ANDRADE NETO, Davino Machado. Magnetic ressonance imaging contrast agents obtained by fast sonochemistry approach. 2016. 84 f. Dissertação (Mestrado em Química)-Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Aline Mendes (alinemendes.ufc@gmail.com) on 2017-01-25T19:35:32Z No. of bitstreams: 1 2016_dis_dmandradeneto.pdf: 4658452 bytes, checksum: 4d05fbe6bccc67518a89306c468793a6 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-01-26T20:28:31Z (GMT) No. of bitstreams: 1 2016_dis_dmandradeneto.pdf: 4658452 bytes, checksum: 4d05fbe6bccc67518a89306c468793a6 (MD5) / Made available in DSpace on 2017-01-26T20:28:31Z (GMT). No. of bitstreams: 1 2016_dis_dmandradeneto.pdf: 4658452 bytes, checksum: 4d05fbe6bccc67518a89306c468793a6 (MD5) Previous issue date: 2016 / Functionalized Fe3O4 nanoparticles (NPs) have emerged as a promising contrast agent for magnetic resonance imaging (MRI). Their synthesis and functionalization methodology strongly affects their performance in vivo. Although thermal decomposition is the most commonly used growth methodology reported in the literature, it has proven to be time-consuming, expensive, and laborious. Therefore, this work describes a rapid and facile sonochemical methodology to synthesize and functionalize Fe3O4 NPs with excellent physico-chemical properties for MRI. In this work, a sonochemistry approach was used to produce, in 12 min, Fe3O4 NPs functionalized with polysodium acrylate (PAANa), trisodium citrate (CIT), branched polyethylenimine (BPEI), and sodium oleate. X-ray diffraction and transmission electron microscopy demonstrated that the NPs were composed of a single inverse spinel phase with an average diameter of 9–11 nm and a narrow size distribution. It was confirmed by Mössbauer spectroscopy and magnetic measurements that the obtained NPs were transitioning to the superparamagnetic regime and possessed excellent magnetization saturation values (59–77 emu/g). Fourier transform infrared spectroscopy proved that the sonochemistry approach provided conditions that induced a strong interaction between Fe3O4 and the capping agents. Furthermore, dynamic light scattering experiments evidenced that samples coated with PAANa, CIT, and BPEI possess colloidal stability in aqueous solvents. Emphasis must be placed on PAANa-coated NPs, which also presented remarkable colloidal stability under simulated physiological conditions. Finally, the obtained NPs exhibited great potential to be applied as an MRI contrast agent. The transverse relaxativity values of the NPs synthesized in this work (277–439 mM-1s-1) were greater than those of commercial NPs and those prepared using other methodologies. Therefore, this work represents significant progress in the preparation of Fe3O4 NPs, providing a method to prepare high-quality materials in a rapid, cost-effective, and facile manner. / Nanopartículas (NPs) funcionalizadas emergiram como promissores candidatos para serem aplicadas como agente de contraste para imagem por ressonância magnética nuclear e sua metodologia de síntese e funcionalização afetam fortemente sua performance in vivo. A metodologia mais utilizada para a produção dessas NPs funcionalizadas é a decomposição térmica, a qual tem provado ser financeiramente desfavorável, laboriosa além de requisitar longos tempos de execução. Portanto, este trabalho tem como objetivo descrever uma metodologia fácil e rápida, através do método sonoquímico, para a síntese e funcionalização de NPs de Fe3O4 com excelentes propriedades físico-químicas com objetivo de serem aplicadas como agente de contraste para imagem por ressonância magnética nuclear. Neste trabalho, o método sonoquímico foi usado para produzir, em 12 min, NPs de Fe3O4 funcionalizadas com policrilato de sódio, citrato de sódio, polietilenamina ramificada e oleato de sódio. Difração de raios-X e microscopia eletrônica de transmissão demonstraram que as NPs produzidas são compostas de uma única fase de espinélio inverso de 9-11 nm de diâmetro e uma distribuição de tamanho estreita. Foi confirmado por meio da espectroscopia Mössbauer e medidas magnéticas que as NPs sintetizadas estão em transição para o regime superparamagnético e que possuem excelente valor de magnetização de saturação (59-77 emu/g) para aplicações biomédicas. Espectroscopia de infravermelho por transformada de Fourier provou que a radiação sonoquímica forneceu condições adequadas para que acontecesse uma interação forte entre o núcleo magnéticos e os agentes fucionalizantes. Além disso, experimentos de espalhamento dinâmico de luz confirmaras que as amostras recobertas com moléculas orgânicas hidrofílicas possuem estabilidade coloidal em solventes aquosos. Destaque deve ser dado a nanopartícula magnética recoberta com poliacrilato de sódio, que demonstrou excelente estabilidade coloidal em condições fisiológicas simuladas. Finalmente, as NPs obtidas se mostraram serem promissores candidatos a agentes de contraste. Uma vez que seus valores de relaxatividade transversal foram maiores que os agentes de contraste comerciais e daqueles preparados por outras metodologias sintéticas. Portanto, este trabalho trás um grande avanço no que se refere a preparação de NPs de Fe3O4 funcionalizadas para aplicações biológicas, uma vez que materiais de alta qualidade foram preparados de forma rápida e fácil.

