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The continuous high demand on permanent magnets in industries opened new research plateau to develop alternative magnetic material. The current used permanent magnet materials in the market still suffer from high cost and insufficient magnetic or thermal properties. The central focus of this dissertation work is the optimization of cobalt carbide based nanomaterial by means of modifying polyol synthesis assisted by nucleation agent and systematic statistics using JMP software tool. In most existing literatures, producing cobalt carbide (Co2C or Co3C) lack reproducibility and consistency resulting in nonsolid magnetic properties results. The practical requirements for cobalt carbide to be used as permanent magnet are high coercivity (Hc), high magnetization (Ms), resulting in a high-energy product (HcxMs). Previous literatures have shown coercivities of 1.5 to 2.5 kOe for cobalt carbides under aggressive temperatures conditions (300oC) or after aligning the particles under magnetic field. A statistical guided method performed a sequence of experiments toward producing high coercivities using surface response design. Primarily, the statistical study to optimize cobalt carbide was made by analyzing experimental condition to fulfill high magnetic properties with tuned conditions as much as possible. Therefore, having the advantage for superior control on process variable when shifting cobalt carbide for scale up production in flow chemistry set up using microreaction system (MMRS). The optimization is based upon selecting the most important conditions in polyol reaction to produce cobalt carbide (Co2C or Co3C) and feed JMP software model e.g. reaction temperature, reaction time, and or precursor concentration…etc. These factors called (effects) used to design experiments and generate tables to run minimum experiments. Points of each effect (levels) are selected based on previous knowledge and experience with the synthesis. The output called (response) can be any of the magnetic properties of our interest e.g. magnetization (Ms), coercivity (Hc), or energy magnetic product (HcxMs). In the first model fit of cobalt carbide magnetic was studied in a polyol reaction to increase its magnetic energy product and optimize the experimental conditions. The results disclosed increase in magnetic energy product (6.2 MGOe) when validating the prediction model conditions suggested by JMP: shorter reaction time, and lower precursor concentration conditions at maximum reaction temperature. Finally, to my knowledge studying the effect of the nucleating agent to alter cobalt carbide growth have not been studied so far. Therefore, statistical study design using central composite design (CCD) to investigate the nucleating agent effect of silver nitrite on cobalt carbide coercivity was made. The importance of nucleating agent on coercivity is vigorous to attain and control the growth direction of cobalt carbide nanoparticles. This is due to the shape anisotropy contribution to enhance coercivity unlike weak shape anisotropy attributed to agglomeration of nanoparticles demonstrated in previous studies. Enhancement of coercivity reached 3 kOe with aspect ratio control as a function of silver nitrite concentration under lower reaction temperature. The continuous high demand on permanent magnets in industries opened new research plateau to develop alternative magnetic material. The current used permanent magnet materials in the market still suffer from high cost and insufficient magnetic or thermal properties. The central focus of this dissertation work is the optimization of cobalt carbide based nanomaterial by means of modifying polyol synthesis assisted by nucleation agent and systematic statistics using JMP software tool. In most existing literatures, producing cobalt carbide (Co2C or Co3C) lack reproducibility and consistency resulting in nonsolid magnetic properties results. The practical requirements for cobalt carbide to be used as permanent magnet are high coercivity (Hc), high magnetization (Ms), resulting in a high-energy product (HcxMs). Previous literatures have shown coercivities of 1.5 to 2.5 kOe for cobalt carbides under aggressive temperatures conditions (300oC) or after aligning the particles under magnetic field. A statistical guided method performed a sequence of experiments toward producing high coercivities using surface response design. Primarily, the statistical study to optimize cobalt carbide was made by analyzing experimental condition to fulfill high magnetic properties with tuned conditions as much as possible. Therefore, having the advantage for superior control on process variable when shifting cobalt carbide for scale up production in flow chemistry set up using microreaction system (MMRS). The optimization is based upon selecting the most important conditions in polyol reaction to produce cobalt carbide (Co2C or Co3C) and feed JMP software model e.g. reaction temperature, reaction time, and or precursor concentration…etc. These factors called (effects) used to design experiments and generate tables to run minimum experiments. Points of each effect (levels) are selected based on previous knowledge and experience with the synthesis. The output called (response) can be any of the magnetic properties of our interest e.g. magnetization (Ms), coercivity (Hc), or energy magnetic product (HcxMs). In the first model fit of cobalt carbide magnetic was studied in a polyol reaction to increase its magnetic energy product and optimize the experimental conditions. The results disclosed increase in magnetic energy product (6.2 MGOe) when validating the prediction model conditions suggested by JMP: shorter reaction time, and lower precursor concentration conditions at maximum reaction temperature. Finally, to my knowledge studying the effect of the nucleating agent to alter cobalt carbide growth have not been studied so far. Therefore, statistical study design using central composite design (CCD) to investigate the nucleating agent effect of silver nitrite on cobalt carbide coercivity was made. The importance of nucleating agent on coercivity is vigorous to attain and control the growth direction of cobalt carbide nanoparticles. This is due to the shape anisotropy contribution to enhance coercivity unlike weak shape anisotropy attributed to agglomeration of nanoparticles demonstrated in previous studies. Enhancement of coercivity reached 3 kOe with aspect ratio control as a function of silver nitrite concentration under lower reaction temperature.

