Made available in DSpace on 2017-07-10T17:37:19Z (GMT). No. of bitstreams: 1 Gisele Cristina Justen.pdf: 463949 bytes, checksum: 3f4887ae9ce1687587ebb55d5c0306c6 (MD5) Previous issue date: 2007-08-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was to compare the chemical composition of the soy in conversion for organic agriculture - 1° year in conversion (C1), 2° year in conversion (C2) and 3° year in organic conversion or (C3) - being known the data meteorological of the culture place. To cultivate used it was the CD-216, proceeding from harvest 2005/2006, the City of Santa Helena/PR. The studied variables had been the text of humidity and the centesimal composition (protein, oil, ashes and carbohydrates), the mineral text (P, K, Ca, Mg, Zn, Cu, Fe and Mn) and the text of isoflavones of the grains. Considering the three years in conversion, some factors had differed significantly. The text of humidity in C1 (8,43 %) differed significantly from C2 (9,04 %). For leached ashes and oil texts significant difference between the three years was observed. The raised texts more of oil (21,1 %) and leached ashes (4,79%) had been found in C3. It did not have significant differences between the treatments for the text of protein and carbohydrates, however the biggest texts had been found in C1. In relation to minerals, the studied components had occurred significant differences between all, to the exception of the N. The concentrations of P, K and Cu had been significantly bigger in C1. The concentrations of Mg in C1 and C2 had been similar, differing significantly in C3. The concentrations of Ca, Zn and Mn had been significantly bigger in C3. The concentration of Fe was significantly bigger in C2. The text of total isoflavones differed significantly between C1, C2 and C3, being superior in C3. Isoflavones Daidzina, Genistina and Malonil-Genistina had demonstrated significant differences between the years in conversion. These isoflavones had also presented greaters texts in C3. Isoflavones Malonil-Daidzina, Daidzeína, Genisteína had also presented expressives values in C3, however they had not differed significantly / O objetivo deste trabalho foi comparar a composição química da soja em conversão para agricultura orgânica - 1° ano em conversão (C1), 2° ano em conversão (C2) e 3° ano em conversão ou orgânica (C3) conhecendo os dados meteorológicos do local de cultivo. A cultivar utilizada foi a CD-216, proveniente da safra 2005/2006, do Município de Santa Helena/PR. As variáveis estudadas foram o teor de umidade, a composição centesimal (proteína, óleo, cinzas e carboidratos), o teor de minerais (P, K, Ca, Mg, Zn, Cu, Fe e Mn) e o teor de isoflavonas dos grãos. Considerando os três anos em conversão, alguns fatores diferiram significativamente. O teor de umidade em C1 (8,43 %) diferiu significativamente de C2 (9,04 %). Para os teores de óleo e de cinzas observou-se diferença significativa entre os três anos. Os teores mais elevados de óleo (21,1%) e de cinzas (4,79%) foram encontrados em C3. Não houve diferenças significativas entre os tratamentos para o teor de proteína e de carboidratos, porém os maiores teores foram encontrados em C1. Em relação aos minerais, ocorreram diferenças significativas entre todos os componentes estudados, à exceção do N. As concentrações de P, K e Cu foram significativamente maiores em C1. As concentrações de Mg em C1 e C2 foram semelhantes, diferindo significativamente em C3. As concentrações de Ca, Zn e Mn foram significativamente maiores em C3. A concentração de Fe foi significativamente maior em C2. O teor de isoflavonas totais diferiu significativamente entre C1, C2 e C3, sendo superior em C3. As isoflavonas Daidzina, Genistina e Malonil-Genistina demonstraram diferenças significativas entre os anos em conversão. Essas isoflavonas também apresentaram maiores teores em C3. As isoflavonas Malonil-Daidzina, Daidzeína, Genisteína também apresentaram valores mais expressivos em C3, porém não diferiram significativamente

