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1
IMPALLARIA, Anna. "Radiographic imaging of chemical elements for Cultural Heritage." Doctoral thesis, Università degli studi di Ferrara, 2017. http://hdl.handle.net/11392/2487963.
Full textAbstract:
Radiographic techniques, usually, don’t give information about the chemical composition of a sample. However, thanks to the K-edge differential technique, it is possible to highlight the presence of target chemical elements with the radiography.
This technique takes advantage on the K-edge discontinuity of the X-rays mass absorption coefficient. Considering a target element and acquiring two radiographies with monochromatic beams under and over the K-edge energy, the main difference between the two images is due to the presence of the element itself.
To apply this peculiar radiographic technique, using the traditional X-ray tubes, two ways are possible:
1. Monochromatizing the beam coming out through the Bragg diffraction and acquiring the two radiographic images at the energies under and over the K-edge of the target;
2. For a target element with atomic number Z, using a set of three filters of the elements Z, Z+1 and Z-1, acquiring three different radiographies that, after the digital subtraction, would give images similar to the ones obtained with monochromatic beams.
Both the two techniques have been employed in Ferrara, giving attention to the development of portable instruments, thus to promote their application in situ. For the first, the work of the thesis has been focused on the implementation of a new goniometric set-up, in respect of the existing one, and on the alignment of all the components (X-ray tube, Bragg diffraction crystal and detectors). For the second, the research has mainly regarded the use of balanced filters on canvas mock-ups painted with cadmium, copper and cobalt based pigments and their superimposition with other ones. The filters has been tested using the radiographic scanning systems developed in Ferrara.
The new radiographic scanner for in situ application has been designed, realized and tested in the PhD period. Its reduced dimensions have allowed its use also on a big dimension painting (195 x 154 cm) in the Gallery of Palazzo Bellomo in Siracuse.Tipicamente le tecniche radiografiche non permettono di ottenere informazioni riguardanti gli elementi chimici presenti in un campione. Tuttavia, grazie alla tecnica differenziale al K-edge, anche tramite la radiografia è possibile evidenziare la presenza di elementi chimici bersaglio. La tecnica sfrutta la discontinuità del K-edge nel coefficiente di assorbimento di massa dei raggi X. Considerando un elemento target e acquisendo due radiografie con fasci monocromatici di energia sotto e sopra il K-edge, la maggiore differenza tra le due immagini sarà dovuta alla presenza dell’elemento stesso. Per effettuare questa particolare tecnica radiografica, sfruttando i classici tubi a raggi X, si possono percorrere due vie: 1. monocromatizzare il fascio uscente tramite diffrazione di Bragg e acquisire le due immagini radiografiche alle energie sopra e sotto il K-edge del target; 2. per un elemento bersaglio di numero atomico Z, usare un set di tre filtri degli elementi Z, Z+1 e Z-1, acquisendo tre radiografie diverse che, dopo sottrazione digitale, daranno immagini simili a quelle ottenute con i fasci monocromatici. Entrambe le tecniche sono state impiegate a Ferrara, ponendo particolare attenzione allo sviluppo di strumenti portatili, così da favorirne la loro applicazione in situ. Per la prima, il lavoro di tesi si è concentrato sull’implementazione di un sistema goniometrico rispetto a quello esistente e sull’allineamento di tutte le sue parti (tubo a raggi X, cristallo per la diffrazione di Bragg e rivelatori). Per la seconda, la ricerca ha riguardato maggiormente l’applicazione dei filtri bilanciati a provini su tela di pigmenti a base di cadmio, rame e cobalto e della loro sovrapposizione con altri pigmenti. I filtri sono stati testati impiegando i sistemi a scansione per le radiografie sviluppati a Ferrara. Il nuovo scanner radiografico per le applicazioni in situ è stato progettato, realizzato e testato durante questo lavoro di tesi. Le sue ridotte dimensioni, ne hanno consentito l’applicazione anche su un dipinto di grandi dimensioni (195 x 154 cm) nella Galleria di Palazzo Bellomo di Siracusa.
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Sides, Jonathan David. "Scientific Realism and the Periodic Table of Chemical Elements." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/43909.