En tant que polymère de grande diffusion, les applications du polypropylène isotactique (PP) sont limitées par sa faible resistance au choc. D'après la relation structure - propriétés, sa résistance au choc peut être améliorée en contrôlant sa structure. Dans ces travaux, différents types d'agents nucléants ont été utilsés pour promouvoir la formation des cristaux de type bêta et de mélanges de deux PP de masses molaires différentes. Les propriétés mécaniques, le comportement à la rupture, et la morphologie cristalline ont été étudiés. Les influences du type et de la teneur en peroxyde et agent nucléant sur la morphologie cristalline et les propriétés mécaniques ont aussi été explorées. Un agent nucléant suporté sur des nanotubes de carbone multi-parois (MWCNT) a été utilisé pour modifier la structure cristalline du PP, ce qui a permis d'augumeter sa résistance au choc 7 fois comparée à celle du PP vierge et 3 fois comparée à celle du PP cristallisé en phase bêta. Cette importante augmentation en resistance au choc peut être attribuée à la formation des trans-cristaux de type bêta qui est favorisée par l?agent nucléant supporté sur les MWCNT / As a commodity polymer, the applications of isotactic polypropylene (PP) are limited by its low impact strength. Based on the structure-property relationship, its impact strength could be improved by controlling its structure. In this study, different kinds of nucleating agents were used to promote the formation of beta crystals of PP as well as mixtures of two PPs of different molar masses. The mechanical properties, fracture behaviour, and crystalline morphology were investigated. The effects of the type and content of the peroxide and nucleating agent on the crystalline structure and mechanical properties of the PP were also explored. A multi-walled carbon nanotude (MWCNT) supported nucleating agent was introduced to modify the crystalline structure of PP and the impact strength of the resulting PP was 7 times that of the pure PP and more than 3 times that of beta nucleated PP. The large increase in the impact strength was attributed to the formation of beta transcrystalline morphology which was promoted by the MWCT supported nucleating agent

Certain organisms, including some bugs (both insects and microbes) are able to survive low temperatures by the production of either ice nucleating proteins (INPs) or antifreeze proteins (AFPs). INPs direct crystal growth by inducing rapid ice formation whereas AFPs adsorb to ice embryos and decrease the temperature at which the ice grows. We have also shown that certain AFPs can inhibit the crystallization of clathrate hydrates and eliminate more rapid recrystallization or “memory effect”. Here we examine several bacterial species with iceassociating properties for their effect on tetrahydrofuran (THF) hydrate crystallization. The bacteria Chryseobacterium sp. C14, which shares the ice recrystallization inhibition ability of AFPs, increased induction time to THF hydrate crystallization in isothermal experiments. In an effort to understand the association between AFPs and THF hydrate we have produced bacterially-expressed AFPs as probes for hydrate binding. Although the structure of hydrates is clearly distinct from ice, the apparent potential for these products to perturb clathrate hydrate growth compels us to explore new techniques to uncover “green inhibitors” for hydrate binding.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 5 uppsatser.