Xiao, Manda = 金納米晶修飾的空心介孔二氧化矽微球在表面等離子體激元調製下的光散射行為 / 肖蔓達. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / Abstracts in English and Chinese. / Xiao, Manda = Jin na mi jing xiu shi de kong xin jie kong er yang hua xi wei qiu zai biao mian deng li zi ti ji yuan diao zhi xia de guang san she xing wei / Xiao Manda. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgement --- p.iv / Table of Contents --- p.vi / List of Figures --- p.viii / List of Tables --- p.x / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Plasmonic Properties of Noble Metal Nanocrystals --- p.1 / Chapter 1.2 --- Light Scattering from Dielectric Spheres --- p.6 / Chapter 1.3 --- Motivations and Outline of the Thesis --- p.9 / Chapter 2 --- Characterization Techniques --- p.17 / Chapter 2.1 --- Instrumentation --- p.17 / Chapter 2.2 --- Extinction Measurement of Au Nanocrystals and the HMSMSs Decorated with the Au Nanocrystals --- p.17 / Chapter 2.3 --- Sample Preparation for the TEM and SEM Characterization --- p.18 / Chapter 2.4 --- Dark-Field Imaging and Spectroscopy of the Individual Microspheres --- p.19 / Chapter 3 --- Fabrication of Hollow Mesoporous Silica Microspheres Decorated with the Au Nanocrystals --- p.25 / Chapter 3.1 --- Preparation of the Hollow Mesoporous Silica Microspheres --- p.25 / Chapter 3.2 --- Growth of the Au Nanocrystals --- p.29 / Chapter 3.3 --- Assembly of the Au Nanocrystals onto the Hollow Mesoporous Silica Microspheres --- p.32 / Chapter 4 --- Resonant Scattering Properties of the Hollow Mesoporous Silica Microspheres --- p.38 / Chapter 4.1 --- Experimental Results --- p.38 / Chapter 4.2 --- Calculation of the Scattering Spectra by Mie Theory --- p.42 / Chapter 4.3 --- Summary --- p.46 / Chapter 5 --- Resonant Scattering Properties of the Au Nanocrystal-Decorated Hollow Mesoporous Silica Microspheres --- p.49 / Chapter 5.1 --- Effect of the Plasmon Resonances of the Au Nanocrystals on the Resonant Scattering Behaviors of the HMSMSs --- p.49 / Chapter 5.2 --- Estimation of the Scattering Enhancement Factors --- p.54 / Chapter 5.3 --- Summary --- p.59 / Chapter 6 --- Summary --- p.61

Diante da importância do zinco no desempenho produtivo e reprodutivo de matrizes suínas, e no desempenho de leitões, foram conduzidos três experimentos com o objetivo de avaliar diferentes fontes de zinco na alimentação de suínos. O experimento I avaliou diferentes fontes de zinco, orgânico (zinco+metionina ((Zn-Met) e zinco+glicina(Zn-Gli)) e inorgânico (óxido de zinco(ZnO)) na dieta de matrizes em gestação e lactação e os efeitos do uso destas fontes na sua progênie. Foram utilizadas 18 fêmeas de uma linhagem comercial distribuídas em delineamento experimental de blocos ao acaso, com três tratamentos e seis repetições de um animal. As características avaliadas nas matrizes foram: peso, espessura de toucinho, prolificidade, número de leitões nascidos vivos e níveis séricos de zinco no colostro e no leite. Para os leitões após parto até a desmama foram analisados: níveis de zinco no soro, ganho de peso, histomorfologia entérica e densidade