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Modelling of the deformation behaviour of a magnetic hydrogel in a magnetic field gradientCzichy, Charis, Odenbach, Stefan 27 November 2024 (has links)
An ink made of alginate and methylcellulose with embedded magnetite microparticles was developed for extrusion printing. Constructs, so-called scaffolds, are colonised with cells which can be activated by mechanical stimulation. In this work, a defined magnetic field gradient is applied to achieve non-contact deformation. However, the deformation behaviour or relevant material parameters of the hybrid material are unknown. While the properties were determined with experiments adapted to hydrogels, a separate experimental set-up for micro-computed tomography, adapting the Maxwell configuration, was developed to investigate the deformation behaviour. These analyses were performed depending on ageing and particle concentration. For these tests, strands were used as bending beams, since these are simple and well known systems. Firstly, a model for the bending curve was erected, which defines a range in which the real bending curve would be expected. It was compared with the measured bending curves. There was very good agreement for the first days. On day 14, the measured bending curves were still within the calculated range, but at the lower limit due to the shortcomings of the model as the violation of the small deformations condition at this point. Secondly, the bending as a function of incubation duration was observed by a series of radiograms when a magnetic field gradient was applied. From this, a functional approach was formulated to describe the system response. Some parameters have already been identified, for others a proposal is given. Thirdly, microscopic analyses were carried out to observe the effects of the field gradient on particle distribution and structure. It was revealed that a homogeneous particle distribution was found even after 2.5 h. Also, in the direction of the field gradient, no chains were formed and no damage of the network could be detected. The obtained results show, that the material is suitable for mechanical stimulation.
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Preparation and characterisation of encapsulation magnetic metal iron oxide nanoparticlesAl-Saadi, Ali January 2012 (has links)
One of the most challenging goals in nanoparticle research is to develop successful protocols for the large-scale, simple and possibly low-cost preparation of morphologically pure nanoparticles with enhanced properties. The work presented in this thesis was focused on the synthesis, characterisation and testing of magnetic nanoparticles and their potential applications. There are a number of magnetic nano-materials prepared for specific applications such as metal oxide nanoparticles encapsulated with various porous materials including Fe₃O₄/Fe₂O₃ coated with soft bio-organic materials such as glycol chitosan and bovine serum albumin and hard materials such as silica (SiO₂) and zinc sulphide (ZnS). The preparation of these materials was achieved principally by bottom-up methods with different approaches including micro-emulsion, precipitation, electrostatic and thermolysis processes. The thesis also presents the uses of various analytical techniques for characterising different types of nano-materials including Attenuated Total Reflection Fourier Transformer Infrared Vibrational Spectroscopy (ATR-FTIR), Ultraviolet Visible- Near Infrared (UV-Vis-NIR) Spectroscopy, Zeta Potentiometric Surface Charge Analysis, Superconducting Quantum Interference Device (SQUID) and Vibration Sample Magnetometry (VSM) for magnetic analysis and powder X-Ray Diffraction (XRD) for crystallographic pattern analysis. There are many applications of magnetic nanoparticles, including nano-carriers for biological and catalytic reagents. The magnetic nanoparticles can facilitate separation in order to isolate the carriers from solution mixtures as compared to many inefficient and expensive classic methods, which include dialysis membrane, electrophoresis, ultracentrifugation, precipitation and column separation methods. There are six key chapters in this thesis: the first chapter introduces the up-to-date literature regarding magnetic nano-materials. The uses of magnetic nano-materials in drug binding and for protein separation are discussed in the second and third chapters. The fourth chapter presents the use of magnetic nanoparticle in conjunction with a photo-catalytic porous overlayer for the photo-catalytic reduction of organic molecules. The fifth chapter describes different analytical techniques used for the characterisation of nanoparticles and the underlying principles and the experimental details are also given. The sixth chapter summarises the results and provides an overview of the work in a wider context of future applications of magnetic nanoparticles.