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The periodic table poses a difficulty for both scientific realists and anti-realists. The antirealist
has difficulty accounting for the success of the table during a period in chemistry
when many theories and concepts changed; the spatial relations of current tables in use do
not show fundamental changes from the original tables proposed by Mendeleev. Yet,
most versions of scientific realism are based upon the understanding that theories are
some collection of written propositions or equations. The table as an image successfully
functions very much like a theory: it is an organization of known facts, has been used to
make predictions, and is plastic enough to accommodate unforeseen novel facts.
Assuming the truth of the representational relations between the table and the world
poses interesting issues for the realist. Ian Hacking's entity realism and the structural
realism of several philosophers are both possible versions of scientific realism that fail to
account for the table. Hacking's version fails in this case because the role of
representation is central to understanding the history of the table; structural realism fails
because it diminishes to much the role that first order properties have as they relate to the
formulation of the second order relationships that comprise the table. Philip Kitcher of
Science, Truth, and Democracy leaves himself open to two interpretations about the
metaphysics of pluralism. One of these is indefensible; the other is quite well supported
by the plurality of successful periodic tables.Master of Arts
3
Kuhn, Kirsti. "A study of the coordination behaviour of the lanthanide series with oxygen-donor ligands." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1009533.
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The reactions between the lanthanide nitrate salts and the ligand triphenylphosphine oxide (TPPO) gave rise to nine-coordinated complexes of the nature Ln(TPPO)3(NO3)3, for Ln = La – Dy, Er, Tm, in which the Ln(III) centre is coordinated to three phosphoryl oxygen atoms and three bidentate nitrate ligands. Generally, the geometry can be described as being mer-octahedral, where the nitrate ligands are considered as monoatomic species. The product of the reaction between Yb(NO3)3·5H2O and TPPO, however, was a highly symmetrical eight-coordinated complex, in which the Yb(III) centre was coordinated to two bidentate nitrate groups and four TPPO molecules. The geometry in this case is best described as being trans-octahedral, with the two nitrate ligands coordinated practically perpendicular to one another. The complexes isolated from the reactions of lanthanide nitrate salts with the ligand bis(pentamethylene)urea (PMU) had the general formula Ln(PMU)3(NO3)3, where Ln = La – Dy, Yb, Lu. The complexes were found to be nine-coordinated with distorted trigonal prismatic geometry, in which the one base of the prism is composed of the oxygen atoms of the three PMU ligands and the other base is made up by one oxygen atom from each of the bidentate nitrate groups. The second oxygen atoms of each of the nitrate groups protrude upward, occupying capping positions. The reactions of the La and Pr nitrate salts with the ligand 2,2’-dipyridyl-N,N’-dioxide (DPDO) produced two novel complexes of the nature [Ln(DPDO)(H2O)2(NO3)3]. These complexes are remarkable in that their crystal structures reveal the Ln(III) centres to be ten-coordinated. The geometry around the Ln(III) centres was complex, due to the presence of a seven-membered chelate ring, formed by the bidentate coordination of the oxygen atoms from the DPDO ligands to the metal centres. The chelate ring did not lie in a single plane, but was twisted at the pyridyl bridgeheads to lie above and below the coordination plane.
4
Jally, Bastien. "Expanding Agromining to the Rare-Earth Elements : Key elements of success from a chemical engineering perspective." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0004.