óssea. No experimento II foram utilizados 180 leitões, desmamados com 21 dias de idade, distribuídos em delineamento de blocos ao acaso em esquema fatorial 3 x 3 (3 dietas maternas - 100 ppm de ZnO, Zn-Met, Zn-Gli x 3 dietas da progênie - 100 ppm de ZnO, Zn-Met, Zn-Gli) totalizando 9 tratamentos e 5 repetições de 4 animais cada, em que foram avaliados o desempenho, incidência de diarréia, níveis de zinco no soro, densidade óssea e histomorfologia entérica No experimento III foram utilizados 810 leitões, desmamados com 21 dias de idade, distribuídos em delineamento de blocos ao acaso com 6 tratamentos de 3 repetições de 45 animais: Fases I e II - 1. dieta + 2300 ppm de ZnO; 2. dieta + 2200 ppm de ZnO + 100 ppm de Zn-Met; 3. dieta + 2200 ppm de ZnO + 100 ppm de Zn-Gli; 4. dieta + 2400 ppm de ZnO; 5. dieta + 2200 ppm de ZnO + 200 ppm de Zn-Met; 6. dieta + 2200 ppm de ZnO+200 ppm de Zn-Gli; Fase III - 1. dieta + 1600 ppm de ZnO; 2. dieta + 1500 ppm de ZnO + 100 ppm de Zn-Met; 3. dieta + 1500 ppm de ZnO + 100 ppm de Zn-Gli; 4. dieta + 1700 ppm de ZnO; 5. dieta + 1500 ppm de ZnO + 200 ppm de Zn-Met; 6. dieta + 2200 ppm de ZnO+200 ppm de Zn-Gli, em que avaliou-se o desempenho dos animais. Os dados foram analisados utilizando o programa SAS (1998). As médias dos tratamentos foram comparadas pelo teste de Tukey ao nível de 5% de probabilidade, segundo Steel e Torrie (1980). / Given the importance of zinc in the productive and reproductive performance of sows and piglets performance, three experiments to evaluate different sources of zinc in swine were conducted. The first experiment evaluated different sources of zinc, organic (zinc methionine (Zn-Met) and zinc glycine (Zn-Gly)) and inorganic (zinc oxide (ZnO)) in the diet of pregnant gilts and sows lactating and the effects of using these sources in their progeny. Were used 18 female of a commercial strain distributed in experimental design of randomized blocks with three treatments and six repetitions with one animal each. The characteristics evaluated in the sows were: weight, backfat thickness, prolificacy, number of piglets born alive and zinc levels in serum, colostrum and milk; In the piglets after birth until weaning were analyzed: serum levels of zinc, weight gain, bone density and histomorphology enteric. The second experiment 180 piglets were used, weaned at 21 days of age in a randomized block design in a factorial 3 x 3 (3 maternal diets - 100 ppm from ZnO , Zn-Met , Zn-Gly x 3 diets progeny - 100 ppm ZnO , Zn-Met - , Zn-Gly) totaling 9 treatments and 4 replicates of 5 animals each, which evaluated the performance, diarrhea incidence, serum zinc levels, bone density and histomorphology enteric. The third experiment 810 weaned pigs weaned at 21 days of age in a randomized block design with 6 treatments of 3 replicates of 45 animals each: Phases I and II - 1. diet + 2300 ppm of ZnO; 2. diet + 2200 ppm of ZnO + 100 ppm of Zn-Met; 3. diet + 2200 ppm ZnO + 100 ppm of Zn-Gly; 4. diet + 2400 ppm of ZnO; 5. diet + 2200 ppm of ZnO + 200 ppm of Zn- Met; 6. diet + 2200 ppm of ZnO + 200 ppm of Zn-Gly; Phase III - 1. diet + 1600 ppm of ZnO; 2. diet + 1500 ppm of ZnO + 100 ppm of Zn-Met; 3. diet + 1500 ppm of ZnO + 100 ppm of Zn-Gly; 4. diet + 1700 ppm of ZnO; 5. diet + 1500 ppm of ZnO + 200 ppm of Zn- Met; 6. diet + 2200 ppm of ZnO + 200 ppm of Zn-Gly in evaluating the performance of animals. All datas were analyzed using SAS (1998 ) program. The treatment means were compared by Tukey test at 5 % probability , according to Steel and Torrie (1980).