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Formation of mixed Fe"-Fe"' oxides and their reactivity to catalyze chemical oxidation : remediation of hydrocarbon contaminated soils / Formation des composés mixtes Fe"-Fe"' et réactivité catalytique pour l'oxydation chimique : remédiation des sols contaminés par les hydrocarburesUsman, Muhammad 17 November 2011 (has links)
Le thème principal de cette recherche est la remédiation des sols contaminés par des hydrocarbures en utilisant des traitements d'oxydation chimique à pH neutre. Les minéraux à base de fer sont susceptibles de catalyser cette réaction d'oxydation. L'étude concerne donc dans un premier temps la synthèse des minéraux réactifs contenant des espèces FeII et FeIII (la magnétite et la rouille verte) et, dans un second temps, leur utilisation pour catalyser l'oxydation chimique. Les procédés d'oxydation testés incluent l'oxydation de type « Fenton-like (FL) » et de type persulfate activé (AP). La formation de la magnétite et de la rouille verte a été étudiée par des transformations abiotiques de différents oxydes ferriques (ferrihydrite, goethite, hématite et lépidocrocite) mis en présence de cations FeII. La magnétite a été utilisée pour catalyser les oxydations (FL et AP) dans la dégradation des hydrocarbures aliphatiques et aromatiques polycycliques (HAP) à pH neutre. Une dégradation importante des hydrocarbures aliphatiques a été obtenue par ces deux oxydants, aussi bien pour des pétroles dégradés naturellement que pour un pétrole brut. L'oxydation catalysée par la magnétite a également été efficace pour la remédiation de deux sols contaminés par HAP provenant d'anciens sites de cokerie. Aucun sous-produit n'a été observé dans nos expériences d'oxydation. En revanche, une très faible dégradation des hydrocarbures a été observée lorsque les espèces FeII solubles ont été utilisées comme catalyseur. Des expériences d'oxydation ont également été réalisées en colonne. Ces études d'oxydation ont révélé l'importance du type de catalyseur utilisé pour l'oxydation, la disponibilité des HAP dans les sols et l'effet de la matrice du sol. Les résultats suggèrent que la magnétite peut être utilisée comme source de fer pour activer les deux oxydations par Fenton-like et persulfate à pH neutre. Ce travail a de fortes implications sur la remédiation par oxydation chimique in situ des sols pollués par des hydrocarbures / The main theme of this research is the use of reactive iron minerals in the remediation of hydrocarbon contaminated soils via chemical oxidation treatments at circumneutral pH. The contribution of this thesis is two-fold including the abiotic synthesis of mixed FeII-FeIII oxides considered as reactive iron minerals (magnetite and green rust) and their use to catalyze chemical oxidation. Oxidation methods tested in this study include Fenton-like (FL) and activated persulfate oxidation (AP). The formation of magnetite and green rust was studied by abiotic FeII-induced transformations of various ferric oxides like ferrihydrite, goethite, hematite and lepidocrocite. Then, the ability of magnetite was tested to catalyze chemical oxidation (FL and AP) for the degradation of aliphatic and polycyclic aromatic hydrocarbons (PAHs) at circumneutral pH. Significant degradation of oil hydrocarbons occurring in weathered as well as in crude oil was obtained by both oxidants. Magnetite catalyzed oxidation was also effective for remediation of two PAHs contaminated soils from ancient coking plant sites. No by-products were observed in all batch slurry oxidation systems. Very low hydrocarbon degradation was observed when soluble FeII was used as catalyst under the same experimental conditions. Magnetite also exhibited high reactivity to catalyze chemical oxidation in column experiments under flow through conditions. Oxidation studies revealed the importance of catalyst type for oxidation, PAHs availability in soils and the soil matrix effect. Results of this study suggest that magnetite can be used as iron source to activate both Fenton-like and persulfate oxidation at circumneutral pH. This study has important implications in the remediation of hydrocarbon polluted soils through in-situ chemical oxidation
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Removal and recovery of copper ion (Cu²⁽) from electroplating effluent by pseudomonas putida 5-X immobilized on magnetites.January 1996 (has links)