Submitted by Marcio Emanuel Paixão Santos (marcio.santos@ucsal.br) on 2018-06-21T21:27:01Z No. of bitstreams: 1 DISSERTACAOFRANCISCOPIMENTAJUNIOR.pdf: 1939347 bytes, checksum: ba72edebc4b2afc4a468623041f340c5 (MD5) / Approved for entry into archive by Linda Bulhosa (linda.gomes@ucsal.br) on 2018-06-25T13:23:30Z (GMT) No. of bitstreams: 1 DISSERTACAOFRANCISCOPIMENTAJUNIOR.pdf: 1939347 bytes, checksum: ba72edebc4b2afc4a468623041f340c5 (MD5) / Made available in DSpace on 2018-06-25T13:23:30Z (GMT). No. of bitstreams: 1 DISSERTACAOFRANCISCOPIMENTAJUNIOR.pdf: 1939347 bytes, checksum: ba72edebc4b2afc4a468623041f340c5 (MD5) Previous issue date: 2017-08-22 / Esta dissertação trata do uso de técnicas nucleadoras na recuperação de áreas degradadas em áreas urbanas fim de promover serviços ambientais, diante da necessidade da conservação e do uso de técnicas inovadoras na recuperação. A expansão urbana contribui para o aumento gradativo das áreas degradadas, contribuindo para a fragmentação de ecossistemas e perdas em biodiversidade. A não gestão de áreas degradadas contribui para incremento de áreas improdutivas, a formação de processos erosivos, empobrecimento do solo e comprometimento de áreas adjacentes às áreas degradadas. Existem modelos de recuperação dessas áreas, que se baseiam em especial no plantio de mudas, com o foco mais dendrológico e que adota práticas de silvicultura, no entanto vem se discutindo o uso de modelos de restauração que buscam o retorno da estabilidade e integridade biológica, sendo esta técnica denominada de nucleação, baseada em processos ecológicos. Também é importante proporcionar meios de subsistência e serviços ambientais das terras degradadas, identificando possíveis medidas que acentue a recuperação e os serviços ambientais prestados. Com esse enfoque, o presente trabalho tem como objetivo verificar o potencial da nucleação no fornecimento de serviços ambientais e na recuperação de áreas degradadas em áreas urbanas. O trabalho é composto por três capítulos que tratam dos serviços ambientais, de métodos iniciais de restauração e de uma proposta de protocolo de avaliação de serviços ambientais na recuperação de áreas degradadas em áreas urbanas, respectivamente. No trabalho verifica-se que a nucleação possui um potencial muito expressivo no fornecimento de serviços ambientais, ainda que através de práticas simples como a transposição de solo e serapilheira, no entanto os planos e programas de recuperação devem estar alinhados com a vocação e a necessidade da área degradada e do contexto do seu entorno principalmente se tratando de áreas urbanas. / This dissertation deals with the use of nucleating techniques in the recovery of degraded areas in urban conservation units in order to promote environmental services, in view of the need for conservation and the use of innovative recovery techniques. Urban expansion contributes to the gradual increase of degraded areas, contributing to the fragmentation of ecosystems and losses in biodiversity. The non-management of degraded areas contributes to the increase of unproductive areas, the formation of erosive processes, the impoverishment of the soil and the compromise of areas adjacent to degraded areas. There are models of recovery of these areas, which are based in particular on planting of seedlings, with a more dendrological focus and adopting silvicultural practices, however the use of restoration models that seek the return of stability and biological integrity, Being this technique called nucleation, based on ecological processes. It is also important to provide livelihoods and environmental services for degraded lands, identifying possible measures that enhance recovery and environmental services provided. With this focus, the present work aims to verify the potential of nucleation in the provision of environmental services and in the recovery of degraded areas in urban conservation units. The work consists of three chapters dealing with environmental services, initial restoration methods and a proposal for a protocol for the evaluation of environmental services in the recovery of degraded areas in urban areas, respectively. In the work, it is verified that nucleation has a very expressive potential in the provision of environmental services, although through simple practices such as soil and litter transposition, however recovery plans and programs must be in line with vocation and need of the degraded area and of the context of its environment, especially in urban conservation units.