Este trabalho enfocou o levantamento de informações químicas e mineralógicas de detalhe em amostras de depósitos alcalinos e alcalino carbonatíticos brasileiros contento terras raras, de modo a fornecer subsídios para o desenvolvimento de processos de aproveitamento. Estes depósitos apresentam elevados volumes de recursos, baixos teores de elementos de terras raras (essencialmente terras raras leves) e elevada complexidade mineralógica. As amostras estudadas são provenientes de depósitos lateríticos, com teor total de óxidos de terras raras entre 1,27 e 6,45%, sendo a monazita o principal mineral portador desses elementos, exceto em uma das amostras, onde é predominante a bastnaesita; como minerais traços estão presentes cerianita, xenotima e um fosfato de escândio. Os minerais de terras raras tendem a concentrar-se em direção às frações granulométricas mais finas, mostram d50 de 15 µm nas frações acima de 0,008 mm e chegam a valores inferiores a 0,1 µm abaixo da mesma. Esses minerais ocorrem preferencialmente em íntimas associações com a ganga, sendo que valores superiores a 60% de liberação (em área) são observados apenas nas frações menores que 0,020 mm. O potencial de concentração desses minerais foi avaliado por separações físicas e extração hidrometalúrgica. Separações físicas em líquidos densos e magnéticas não possibilitaram a obtenção de produtos enriquecidos em terras raras. O resultado mais promissor refere-se à possibilidade de remoção de um produto contaminante magnético nas frações retidas em 0,020 mm e que responde por 30% do total de Fe2O3 contido nas amostras (em média), sem perdas significativas das terras raras. A condição experimental otimizada para a dissolução seletiva dos minerais de terras raras em meio ácido foi estabelecida a partir de um planejamento experimental baseado em princípios estatísticos. Para o material cominuído abaixo de 0,30 mm, a solubilização dos óxidos de terra raras é de 77%, considerando-se ácido sulfúrico concentrado, reduzida porcentagem de sólidos, temperatura ambiente e tempo de 4 horas. Maiores níveis de solubilização das terras raras podem ser alcançados, mas juntamente com elevação da solubilização da ganga. / This work focused on the acquisition of chemical and mineralogical detailed information in samples from Brazilian alkaline and alkaline-carbonatitic deposits containing rare earths, in order to provide subsidies for process development. These deposits present high volumes of resources, low contents of rare earth elements (essentially light rare earths) and high mineralogical complexity. The studied samples are lateritic materials, with a total content of rare earth oxides between 1.27 and 6.45%, being monazite the main rare earth bearing mineral, except in one of the samples, where bastnaesite is predominant; cerianite, xenotime and a scandium-phosphate occur as trace. Rare earth minerals tend to enrich toward the finest sieve fractions with an medium grain size of 15 µm in the fractions greater than 0.008 mm and decreasing below 0.1 µm in finer fractions. These minerals occur preferentially in intimate associations with the gangue; liberation greater than 60% (in area) are observed under 0.020 mm fractions. The concentration potential of these minerals was evaluated through physical separation and hydrometallurgical extraction. Physical separations (heavy liquid and magnetic) did not succeed in obtaining products enriched in rare earths. The most promising result were the possibility of removing magnetic phases above 0.020 mm (responsible for 30%, on average, of the total Fe2O3 contained in the samples) without significant losses of rare earths. The rare earths acid leaching protocols and conditions were established by statistical experimental design. For samples comminuted below 0.30 mm, the best rare earths solubilization (77%) and with minimum gangue leaching was obtained in concentrate sulfuric acid, low solids concentration, environmental temperature and four hours of reaction. Higher levels of rare earths solubilization can be achieved, however accompanied by higher gangue solubilization.

Geochemical, mineralogical and tenor variation studies were carried out on the cores from UMT040, UMT064 and UMT063, located in the Flatreef on Turfspruit, in the southern sector of the Platreef. The investigation comprised three objectives (1) to identify controls on mineralisation in the upper section of the Platreef, (2) to construct a 3D PGE tenor model, and (3) to test whether the new geological interpretation on Turfspruit correlates with the eastern and western limbs of the Bushveld Complex. The above-mentioned holes were used for geochemical analyses of major and trace elements; and UMT064 was also used for orthopyroxene microprobe analyses. For construction of the tenor model, a total of 276 drill holes were used. The distance between drill holes for geochemical studies is 145 m and 175 m respectively; and for the tenor model is approximately 100 m. The outcomes of the study have demonstrated that the upper section of the Platreef comprise at least four lithological units i.e. the topmost portion of T1, lowermost portion of T1, T2 Upper and T2 Lower that can be interpreted to have been formed by four separate pulses of magma. Considering the possibility of the T2 Lower being metamorphosed calc-silicates, this reduces the number of magma pulses to three. This is supported by the mineralogy, geochemical content and tenor variations. The T1 is made up of an orthopyroxenite (feldspathic in places), the T2 Upper comprised a pegmatoidal orthopyroxenite (also feldspathic in places) and the T2 Lower is made up of a harzburgite. High