheric annealing, i.e. thermal oxidation, at 600oC. Analytical electron microscopic observations indicated that such whiskers formed tapered slabs having mosaic {10 1} and {2 1} twinned domains. The tapered whiskers can be rationalized by unconventional vapor-liquid-solid growth, i.e. {hkil}-specific coalescence twinning growth from the ZnO condensates taking advantage of a partially molten bottom source of Zn and the adsorption of atoms at the whisker tips and steps under the influence of capillarity effect (Part III). Finally, Electron irradiation of nano-size wurtzite (W)-type ZnO condensates with intimate mixture of parallel epitaxial Zn caused {10 1}W slip to form a single domain of rock salt (R)-type core and W-type shell. The two polymorphs follow (1 1)R//(0 11)W; [011]R//[ 2 3]W, i.e. chair type Peierls distortion with additional 38 degree tilting (001)R along the ( 2 0)W plane for a fair match of (10 1)W/(1 1)R, the same as one of the two paths for the back-transformation of R-ZnO into a lower crystal symmetry. The martensitic nucleation of R-type ZnO can be attributed to dynamic migration of interstitials/vacancies, lattice mismatch stress, and capillarity effect.