The Atlantic Forest biome is considered one of the most important regions for biodiversity conservation in the world due to the combination of high species richness and a high number of endemic species. Ecological restoration strategies based on the principles of nucleation assist in the return of functions and ecological processes of disturbed areas, in order to facilitate and accelerate the process of ecological succession, respecting their natural diversity. The present work aims to analyze the efficiency of different nucleating strategies for the ecological restoration of forest ecosystems in the Atlantic Forest biome of Rio Grande do Sul, Brazil. The study was developed in riparian forests around springs, with predominance of eucalyptus productive matrix, in Itaara, RS. For this, were planted 300 seedlings of ten species arranged in 60 nuclei. Ten artificial perches were also installed with seed collectors and 10 witness collectors, in addition to the monitoring of the avifauna. Total height, DAS, survival rates and reproductive phenology (flowering and fruiting) were evaluated. Survival rates showed significant differences. Allophylus edulis, Campomanesia xanthocarpa, Eugenia involucrata, Luehea divaricata, Parapiptadenia rigida, Prunus myrtifolia, Psidium cattleianum and Schinus terebinthifolius showed 100% survival. Cupania vernalis was the only one to present a critical rate of 45%. Increases in height and in DAS also showed significant differences, with most of the pioneer species presenting the highest averages for both variables. Schinus terebinthifolius and Psidium cattleianum showed flowering and fruiting 12 months after planting. Pioneer species were the most efficient in survival and growth than species of more advanced successional stage. Schinus terebinthifolius was the best performing species for the evaluated variables. A total of 4,089 seeds belonging to 12 species were sampled on collectors. Of this total, 2,110 (51.60%) seeds were sampled in the collectors under artificial perches and 1,979 (48.40%) sampled in the control collectors. There was no significant difference between the treatments by the Kruskal-Wallis test at a 5% probability level for the seeds number. Tyrannus melancholicus was the only species to use the perches. The use of artificial perches was not efficient for the supply of plant propagules nor for the attraction of birds. It was concluded that the arrangement in nuclei allowed the satisfactory development of most species, and that the productive matrix of eucalyptus surrounding the area negatively influenced the processes of seed dispersal. / O bioma Mata Atlântica é considerado uma das regiões mais importantes para a conservação da biodiversidade no mundo, devido a combinação de alta riqueza de espécies e elevadas taxas de endemismo. As estratégias de restauração ecológica com base nos princípios da nucleação auxiliam no retorno das funções e dos processos ecológicos de áreas perturbadas, visando facilitar e acelerar o processo de sucessão ecológica, respeitando a sua diversidade natural. O presente trabalho tem como objetivo monitorar e analisar a eficiência de duas técnicas nucleadoras (plantio em núcleos e poleiros artificiais) para a restauração ecológica de ecossistemas florestais no bioma Mata Atlântica, no Sul do Brasil. Foi desenvolvido em matas ciliares no entorno de nascentes, com predominância de matriz produtiva de eucalipto, no munícipio de Itaara, RS. Para isso, foram plantadas 300 mudas de dez espécies dispostas em 60 núcleos. Também foram instalados 10 poleiros artificias com coletores de sementes e 10 coletores testemunhas, além de ser realizado o monitoramento da avifauna. Nas mudas, avaliaram-se altura total, diâmetro a altura do solo (DAS), taxas de sobrevivência e fenologia reprodutiva. As taxas de sobrevivência apresentaram diferenças significativas de acordo com o teste Tukey ao nível de 5% de probabilidade. Allophylus edulis, Campomanesia xanthocarpa, Eugenia involucrata, Luehea divaricata , Parapiptadenia rigida , Prunus myrtifolia, Psidium cattleianum e Schinus terebinthifolius apresentaram 100% de sobrevivência. Eugenia uniflora obteve 92,9% de sobrevivência e Cupania vernalis apresentou taxa considerada crítica de 45%. Os incrementos em altura total e em DAS também apresentaram diferenças significativas de acordo com o teste de Kruskal-Wallis ao nível de 5% de probabilidade, sendo que a maioria das espécies pioneiras apresentaram as maiores médias para ambas as variáveis. Schinus terebinthifolius e Psidium cattleianum apresentaram floração e frutificação 12 meses após o plantio. Espécies pioneiras foram as mais eficientes em sobrevivência e crescimento do que espécies de estágio sucessional mais avançado. Schinus terebinthifolius foi a espécie de melhor desempenho para as variáveis avaliadas. Nos coletores foram amostradas 4.089 sementes pertencentes a 12 espécies. Desse valor total, 2.110 (51,60%) sementes foram amostradas sob poleiros artificiais e 1.979 (48,40%) amostradas nos coletores testemunha. Não houve diferença significativa entre os tratamentos pelo teste de Kruskal-Wallis ao nível de 5% de probabilidade para o número de sementes. Tyrannus melancholicus foi a única espécie a utilizar os poleiros. O uso de poleiros artificiais não foi eficiente para o aporte de propágulos vegetais e nem para a atração de aves. Conclui-se que o arranjo em núcleos permitiu o desenvolvimento satisfatório da maioria das espécies, e que a matriz produtiva de eucalipto circundante à área influenciou negativamente nos processos de dispersão de sementes.