grade PGE, Ni and Cu mineralisation was found to occur within two zones in the upper section of the Platreef i.e. the T1m and T2 (Upper and Lower). Mineralisation occurs in the form of base metal sulphides such as pyrrhotite, pentlandite and chalcopyrite; and PGEs are dominated by amphoterics (PGE-arsenides, tellurides, antimonides and bismuthinides). These amphoterics are associated with base metal sulphides. The sulphides in both the T1m and T2 are interstitial. PGE minerals such as michenerite, sperrylite, hollingworthite and cooperite are present in the study area. In the T2, an increase in sulphide content and PGE grades are generally associated with the presence of the “main” chromitite stringer/ seam at the contact between a feldspathic pyroxenite (T1) and the coarse-grained to pegmatoidal pyroxenite (T2 Upper). Several other chromitites might be present above and below this contact, and it has been noted that not all of those chromitites are associated with an increase in sulphide content and higher PGE grades. PGE grades were found to be higher in T2 Upper than in T2 Lower, whereas, the base metals (particularly Ni) are generally higher in T2 Lower. In the T1m, mineralisation occurs close to the contact between the feldspathic pyroxenite and orthopyroxenite, but only the orthopyroxenite hosts the sulphides. Chromitite stringers rarely occur in the T1m. Where present, they generally occur at the top of the mineralised zone. The sulphides in both the T1m and T2 are thought to have resulted from separate and different processes. Those in the T1m are thought to have resulted from a fractional segregation process, whereas the sulphides in the T2 were thought to have been emplaced in bulk or as a mush. The 3D PGE tenor model has demonstrated that the tenor in both the T1 and T2 are higher than previously thought for the northern limb of the Bushveld Complex. Tenors in the T1 reach up to 700 ppm, whereas tenors of about 1000 ppm were recorded in the T2. These tenors are comparable to the tenors measured from the sulphide melt inclusions elsewhere in the northern limb. Tenors are the highest in the northwestern part of Turfspruit and they gradually decrease towards the southeast. Both the T1 and T2 are dominated by a tenor of about 100 ppm. In the T1, a tenor of 250 ppm is dominant in the northwestern and southeastern parts of the study area, whereas in the T2 it is only dominant in the northwestern part. Vertical variation in tenors has shown that the tenors are the highest in the topmost portion of the T1 and at the top of T2 Upper (below the T1-T2 contact). The T1 has been found to be comparable with the Merensky Reef due to the following: (a) similarities with respect to major and trace element compositions of whole rock analyses; (b) Cr/MgO ratios which are greater than 80; and (c) similarities in the pyroxene content excluding the MgO/((MgO)+FeO) ratio and CaO contents; and in the PGE tenor of the sulphides. In addition, the T1 has many of the characteristics of the model proposed by Naldrett et al (2009) for the formation of the Merensky Reef in the western Bushveld. However, the differences between the T1 and the Merensky Reef were also noted i.e. the MgO/((MgO)+FeO) ratios in this study are lower (averaging 0.71) than the Mg# reported for the Merensky Reef (Mg#78-83), the upper Critical Zone (Mg#78-84) and elsewhere in the Platreef north of Turfspruit. The CaO levels (representing the wollastonite component of the orthopyroxene) at Turfspruit are higher (>2 wt %) compared to the Merensky Cyclic Unit and other parts of the northern limb where the CaO levels are below 2 wt %. This is an indication that the pyroxene composition at Turfspruit is more evolved compared to the Merensky Reef.

The Coral Sea has been the host to a variety of large carbonate platforms over the geologic past and presently hosts the world's largest system of coral reefs, the Great Barrier Reef, stretching more then 2,300 km along Australia's northeast coast. The Marion Plateau, which today is the site of 400 m deep hemipelagic sediment drifts, once supported two large carbonate platforms that were precursors to reef growth on the central and southern Great Barrier Reef. Previous work examining the growth phases, drownings and rejuvenation of these platforms is extensive. The purpose of this research is to examine the factors controlling the earliest sedimentation on the margin and how it influenced early development of the carbonate platforms. One hundred and eighty-three samples were taken from the base of Hole 1195 B, that was drilled during the Ocean Drilling Program's Leg 194. Analyses were performed using x-ray diffraction on the bulk powder and decalcified less than 2um size fraction smear slides. Four distinct sedimentary facies were defined on the basis of mineralogy and constituent grains. The initial marine transgression of the Marion Plateau was not a straightforward one where a shallow-water margin gradually transitioned into a deep-water margin. Instead, sediments record a complex history of unconformities, hardgrounds, and discrete sedimentary units. The initial flooding was complex as a result of its initially shallow depth at a time characterized by several glacio-eustatic sea-level changes. The data indicate that eustasy has been the strongest control on sediment deposition and clay mineral patterns on the Plateau. Falling sea level resulted in periods of increased detrital input and limited soil formation. Also, a decreasing kaolinite trend in the early Miocene, during a rising sea level, indicates that clays forming on land as a result of climate were not transported out onto the plateau.