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Pour faire face au défi du changement climatique, de nouvelles technologies ont récemment émergé, permettant l’exploitation ou le stockage d’énergies renouvelables. Des éoliennes aux voitures électriques, des solutions prometteuses apparaissent pour adapter nos modes de vie. Ces technologies ajoutent cependant une pression sur d’autres ressources non renouvelables, parmi lesquelles les terres rares (TR). Ces 16 éléments, constitués des 14 lanthanides, de l’yttrium (Y) et du scandium (Sc), sont au cœur des technologies actuelles. Les technologies de la communication (écrans des smartphones, fibres optiques) et de l’armement (superalliages), aujourd’hui estimées essentielles, accroissent encore la demande pour ce groupe d’éléments, faisant partie de la liste des « matières premières critiques » proposée par l’Union Européenne.Leur extraction lors des dernières décennies a laissé derrière elle un paysage morcelé, notamment dans le Sud de la Chine. Aujourd’hui interdites, les pratiques de décapage puis excavation, suivies d’une lixiviation en tas, ont légué des centaines d’hectares de stériles miniers. Ces milieux dégradés, qui étaient autrefois des forêts tropicales, sont sujets à une érosion intense, et contiennent encore des TR à faible concentration. Dans un contexte où les services écosystémiques des milieux naturels sont plus que jamais indispensables, est apparue la volonté de refonctionnaliser ces sols délaissés. Des aides gouvernementales chinoises ont été déployées pour leur revégétalisation à grande échelle. Des programmes de recherche ont aussi été lancés pour mieux comprendre le fonctionnement de ces écosystèmes dégradés et envisager leur restauration. Dans ce cadre, une des clés de la réussite pourrait être le recours à des plantes adaptées localement, et présentant un intérêt économique, pour la production d’énergie, de fibres, ou la récupération des terres rares présentes dans les stériles. La filière « agromine » est une solution fondée sur la nature, qui combine la culture de plantes hyperaccumulatrices et de la récupération des métaux à partir de ces plantes. Cette filière pourrait être très intéressantes dans ce contexte, puisque les espèces D. linearis L. et P. americana, hyperaccumulateurs de TR sont présentes sur ces anciens sites miniers. Ces plantes concentrent les TR dans leurs partie aériennes, jusqu’à des valeurs supérieures aux minerais exploités.La récupération des TR, via des procédés hydrométallurgiques, permettrait alors de concrétiser la valeur économique de ces plantes, et contribuerait à l’approvisionnement en TR, nécessaire au déploiement des technologies modernes. L’objectif de cette thèse, qui fait suite à celle de Z . Chour (2018, Univ. Lorraine) est de développer et optimiser des procédés de récupération de TR à partir des cendres de D. linearis et de la plante P. americana, qui a des caractéristiques botaniques, et physico-chimiques différentes. Il s’agit aussi d’étudier l’impact environnemental et le coût des différents procédés identifiés. Elle a été menée en co-direction entre l’Université de Lorraine (Nancy, France) et l’Université Sun Yat-sen (Canton, Chine). Ce travail a permis de répondre à des questions scientifiques sur la séparation de TR à faible concentrations dans des matrices riches en silice et contenant aussi de l’aluminium. Il a abouti à la conception et l’optimisation d’un procédé original à partir de D. linearis, accompagné d’une comparaison de différents procédés, au plan des consommation de matière et d’énergie et de la production des déchets, et d’une évaluation économique. Il constitue ainsi une étape essentielle à la fois pour le développement scientifique de la filière agromine et pour sa mise en œuvreTo meet the challenge of climate change, new technologies have recently emerged that allow the use or storage of renewable energy. From wind turbines to electric cars, promising solutions are emerging to adapt our lifestyles. However, these technologies are adding pressure on other non-renewable resources, including rare earth elements (REEs). These 16 elements, made up of the 14 lanthanides, yttrium (Y) and scandium (Sc), are at the heart of current technologies. Communication technologies (smartphone screens, optical fibers) and weapons technologies (superalloys), which are now considered essential, are further increasing the demand for this group of elements, which are on the list of "critical raw materials" proposed by the European Union.Their extraction over the last decades has left behind a fragmented landscape, especially in Southern China. Now banned, the practices of stripping and excavation, followed by heap leaching, have resulted in hundreds of hectares of tailings. These degraded environments, which were once tropical forests, are subject to intense erosion and still contain low concentrations of REEs. In a context where the ecosystem services of natural environments are more essential than ever, the desire to refunctionalize these derelict soils has emerged. Chinese governmental aid has been deployed for their large-scale revegetation. Research programs have also been launched to better understand the functioning of these degraded ecosystems and to consider their restoration.In this context, one of the keys to success could be the use of locally adapted plants that are of economic interest for the production of energy, fibers, or the recovery of rare earths present in the tailings. The "agromining" chain of processes is a nature-based solution, which combines the cultivation of hyperaccumulator plants and the recovery of metals from these plants. This chain could be very interesting in this context, since the species D. linearis L. and P. americana, hyperaccumulators of REEs, are present on these former mining sites. These plants concentrate the REEs in their aerial parts, up to values higher than the exploited ores. The recovery of the REEs, via hydrometallurgical processes, would then make it possible to concretize the economic value of these plants, and would contribute to the supply of REEs, necessary for the deployment of modern technologies.The objective of this thesis, which follows that of Z . Chour (2018, Univ. Lorraine) is to develop and optimize REE recovery processes from the ash of D. linearis and from the plant P. americana, which has different botanical, and physicochemical characteristics. The environmental impact and cost of the different processes identified were also studied. This research was conducted in co-supervision between the University of Lorraine (Nancy, France) and Sun Yat-sen University (Canton, China).This work allowed to answer scientific questions on the separation of REEs at low concentrations in silica-rich matrices also containing aluminium. It led to the design and optimization of an original process using D. linearis, accompanied by a comparison of different processes, in terms of material and energy consumption and waste production, and an economic evaluation. It is thus an essential step both for the scientific development of the agromining process and for its implementation
5
Hultén, Amanda. "Determination of trace elements in thrombocytes by ICP-MS." Thesis, Uppsala universitet, Institutionen för kemi - BMC, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-397392.