A change in atmospheric aerosol particles, especially cloud condensation nuclei (CCN) and ice-nucleating particles (INPs), is bound to impact cloud properties, precipitation and cloud radiative effects. In this thesis, two field campaigns were carried out in two representative locations, i.e. the anthropogenic polluted environment at Cyprus and the marine-dust intersect environment at Cabo Verde (a.k.a. Cape Verde) to understand the role of CCN and INPs over the tropical and subtropical regions in the northern hemisphere. On-line aerosol physical measurements were performed and samples from different environ- mental compartments were examined with respect to INPs: the oceanic sea surface microlayer (SML), underlying water (ULW), cloud water and atmospheric filters. Both measurement sites differ in aerosol properties, such as particle number size distribution, CCN and INP concentrations and CCN-derived particle hygroscopicity, due to different environment backgrounds and air mass origins. Aerosol particles at Cyprus were dominated by anthropogenic pollution, with small contributions of sea spray aerosol (SSA) and mineral dust. Particle aging process were observed through changes in CCN-derived particle hygroscopicity. New particle formation events with subsequent growth of the particles into the CCN size range were observed. INPs mainly originated from long-range transport. And anthropogenic pollution were found to be inefficient INPs at temperature range >−25 ◦C. However, aerosol particles at Cabo Verde featured a marine background with intrusions of dust. Dust and marine aerosols featured clearly different PNSDs. CCN number concentration at a supersaturation of 0.30% during the strongest observed dust periods was about 2.5 times higher than during marine periods. However, the CCN-derived hygroscopicity for marine and dust periods shows no significant difference. INPs at Cabo Verde were mainly in the supermicron size range, with a large contribution of biological particles. When comparing atmospheric INP number concentration to those found in seawater, it can be concluded that SSA only contributed a minor fraction to the atmospheric INP population.:1 Introduction 2 Methodology 3 Results and Discussion 4 Summary and Conclusions 5 Outlook Appendix Bibliography / Veränderungen im atmosphärischen Aerosol, speziell bei Wolkenkondensationskernen (CCN) und eisnukleierenden Partikeln (INPs), haben Auswirkungen auf Wolkeneigenschaften wie Niederschlagsbildung und Strahlung. Für die hier vorgelegte Arbeit wurden zwei Feldmesskampagnen durchgeführt, im anthropogen verschmutzten Zypern und auf Cabo Verde (alias Kap Verde), einer Schnittstelle zwischen Meer und Wüste. Ziel war es, die Rolle von CCN und INPs in den tropischen und subtropischen Regionen der nördlichen Hemisphäre besser zu verstehen. Es wurden aerosol-physikalische online Messungen durchgeführt und verschiedene Proben auf INPs hin untersucht: die Meeresoberflächen-Mikroschicht (SML), das darunter liegende Wasser (ULW), das Wolkenwasser und atmosphärische Filter. Die beiden verschiedenen Orte an denen die Messkampagnen stattfanden unterscheiden sich in den Aerosoleigenschaften wie z.B. Partikelanzahlgrößenverteilung (PNSD), CCN- und INP-Konzentration und der von CCN abgeleiteten Partikelhygroskopizität. Grund hierfür sind Unterschiede in der Umgebung und der Luftmassenherkunft. Die Aerosolpartikel auf Zypern wurden von anthropogener Verschmutzung dominiert, mit kleinen Beiträgen