The Sonochemistry Centre at Coventry University is one of a group of organisations working on a project to develop a new technology for producing antimicrobial textiles. This technology involves the use of an ultrasonic process (sonochemical) to generate and impregnate fabrics with antibacterial metal oxide nanoparticles. The expectation is that these textiles can be produced at an affordable price for routine use in hospitals as uniforms, curtains, hospital bed sheets and linen. The aim of this PhD project was to assess the antibacterial activity of fabrics impregnated with ZnO and CuO NPs against a variety of Gram positive and Gram negative bacteria. The testing was principally carried out according to the absorption method from ISO 20743:2007. Research was also extended to compare different methods of assessing antibacterial activity of textile fabrics. These included disc diffusion tests and shake flask tests in saline or nutrient broth. Overall the results from absorption tests demonstrated that both the ZnO and CuO impregnated fabrics showed very good levels of antibacterial activity (A>2) against the test bacteria (Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa). During the optimisation of lab scale process to the pilot scale, two different types of CuO fabrics were produced to test and compare the antibacterial activity. One type of fabrics were impregnated with pre-made CuO nanoparticles by a ‘throwing the stones’ technology termed TTS and the other with sonochemically formed nanoparticles (in-situ), same as the lab process. The results indicated that the fabrics impregnated with sonochemically formed NPs displayed better antibacterial activity than the pre-made NPs. Leaching of the antibacterial agents in to saline was investigated using a shake flask method. CuO and ZnO coated fabrics prepared at laboratory scale were tested against Staphylococcus aureus, Acinetobacter baumannii and Escherichia coli. It was found that leachates prepared by shaking the fabrics in saline for 3 hours showed no antibacterial activity for CuO fabrics. However, leachates from ZnO fabrics showed an excellent activity after 24 ± 3 hours against all three bacterial species. Flow cytometry (FC) was investigated as an alternative to standard agar plate count (PC) methods for the determination of viable cell numbers. There was a general agreement between the results from agar plate counts and flow cytometry except that post incubation counts were greater with FC. The higher numbers of viable cells detected with FC may have been due to the presence of viable but not culturable cells (VBNC). Viable cells were observed by fluorescence microscopy in post incubation samples in which no viable cells were detected on nutrient agar plates. Cytotoxicity studies were conducted on ZnO and CuO fabrics from the pilot scale (both in-situ and TTS) against human dermal fibroblast cells (HDF) and human hepatocellular carcinoma cells (HepG2) using a MTT assay to determine cell viability. The results showed that ZnO and CuO are not toxic to HDF cells. However, cytotoxicity was seen in HepG2 cells with cell viability decreasing by > 14% for all the fabrics after 24 hours.