by Sze Kwok Fung Calvin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 118-130). / Acknowledgement --- p.i / Abstract --- p.ii / Content --- p.iv / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Literature review --- p.1 / Chapter 1.1.1 --- Heavy metals in the environment --- p.1 / Chapter 1.1.2 --- Heavy metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Electroplating industry in Hong Kong --- p.6 / Chapter 1.1.4 --- Chemistry and toxicity of copper in the environment --- p.7 / Chapter 1.1.5 --- Methods of removal of heavy metal from industrial effluent --- p.9 / Chapter A. --- Physico-chemical methods --- p.9 / Chapter B. --- Biological methods --- p.9 / Chapter 1.1.6 --- Methods of recovery of heavy metal from metal-loaded biosorbent --- p.17 / Chapter 1.1.7 --- The physico-chemical properties of magnetites --- p.18 / Chapter 1.1.8 --- Magnetites for water and wastewater treatment --- p.19 / Chapter 1.1.9 --- Immobilized cell technology --- p.24 / Chapter 1.1.10 --- Stirrer-tank bioreactor --- p.26 / Chapter 1.2 --- Objectives of the present study --- p.28 / Chapter 2. --- Materials and Methods --- p.30 / Chapter 2.1 --- Selection of copper-resistant bacteria --- p.30 / Chapter 2.2 --- Culture media and chemicals --- p.30 / Chapter 2.3 --- Growth of the bacterial cells --- p.32 / Chapter 2.4 --- Immobilization of the bacterial cells on magnetites --- p.32 / Chapter 2.4.1 --- Effects of physical and chemical factors on the immobilization of the bacterial cells on magnetites --- p.34 / Chapter 2.4.2 --- Effects of pH on the desorption of bacterial cells from magnetites --- p.34 / Chapter 2.5 --- Copper ion uptake experiments --- p.35 / Chapter 2.6 --- Effects of physico-chemical and operational factors on the Cu2+ removal capacity of the magnetite-immobilized bacterial cells --- p.35 / Chapter 2.7 --- Transmission electron micrograph and scanning electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.36 / Chapter 2.7.1 --- Transmission electron micrograph --- p.36 / Chapter 2.7.2 --- Scanning electron micrograph --- p.37 / Chapter 2.8 --- Copper ion adsorption isotherm of the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.37 / Chapter 2.9 --- Recovery of adsorbed Cu2+ from the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.38 / Chapter 2.9.1 --- Effects of eluents on the Cu2+ removal and recovery capacity of the magnetite-immobilized cells --- p.38 / Chapter 2.9.2 --- Batch type multiple adsorption-desorption cycles of Cu2+ using ethylenediaminetetra-acetic acid (EDTA) --- p.39 / Chapter 2.10 --- Removal and recovery of Cu2+ from the electroplating effluent by a bioreactor --- p.39 / Chapter 2.10.1 --- Batch type multiple adsorption-desorption cycles using the copper solution and electroplating effluent --- p.39 / Chapter 2.10.2 --- Continuous type bioreactor to remove and recover Cu2+ from copper solution and electroplating effluent --- p.40 / Chapter 2.11 --- Statistical analysis of data --- p.43 / Chapter 3. --- Results --- p.44 / Chapter 3.1 --- Effects of physical and chemical factors on the immobilization of the bacterial cells on magnetites --- p.44 / Chapter 3.1.1 --- Effects of cells to magnetites ratio --- p.44 / Chapter 3.1.2 --- Effects of pH --- p.44 / Chapter 3.1.3 --- Effects of temperature --- p.44 / Chapter 3.2 --- Effects of pH on the desorption of bacterial cells from magnetites --- p.49 / Chapter 3.3 --- Copper ion uptake experiments --- p.49 / Chapter 3.4 --- Effects of physico-chemical and operational factors on the Cu2+ removal capacity of the magnetite-immobilized bacterial cells --- p.49 / Chapter 3.4.1 --- Effects of pH --- p.49 / Chapter 3.4.2 --- Effects of temperature --- p.53 / Chapter 3.4.3 --- Effects of retention time --- p.53 / Chapter 3.4.4 --- Effects of cations --- p.53 / Chapter 3.4.5 --- Effects of anions --- p.57 / Chapter 3.5 --- Transmission electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.62 / Chapter 3.6 --- Scanning electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.62 / Chapter 3.7 --- Copper ion adsorption isotherm of the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.68 / Chapter 3.8 --- Recovery of adsorbed Cu2+ from the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.68 / Chapter 3.8.1 --- Effects of eluents on the Cu2+ removal and recovery capacity of the magnetite-immobilized cells --- p.68 / Chapter 3.8.2 --- Batch type multiple adsorption-desorption cycles of Cu2+ using ethylenediaminetetra-acetic acid (EDTA) --- p.74 / Chapter 3.9 --- Removal and recovery of Cu2+ from the electroplating effluent by a bioreactor --- p.74 / Chapter 3.9.1 --- Batch type multiple adsorption-desorption cycles using the copper solution and electroplating effluent --- p.74 / Chapter 3.9.2 --- Continuous type bioreactor to remove and recover Cu2+ from copper solution and electroplating effluent --- p.81 / Chapter 4. --- Discussion --- p.89 / Chapter 4.1 --- Selection of copper-resistant bacteria --- p.89 / Chapter 4.2 --- Effects of physical and chemical factors on the immobilization of the bacterial cells on magnetites --- p.89 / Chapter 4.2.1 --- Effects of cells to magnetites ratio --- p.89 / Chapter 4.2.2 --- Effects of pH --- p.90 / Chapter 4.2.3 --- Effects of temperature --- p.91 / Chapter 4.2.4 --- Effects of pH on the desorption of bacterial cells from magnetites --- p.92 / Chapter 4.3 --- Copper ion uptake experiments --- p.93 / Chapter 4.4 --- Effects of physico-chemical and operational factors on the Cu2+ removal capacity of the magnetite-immobilized bacterial cells --- p.94 / Chapter 4.4.1 --- Effects of pH --- p.95 / Chapter 4.4.2 --- Effects of temperature --- p.96 / Chapter 4.4.3 --- Effects of retention time --- p.97 / Chapter 4.4.4 --- Effects of cations --- p.98 / Chapter 4.4.5 --- Effects of anions --- p.101 / Chapter 4.5 --- Transmission electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.101 / Chapter 4.6 --- Scanning electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.102 / Chapter 4.7 --- Copper ion adsorption isotherm of the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.103 / Chapter 4.8 --- Recovery of adsorbed Cu2+ from the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.104 / Chapter 4.8.1 --- Effects of eluents on the Cu2+ removal and recovery capacity of the magnetite-immobilized cells --- p.104 / Chapter 4.8.2 --- Batch type multiple adsorption-desorption cycles of Cu2+ using ethylenediaminetetra-acetic acid (EDTA) --- p.105 / Chapter 4.9 --- Removal and recovery of Cu2+ from the electroplating effluent by a bioreactor --- p.107 / Chapter 4.9.1 --- Batch type multiple adsorption-desorption cycles using the copper solution and electroplating effluent --- p.107 / Chapter 4.9.2 --- Continuous type bioreactor to remove and recover Cu2+ from copper solution and electroplating effluent --- p.108 / Chapter 5. --- Conclusion --- p.110 / Chapter 6. --- Summary --- p.112 / Chapter 7. --- References --- p.115
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The redox and iron-sulfide geochemistry of Salt Pond and the thermodynamic constraints on native magnetotactic bacteriaCanovas, Peter A January 2006 (has links)
Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006. / Includes bibliographical references (p. 64-68). / Salt pond is a meromictic system with an outlet to the sea allowing denser seawater to occupy the monimolimnion while the mixolimnion has relatively low salinity and is the site of greater mixing and microbial activity. The density contrast between the two layers allows for a unique geochemical environment characterized by steep redox gradients at the interface. This chemocline is a habitat for magnetotactic bacteria (MB), and the spatial and temporal distribution of MB in the system along with geochemical (Fe2+, H2S, pH, 02 (aq), etc.) profiles have been analyzed from 2002 - 2005. It has been previously observed that magnetite-producing cocci occupy the top of the chemocline and greigite-producing MB occur at the base of the chemocline and in the sulfidic hypolimnion. This distribution may be attributed to analyte profiles within the pond; depth profiles show a sudden drop of dissolved oxygen (DO) at the chemocline associated with an increase in dissolved Fe (II) concentrations that peak where both 02 and H2S are low. In the sulfidic hypolimnion, Fe (II) concentrations decrease, suggesting buffering of Fe(II) by sulfide phases. / (cont.) Maximum concentrations of iron (II) and sulfide are 3 1 gM and 3 mM, respectively. Stability diagrams of magnetite and greigite within EH/pH space and measured voltammetric data verify fields of incomplete oxidation resulting in the production of elemental sulfur, thiosulfate and polysulfides. Calculations of the Gibbs free energy in the Salt Pond chemocline for potential microbial redox reaction involving iron and sulfur species indicate abundent potential energy available for metabolic growth. Oxidation of ferrous iron to ferrihydrite in the upper region of the chemocline consistantly has a yield of over -250 kJ/mol 02 (aq), - 12.5 times the proposed 20 kJ/mol minimum proposed by Schink (1997) necessary to sustain metabolic growth. This translates into biomass yields of ~ 0.056 mg dry mass per liter of upper chemocline water. If these numbers are applied to the dominant bacteria of the chemocline (MB that are 3% dry weight iron) then there could be up to ~ 1.68 mg of iron per liter of upper chemocline water just in the MB. / (cont.) This iron can be permanently sequestered by MB into the sediments after death because the organelles containing the iron phases are resistant to degredation. Geochemical and microbial processes relating to the cycling of iron heavily impact this system and perhaps others containing a chemocline that divides the water column into oxic and anoxic zones. / by Peter A. Canovas, III. / S.M.