von Partikeln aus Meeres-Gischt (SSA) und Mineralstaub. Partikelalterung ging einher mit einer Veränderung der Hygroskopizität der CCN. Partikelneubildung wurde beobachtet, mit anschließendem Wachstum der Partikel bis in den CCN-Größenbereich. INPs stammen hauptsächlich aus Ferntransport, und Partikel aus anthropogener Verschmutzung waren ineffiziente INPs im Temperaturbereich >−25 ◦C. Das Aerosol in Cabo Verde speiste sich sowohl aus marinen Quellen als auch aus Wüstenstaub. Staub und marines Aerosol wiesen sehr verschiedene PNSDs auf. Die CCN-Anzahlkonzentration bei 0,30% Übersättigung war während der stärksten Staubperioden etwa 2,5 Mal höher als während der marinen Perioden. Die aus CCN abgeleitete Hygroskopizität zeigte jedoch keinen signifikanten Unterschied für marine und Staubperioden. Die INPs in Cabo Verde waren zum Großteil größer als ein Mikrometer, und waren zum Großteil biogenen Ursprungs. Aus dem Vergleich der atmosphärischen INP-Anzahlkonzentration mit der im Meerwasser gefundenen kann man schließen, dass SSA nur einen geringen Anteil zur atmosphärischen INP-Population beitrug.:1 Introduction 2 Methodology 3 Results and Discussion 4 Summary and Conclusions 5 Outlook Appendix Bibliography

Made available in DSpace on 2017-07-21T20:42:42Z (GMT). No. of bitstreams: 1 Cristiano da Silva.pdf: 5271302 bytes, checksum: 25a5bdf4a3671c9a497d93fa788662df (MD5) Previous issue date: 2014-01-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work aims at verifying the influence of processing by high energy ball milling of titanium diboride (TiB2), to increase the effect of grain refining of high-purity aluminum. Various mills were carried out by varying the ratio of the initial TiB2 and aluminum charges. After obtaining the milling products, they were compressed in a cylindrical array as a uniaxial compressive stress of 100MPa, some were later sintered at 600°C for 30 minutes. The tablets were introduced in the metal bath of aluminum and castings at 800°C in thermal analysis cups. In metal baths, experiments with and without the presence of titanium as a solute, in addition to the variation of the content of TiB2 (0.15 and 0.30 wt%) can be observed. The results indicate a significant reduction in grain size, especially in the samples were nucleated with pellets which were sintered before being added to the bath. / Este trabalho, tem por objetivo, verificar a influência do processamento por moagem de alta energia em moinho de bolas, do diboreto de titânio (TiB2), visando aumentar o efeito de refino de grãos do alumínio de alta pureza. Várias moagens foram realizadas, variando-se a razão de alumínio e TiB2 das cargas iniciais. Após a obtenção dos produtos de moagem, os mesmos foram compactados em uma matriz cilíndrica uniaxial como uma tensão de compressão de 100MPa, algumas posteriormente foram sinterizadas à 600°C por 30 minutos. As pastilhas foram introduzidas no banho metálico de alumínio e vazadas à 800°C em copos para análise térmica. Nos banhos metálicos, experimentos sem e com a presença de titânio como soluto, além da variação do teor de TiB2 (0,15 e 0,30%p) também podem ser observados. Os resultados indicam uma redução significativa no tamanho de grão, especialmente nas amostras que foram nucleadas por pastilhas que foram sinterizadas antes de serem adicionadas ao banho.

Disputats. Universität Hohenheim, 2002. / Haves kun i elektronisk udg. Thesis (Ph.D.). 41 ill., 5 tables; approx. 200 ref. Summaries (En, Ge).