Opaque oxide minerals (ilmenite, chromite, and magnetite) in sands from the Oregon continental shelf have been studied to establish the provenance, dispersal, and grade of potential shelf placer deposits. The study area extends southward from offshore of the Columbia River in northern Oregon to the Klamath River in northern California.

Thesis (MSc. (Physics)) --University of Limpopo, 2009 / Calculations were carried out on transition-metal sulphides (TMS) and transitionmetal arsenides (TMA), in both pyrite- and marcasite-type structures, using planewave (PW) pseudopotential methods within density functional theory (DFT) in the local density approximation (LDA). The structural, electronic and optical properties for both pyrite- and marcasite-type structures (naturally occurring and converted) have been investigated. The equilibrium lattice parameters were investigated and are in good agreement with the experimental values. The heats of formation calculations predict that the naturally occurring pyrite- and marcasite-type structures are more stable than the converted ones. In particular, the calculated pyrite-type RuS2 compares well to the experimental value (with energy difference of 0.381 eV/atom). The bulk modulus and elastic properties were calculated. The predicted anisotropic ratio shows that the naturally occurring pyrite- and marcasite-type structures are more stable than the converted ones. Moreover, the electronic density of states and band structure calculations reveal that most compositions shows semiconducting behaviour except for the converted pyritetype structures, i.e OsAs2 and RuAs2 where a metallic behaviour was observed. The electronic charge density and charge density difference show charge accumulation on bonding atoms, predicting the charge gain/ loss and nature of bonding to be covalent/ weak ionic between the atoms. Lastly, optical properties are computed at equilibrium and predict that naturally occurring structures have lower absorption and reflectivity than the converted structures. At different pressures ranging from -10 GPa to 10 GPa, the absorption and reflectivity spectra show a shift from the 0 GPa spectrum for all the structures / National Research Foundation

Thesis (Ph.D (Physics)) --University of Limpopo, 2005 / We have derived a potential model for °uorapatite Ca10(PO4)6F2, ¯tted to structure, elastic constants and vibrational frequencies of the phosphate groups, which is compatible with existing calcite and °uorite potential mod- els. We then modelled the structure and stabilities of the dry and hydrated f0 0 0 1g, f1 0 1 0g, f1 0 1 1g, f1 1 2 0g, f1 0 1 3g and f1 1 2 1g surfaces, which calculations con¯rmed the experimental dominance of the f0 0 0 1g surface, which is prominently expressed in the calculated thermodynamic morphologies. The dehydrated morphology further shows the experimental f1 1 2 1g twinning plane, while the f1 0 1 0g cleavage plane is expressed in the hydrated morphology. Molecular adsorption of water has a stabilising e®ect on all six surfaces, where the surfaces generally show Langmuir be- haviour and the calculated hydration energies indicate physisorption (73 - 88 kJ mol¡1). The chains of °uoride ions surrounded by hexagonal calcium channels can become distorted in two major ways during relaxation: either by a shortening/lengthening of the FF distances, when the channel is perpendicular to the surface, or by distortion of the CaF bonds when the channel is parallel to the surface. Both distortions occur when the channel runs at an angle to the surface. Other relaxations include compression of the calcium sub-lattice and rotation of surface phosphate groups. We have modelled adsorption of a range of organic molecules onto dif- ferent °uorapatite surfaces, due to the importance of organic/ inorganic in- teractions in biological situations. We have selected organic molecules that represent a model for the carboxylic acids, alkyl hydroxamates and those 3 that contain both the aldehyde and hydroxyl functional groups. Adhesion of these organic molecules on the surfaces has shown strong interaction between the surface's Ca ions and the molecule's oxygens, more especially the car- bonyl oxygens than any other interactions. It was found that the number of interactions between the ions of adsorbate molecule and the mineral surfaces thus contribute signi¯cantly to the exothemicity of adsorption. Further