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Preparação e caracterização de microesferas poliméricas à base de metacrilato de glicidila e divinilbenzeno com propriedades magnéticas / Preparation and characterization of polymeric microspheres based on glycidyl methacrylate and divinylbenzene with magnetic propertiesCarla do Nascimento Queiroz 31 March 2011 (has links)
Nesta Dissertação, foram sintetizadas microesferas poliméricas com propriedades magnéticas à base de metacrilato de glicidila e divinilbenzeno pela técnica de polimerização em suspensão. O material utilizado para conferir as propriedades magnéticas ao copolímero foi magnetita sintetizada no laboratório. Foram estudados os efeitos da modificação da magnetita com ácido oleico, da velocidade de agitação, do teor de agente reticulante, do teor de material magnético adicionado e do teor de agente de suspensão sobre as características das partículas poliméricas obtidas. As microesferas foram caracterizadas quanto ao seu aspecto morfológico, à estabilidade térmica, à incorporação de material magnético e quanto às suas propriedades magnéticas. A quantidade de partículas de ferro incorporadas foi afetada pela velocidade de agitação durante a síntese, pelo teor de material magnético adicionado, pela fase de dispersão do material magnético e pelo teor de monômeros no copolímero. A estabilidade térmica dos copolímeros foi afetada, principalmente, pelo teor de material magnético incorporado e pelo teor de monômeros, levando em consideração resinas com a mesma quantidade de material magnético adicionado. A magnetização de saturação para as microesferas foi afetada pelo teor de material magnético incorporado. A modificação da superfície da magnetita com ácido oleico foi considerada importante para a incorporação do material magnético na matriz do copolímero.Partículas poliméricas magnéticas com comportamento superparamagnéticos foram obtidas com morfologia esférica e magnetização de saturação de 7,11 (emu/g), utilizando razão molar de monômeros de 50/50 %, 1 % de PVA, 20 % de magnetita modificada com ácido oleico adicionada à fase orgânica e velocidade de agitação mecânica de 500 rpm / In this dissertation, polymeric microspheres with magnetic properties based on glycidyl methacrylate and divinylbenzene were synthesized by suspension polymerization technique. In order to obtain magnetic properties, magnetite particles modified by oleic acid were synthesized in laboratory. The effects of stirring rate, concentration of crosslink, the concentration of magnetite added and the concentration of stabilizer on the particles properties were studied. The magnetic microspheres were characterized according their morphology, thermal stability, incorporation of magnetite and their magnetic properties. The incorporate of iron particles content was mainly affected by stirring rate during the synthesis, by the content of magnetic material added, by the dispersion phase of magnetic material and by the monomers content in the copolymer. The thermal stability of copolymers was mainly affected by the content of magnetic material incorporated and by the monomers content, taking in account the resins with the same content of magnetic material added. The saturation magnetization for the microspheres was effected by the content of magnetic material incorporated. The modification with oleic acid was considered important to the incorporation of the magnetic material in the copolymer matrix.Magnetic polymeric particles with superparamagnetic behavior have been obtained with spherical morphology and saturation magnetization of 7.11 (emu/g). It was used monomers molar ratio of 50/50 %, 1% PVA, 20 % magnetite particles modified by oleic acid dispersion on organic phase and stirring rate of 500 rpm during the synthesis
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Encapsula??o de nanopart?culas de magnetita em matriz de poli(metacrilato de metilaco?cido metacr?lico) por processo de polimeriza??o em miniemuls?oNunes, Juliana de Souza 18 October 2007 (has links)