Dans le cadre du programme nucléaire français, le combustible des réacteurs est constitué d'oxydes d'uranium ou d'oxydes mixtes d'uranium et de plutonium (appelé MOX). Des développements sont constamment effectués sur les procédés de retraitement de ces combustibles afin d'optimiser la récupération des matières valorisables et de minimiser le volume des déchets. Lors de la dissolution des MOX, la quantité de fines de dissolution résiduelles riches en Pu est parfois importante malgré l'utilisation de conditions chimiques dures (oxydantes et corrosives). La difficulté à dissoudre des lots de PuO2 déclarés non conformes lors de la fabrication du MOX peut également représenter un verrou technologique. Dans ce contexte, la sonochimie est envisagée comme alternative aux méthodes actuelles de dissolution de PuO2, ou de MOX enrichi en Pu. Dans un premier temps, des travaux de dissolution sonochimique ont été réalisés sur un analogue inactif de PuO2, à savoir CeO2. Les résultats obtenus ont ainsi permis d'orienter les expériences de dissolution de PuO2. En conditions réductrices et acides, beaucoup plus douces que celles utilisées industriellement, la dissolution totale de ces deux oxydes a été effectuée en quelques heures. Parallèlement, une étude connexe a montré qu'il est possible de dissoudre totalement des oxydes mixtes de lanthanides à base de Ce, par un procédé de dissolution sonocatalytique et réductrice en présence de nanoparticules de Pt. La dissolution est d'autant plus rapide que la teneur en lanthanides trivalents est importante au sein de l'oxyde. Enfin, une dernière partie a été consacrée à la dissolution sous agitation magnétique d'oxydes à base de Ce en présence ou non de métaux nobles, dans des milieux faiblement acides contenant des molécules naturelles réductrices. Dans ces conditions, une dissolution totale, rapide et sélective de ces oxydes a été observée. Ces deux dernières études présentent un intérêt dépassant le cadre du nucléaire et applicable au recyclage de matériaux industriels (pots catalytiques, piles à combustible…). / In the French nuclear program, the reactor fuel consists of uranium oxides or uranium plutonium mixed oxides (called MOX). Developments are constantly made on the resulting reprocessing of these fuels in order to optimize the recovery of reusable materials and to minimize the waste volume. In the case of MOX dissolution, the amount of Pu-rich dissolution residues is sometimes high despite the use of hard chemical conditions (oxidizing and corrosive). The difficulty to dissolve PuO2 batches declared non-standard during the fabrication of MOX can also be a technological barrier. In this context, sonochemistry can be considered as an alternative to current methods of dissolution of PuO2 or Pu enriched MOX. First, experiments of sonochemical dissolution were performed on an inactive analogue of PuO2, namely CeO2. The results were then used as a working basis for the dissolution of PuO2. Under reducing and acidic conditions, much milder than those used industrially, the complete dissolution of these two oxides was carried out within a few hours. Meanwhile, a related study showed that it is possible to completely dissolve lanthanide mixed oxides by a process of sonocatalytic and reductive dissolution in the presence of Pt. The dissolution rates increase with the trivalent lanthanide content within the oxide. Finally, the last part was devoted to the dissolution under magnetic stirring of Ce-based oxides in the presence or absence of noble metals, in weakly acidic media containing reducing natural molecules. Under these conditions, a complete, rapid and selective dissolution of these oxides was observed. These last two studies present an interest beyond the scope of nuclear chemistry, concerning the recycling of industrial materials (catalytic converters, fuel cells...).

No description available.

Ultrasonic humidifiers use sound vibrations at frequencies higher than can be heard by humans (> 20,000 Hz) to generate aerosolized water also have potential for inducing sonochemical reactions for chemicals present in water. This research focuses on examining oxidants formed within ultrasonic humidifiers, as well as the oxidants effects of contaminants in water used in the systems. Hydroxyl radicals were found using DMPO as a spin trap. Caffeine and 17β-estradiol, as pharmaceutical contaminants of drinking water, were both emitted from the humidifier when present in the water reservoir and would enter breathing air. Emitted 17β-estradiol was found at 60% of the initial concentration filled in the ultrasonic humidifier after 480 minutes. Caffeine exhibited less degradation than 17β-estradiol. Degradation of both pharmaceuticals was attributed to ultrasonic processes, most likely oxidation with hydroxyl radicals produced. Bromide as a contaminant of the fill water was found to remain constant over time. / MS