more, simulations of apatite thin ¯lms at a range of ®-quartz surfaces have shown how the strength of adhesion between thin ¯lms of ap- atite material and ceramic silica surfaces is crucially dependent upon both the orientation of the ¯lm relative to the substrate and the nature of the silica surfaces, a ¯nding that is important in a wide number of applications, from basic geological research on intergrowth of phosphate and silicate rock minerals to the search for more e®ective surgical implant materials. It was shown that although the unrelaxed quartz surface is more reactive toward the apatite ¯lm, the more regular thin ¯lm structures grown at the pre-relaxed quartz surfaces lead to more stable interfaces. Film growth at the unrelaxed quartz surface is energetically increasingly unfavorable, whereas growth at the pre-relaxed surface is calculated to continue beyond the ¯rst layer, where the adhesion energy is convergent with the layer growth of the thin ¯lm. Ad- hesion of apatite thin ¯lm on hydroxylated surfaces of ®-quartz has shown to be energetically less favourable than at dry surfaces. This was because the thin ¯lm interact mainly with the hydroxyl ions on the surface of quartz. However, the adhesion energy is still convergent with layer growth of the thin ¯lm on the hydroxylated surfaces. / National Research Foundation of South Africa (NRF), Council for Scientific and Industrial research (CSIR), and the University of the North

Magíster en Gestión y Dirección de Empresas / El presente trabajo, analiza la metodología de Gestión de Proyectos utilizada en el Proyecto Óxidos Encuentro de Antofagasta Minerals S.A., y se compara descriptivamente con los estándares utilizados por la industria minera chilena, y mundialmente utilizados en el área de Gestión de Proyectos, como lo son PMBOK del Project Management Institute (PMI), y la metodología FEL de Independent Project Analysis (IPA). También, se analiza el tipo de contratación utilizada, comparándola con la de un contrato tipo EPCM para la etapa de ejecución, de forma de identificar diferencias, ventajas y desventajas. La metodología utilizada por el Proyecto OXE, consistió en que el Mandante asumió el gerenciamiento del proyecto, contrató por separado la ingeniería, realizó por su cuenta las compras y contratos, licitó y contrató la construcción, y por consiguiente, asumió la mayor parte de los riesgos de la ejecución. De acuerdo al análisis comparativo realizado respecto a PMBOK para la Ejecución de Procesos y para las Áreas de Conocimiento , se puede indicar que el Proyecto OXE cumple todas las recomendaciones y lineamentos definidos y compiladas por PMI para el desarrollo de proyectos de inversión de capital. Sin embargo, se recomienda realizar mejoras en las áreas de conocimiento de Gestión de Calidad y Adquisiciones, de manera de robustecer el Modelo de Gestión propuesto. Se destaca que las áreas de Gestión de Interesados, de Riesgos, de Recursos Humanos, Tiempo y Costos, fueron abordadas en forma adecuada y sobresaliente, permitiendo capitalizar las oportunidades que se dieron en el transcurso del proyecto. Según la metodología FEL de IPA, el análisis comparativo indica que los procedimientos ADS de AMSA se encuentran alineados y que fueron correctamente utilizados en el Proyecto OXE. Sin embargo, existen doce recomendaciones VIPs de IPA para el desarrollo de proyectos, las cuales se cumplen parcialmente, generándose oportunidades de mejora respecto a la utilización de software 3D, minimización de residuos, confiabilidad del proceso, mantenimiento preventivo y optimización energética. Respecto a la contratación tipo EPCM, se señala que el Proyecto OXE, consideró un equipo de profesionales experimentados internamente que administraran a los contratistas de ingeniería, de empresas colaboradoras en diversas áreas, de construcción y algunos EPC. Con ello, el equipo del mandante desarrolló el proyecto y servicios, pero no contaba con todos los sistemas y procedimientos que utilizan y poseen las empresas especialistas en EPCM, y a su vez fue limitado por los lineamientos corporativos de AMSA. Sin embargo, se ejecutaron acciones que permitieron disminuir las brechas existentes con un contratista tipo EPCM y se realizó un adecuado seguimiento de Riesgos, Costos y Plazos, que permitieron alcanzar gran parte de los factores de éxitos definidos, y cumplir con la mayoría de las directrices de PMBOK y FEL.