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Previous issue date: 2007-10-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Magnetic particles are systems with potential use in drug delivery systems, ferrofluids, and effluent treatment. In many situations, such as in biomedical applications, it is necessary to cover magnetic particles with an organic material, as polymers. In this work, magnetic particles were obtained through covering magnetite particles with poly(methyl methacrylate‐comethacrylic acid) via miniemulsion polymerization process. The resultant materials were characterized X‐ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), zeta potential (��) measurements and vibrating sample magnetometry (VSM). XRD results showed magnetite as the predominant cristalline phase in all samples and that cristallites had nanometric dimensions. Thermogravimetric analysis revealed an increase in polymer thermal stability as a result of magnetite encapsulation. TGA results showed also that the encapsulation efficiency was directly related to nanoparticles s hidrofobicity degree. VSM measurements showed that magnetic polymeric particles were superparamagnetic, so that they may be potentially used for magnetic (bio)separation / Part?culas magn?ticas s?o sistemas com potencial de uso em libera??o controlada f?rmacos, ferrofluidos e tratamentos de efluentes. Em muitas situa??es, como em aplica??es biol?gicas, ? necess?rio revestir as part?culas magn?ticas com um material org?nico, como pol?meros. Neste trabalho, part?culas magn?ticas foram obtidas pelo revestimento de part?culas de magnetita por poli(metacrilato de metila‐co?cido
metacr?lico) via processo de polimeriza??o em miniemuls?o. Os produtos obtidos foram caracterizados por difra??o de raios X (DRX), espectroscopia de absor??o no infravermelho por transformada de Fourier (FTIR), an?lise termogravim?trica (TG), medidas de potencial zeta (��) e magnetometria de amostra vibrante (MAV). Os resultados de DRX mostraram que a magnetita ? a fase cristalina dominante em todas as amostras, tendo seus cristalitos dimens?es nanom?tricas. A an?lise termogravim?trica revelou um aumento na estabilidade t?rmica das amostras com magnetita encapsulada e que a efici?ncia de encapsula??o foi diretamente relacionada ao grau de hidrofobiza??o das nanopart?culas. Medidas de magnetiza??o mostraram que as part?culas polim?ricas magn?ticas foram superparamagn?ticas, podendo ser satisfatoriamente utilizadas em processos de (bio)separa??o magn?tica
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Chemistry and Corrosion Mechanisms of Steels Embedded in High-density Slag Concrete for Storage of Used Nuclear FuelNadarajah, Parthiban 15 December 2011 (has links)
The chemistry and corrosion mechanisms associated with reduced sulfur compounds such as calcium sulfide, present in ground granulated blast-furnace slag (GGBFS), have been studied in high-density concrete, mortar and simulated pore-water environments. The high-density concrete and mortar samples were produced to replicate the high-density GGBFS concrete, in the dry storage containers (DSCs), used for radiation shielding from used nuclear fuel. Electrochemical measurements on embedded steel electrodes in high-density GGBFS concrete and mortar samples, showed that sulfide is capable of consuming oxygen to create a stable, reducing environment, though not in all cases, and the high-frequency electrolyte resistance increases with hydration time. Ion chromatography on simulated pore-water environments determined that thiosulfate is quite kinetically stable as a sulfide oxidation product and magnetite is capable of oxidizing sulfide. Microscopy has also been used to provide visual evidence of GGBFS hydration and elemental quantification of the hydrating microstructure in different environments.
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Chemistry and Corrosion Mechanisms of Steels Embedded in High-density Slag Concrete for Storage of Used Nuclear FuelNadarajah, Parthiban 15 December 2011 (has links)
The chemistry and corrosion mechanisms associated with reduced sulfur compounds such as calcium sulfide, present in ground granulated blast-furnace slag (GGBFS), have been studied in high-density concrete, mortar and simulated pore-water environments. The high-density concrete and mortar samples were produced to replicate the high-density GGBFS concrete, in the dry storage containers (DSCs), used for radiation shielding from used nuclear fuel. Electrochemical measurements on embedded steel electrodes in high-density GGBFS concrete and mortar samples, showed that sulfide is capable of consuming oxygen to create a stable, reducing environment, though not in all cases, and the high-frequency electrolyte resistance increases with hydration time. Ion chromatography on simulated pore-water environments determined that thiosulfate is quite kinetically stable as a sulfide oxidation product and magnetite is capable of oxidizing sulfide. Microscopy has also been used to provide visual evidence of GGBFS hydration and elemental quantification of the hydrating microstructure in different environments.
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周期的断続磁場を用いた磁気クロマトグラフィーの開発野水, 勉, 田中, 智一 03 1900 (has links)
科学研究費補助金 研究種目:基盤研究(C)(2) 課題番号:09640721 研究代表者:野水 勉 研究期間:1997-1998年度
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