Os meios confinados restringirem o grau de liberdade dos reagentes e podem afetar significativamente seus estados energéticos e perfis de coordenada de reação. Macrociclos são muito utilizados nessa perspectiva graças a capacidade de hospedar moléculas em suas cavidades e modificar o momento de dipolo das mesmas. Isso permite que estes cavitandos sejam usados como catalisadores, sensores ou simples carreadores, por exemplo. A bambus[6]urila (BU[6]), sintetizada recentemente, ganhou atenção graças à sua capacidade de formar caviplexos estáveis com ânions. Os reagentes de partida são glioxal e ureia, compostos relativamente baratos e comuns, mas a rota síntetica descrita na literatura, no entanto, não contém uma série de informações importantes, o que dificulta a síntese da BU[6]. Muitos estudos computacionais foram realizados para prever e entender as interações deste macrociclo com outras moléculas. No entanto, informações relevantes sobre a BU[6] como a estabilidade térmica, capacidade de complexar cátions ou solubilidade em soluções salinas e solventes comuns, ainda não foram publicados. Nesse trabalho foram determinadas as propriedades fundamentais (densidade, condutividade elétrica e pH de solução saturada, ponto de fusão) da BU[6] vazia e de seu caviplexo BU[6]HCl, bem como a estabilidade térmica das mesmas por meio de análises termogravimétricas. Além disso, tentamos reduzir o tempo de síntese BU[6]HCl utilizando ultrassom e os produtos obtidos foram analisados por técnicas espectrométricas e espectroscópicas. A solubilidade da BU[6]HCl foi estudada utilizando diversos solventes, soluções salinas de metais alcalinos e alcalino-terrosos e meios com diferente acidez. Titulações condutimétricas de soluções de BU[6]HCl com soluções salinas de metais alcalinos e alcalino-terrosos foram realizadas para avaliar a interação entre a BU[6] e os cátions. Por fim, foram realizados experimentos para avaliar a interação dos gases bromo e iodo com as BU[6] vazia e BU[6]HCl, em estado sólido, e os produtos obtidos submetidos à analises espectroscópicas e espectrométricas. / Confined media restrain degrees of freedom and can affect considerably their energetic states and reaction coordinate profiles. Macrocycles are widely used for such purpose thanks to their capacity to include molecules in their cavities, changing their eletric dipole moments. This is why they can be used as calalyst, sensors or simple carriers for example. Bambus[6]uril (BU[6]), recently synthesized, has drawn attention due to its ability to form stable caviplexs with anions. The starting reagents are glyoxal and urea, two afordable and common compounds, but the synthetic route described in the literature however, lacks many important information make it difficult to prepare BU[6]. Many computer calculations were done to preview and understand the interactions between this macrocycle and other molecules. However, relevantly informations about BU[6], such as thermal stability, its ability to complex cations or its solubility in salt solutions and common solvents were not published yet. In this work the fundamental properties (density, pH and conduvity of saturated solution, melting point) of empty BU[6] and BU[6]HCl has been determined, as well the thermal behaviour of the compounds by thermogravimetric analysis. Beyond that, we have attempted to reduce BU[6]HCl synthesis time using ultrasound and the obtained products were analyzed by spectrometric and spectroscopic techniques. The solubility of BU[6]HCl has been studied with diversal solvents, alkaline and alkaline earth metals saline solutions and different acidity media. Condutimetric titrations of BU[6]HCl with alkaline and alkaline earth metals saline solutions were realized to evaluate the interaction of BU[6] and cations. Lastly, experiments to evaluate the interaction between the gases bromine and iodine with empty BU[6] and BU[6]HCl, in solid state, were realized and the obtained products submitted to spectroscopic and spectrometric analysis.

Zhang Lizhi. / "July 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Le démantèlement des réacteurs UNGG produit un grand volume de matériaux métalliques contaminés. Parmi ceux-ci, les alliages à base de magnésium, connus comme métaux hautement réactifs, présentent un risque élevé de corrosion et peuvent générer de l'hydrogène gazeux qui peut causer de graves dommages pendant le stockage. Afin de réduire le volume des effluents radioactifs générés et de déclasser les déchets nucléaires, la sonochimie peut être mise en œuvre comme technologie efficace pour la décontamination des surfaces métalliques. La sonochimie traite des effets des ondes ultrasonores sur les réactions chimiques en solution. Les effets observés en sonochimie proviennent du phénomène de cavitation acoustique, qui est la nucléation, la croissance et l'effondrement implosif rapide de microbulles remplies de gaz et de vapeur. Des espèces et des radicaux excités peuvent être générés dans le plasma formé, qui émet de la lumière (sonoluminescence). Lorsque l’effondrement des bulles a lieu à proximité d'une surface solide, il produit des ondes de choc violentes et des microjets dirigés vers la surface. Ces effets physiques contribuent fortement au nettoyage par ultrasons, à la dépassivation de surfaces et à la décontamination.Cette étude se concentre sur : 1) les comportements de cavitation près d'une surface solide ; 2) la structuration ultrasonore des surfaces étendues de magnésium ; 3) la décontamination par ultrasons de surfaces métalliques radioactives. L'activité sonochimique est évaluée en mesurant les rendements en H2O2, la distribution de sonochimiluminescence et les spectres de sonoluminescence. Les effets de la structuration et de la décontamination des surfaces sont suivis au moyen de MEB, EDS, FTIR, Raman, DRX, analyse du comportement de mouillage, spectrométrie de masse et ICP-AES.Ce travail a mis en évidence le fort impact de la fréquence ultrasonore sur l'activité sonochimique, sa distribution spatiale et sur les effets générés sur les échantillons de magnésium. Une répartition spatiale homogène de l'activité sonochimique est observée aux fréquences ≥ 100 kHz. L'effondrement asymétrique des bulles est plus susceptible de se produire près de la surface solide aux ultrasons à haute fréquence. La formation d’une structure allongée semblable à une balle de golf est observée à des fréquences comprises entre 100 et 362 kHz. De telles architectures résultent de la dissolution contrôlée par ultrasons de la surface Mg. Il est probable que la nucléation hétérogène assurée par la création de défauts par les ultrasons et la libération de gaz H2 soient à l'origine de la formation des cratères. La décontamination des surfaces radioactives de Mg et d’alliages de Mg ont d'abord démontré un nettoyage rapide par les ultrasons suivi d’un lent processus de recontamination due à l'adsorption de brucite formée sur les surfaces de Mg ou de ses alliages. / The dismantling of UNGG reactors produces large volumes of contaminated metallic materials. Among these, magnesium-based alloys which are known as highly reactive metals, have a high risk of corrosion and can generate hydrogen gas that can cause serious damages during storage. In order to reduce the volume of generated radioactive effluents and downgrade nuclear wastes, sonochemistry can be applied as an efficient technology for metallic surface decontamination. Sonochemistry deals with the effects of ultrasound waves on chemical reactions in solution. The effects observed in sonochemistry originate from the acoustic cavitation phenomenon, which is the nucleation, growth and rapid implosive collapse of gas and vapor filled microbubbles. Excited species and radicals can be generated in the formed plasma and light (sonoluminescence) is emitted. When the bubble collapse takes place in the vicinity of a solid surface, it produces violent shock waves and microjets directed towards the surface. These physical effects strongly contribute in ultrasonic cleaning, surface depassivation and decontamination.This study focuses on: 1) the cavitation behaviors near a solid surface; 2) the ultrasonic structuration of extended magnesium surfaces; 3) the ultrasonic decontamination of radioactive metal surfaces. The sonochemical activity is evaluated by measuring H2O2 yields, sonochemiluminescence distribution and sonoluminescence spectra. Surface structuration and decontamination effects are followed by means of SEM, EDS, FTIR, Raman, XRD, wetting behavior analysis, mass spectrometry and ICP-AES.The investigations reveal a strong ultrasonic frequency dependency of the cavitation activity and distribution and of the effects generated on the Mg samples. A homogeneous spatial repartition of sonochemical activity is observed at frequencies ≥ 100 kHz. Asymmetrical bubble collapse is found more likely to happen near the solid surface at high frequency ultrasound. A golf-ball like extended structure is observed at frequencies between 100 and 362 kHz. It is shown that such architectures result from the ultrasonically controlled dissolution of the Mg surface. Heterogeneous nucleation provided by the creation of defects by ultrasound and the release of H2 gas are supposed to be at the origin of the crater formation. Decontamination of radioactive surfaces of Mg and Mg alloys demonstrate rapid ultrasonic cleaning followed by a slow recontamination process which is due to the adsorption of brucite formed on the surfaces of Mg or its alloys.

The dissolution of quantum sized CdS and MnO2 particles in water was conducted using 20 kHz ultrasound. CdS particles were found to dissolve chemically via an oxidation process while MnO2 particles dissolved via a reductive process. It was found that the dissolution of the colloids could be controlled via the addition of surface active chemicals to solution and by varying the saturation gas type. In the presence of Na2S or propan-2-ol and argon gas, the dissolution of CdS was inhibited, whereas the addition of alcohols (methanol, ethanol, propan-2-ol, butan-1-ol and pentan-1-ol) to the MnO2 system led to an increase in the amount of dissolution for a given time of sonication. This increase in dissolution was found to be dependent on the ability of the surface active radical scavenger to accumulate around the bubble interface during the cavitation process. Eventually, at higher alcohol concentration there was a plateau or a limiting value reached for the efficiency of colloid dissolution which was common for each alcohol. (For complete abstract open document)

Thesis (M.Phil.) - University of Queensland, 2005. / Includes bibliography.