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David, Brian T. ""Chemical fingerprinting" of volcanic tephra found in Kansas using trace elements." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1413.
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Du, Toit Adam Jacobus. "Thermodynamic behaviour of sulphur and chlorine as minor elements in metallurgical melts." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/5379.
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Includes bibliographical references (p. 137-147)This thesis is presented on the equilibrium studies that have been carried out on a series of slags, specifically chosen to cover the range of composition and conditions appropriate to the melters of the platinum group metals (PGM) producers of South Africa. New measurements have been made on the ferric to ferrous ration, sulphide capacity as well as the chloride capacity mainly for the PGM melter-type slags.
8
Seames, Wayne Stewart. "The partitioning of trace elements during pulverized coal combustion." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284196.
Full textAbstract:
The environmental impact resulting from the release of trace elements during coal combustion is an important issue for the coal-fired electric utility industry. Trace elements exit the combustor by partitioning between the flue gas and the fly ash particles. A comprehensive study has been conducted to investigate the mechanisms governing the partitioning of trace elements during pulverized coal combustion. The behavior of seven trace elements (arsenic, selenium, antimony, cobalt, cesium, thorium, and cerium) in six pulverized coals were studied under commercially relevant conditions in a well-described laboratory combustion environment. The partitioning of trace elements is governed by the extent of volatilization during combustion, the form of occurrence in the flue gas, and the mechanisms controlling vapor-to-solid phase transformation to fly ash particle surfaces. The most common vapor-to-solid phase partitioning mechanism for semi-volatile trace elements is reaction with active fly ash surfaces. Trace elements that form oxy-anions upon volatilization (e.g. arsenic, selenium, antimony) will react with active calcium and iron cation fly ash surface sites. Trace elements that form simple oxides upon volatilization (e.g. cobalt, cesium) will react with active aluminum oxy-anion fly ash surface sites. The maximum combustion temperature affects the availability of active calcium and iron surface sites but not aluminum sites. Sulfur inhibits the reactivity of oxy-anions with iron surface sites. For coals with high sulfur contents (>1 wt % as SO₂), volatilized trace elements that form oxy-anions will partition by reaction with calcium surface sites if sufficient sites are available. For coals with low sulfur contents, volatilized trace elements that form oxy-anions, will partition by reaction with iron surface sites. Volatilized trace elements that form oxy-anions will not partition by reaction if the coal sulfur content is high and the calcium content is low (<3 wt% as CaO). Transition metals (e.g. cobalt) may form simple oxides, oxy-anions or both upon volatilization. An appreciable fraction of trace elements with limited volatility (e.g. cobalt, thorium, cerium, cesium) will volatilize. These will partition back to the solid phase by homogeneous nucleation or surface reaction depending upon the post-combustion conditions present.
9
Skagerkvist, Mio. "Adsorption of anionic elements to steel slag." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-71048.
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Steel slag is a by-product from steel production and has potential to act as a sorbent for several contaminants. Contaminated water is a global problem and cheap and simple remediation solutions are often sought. The potentials are many to use an industrial residue for water purification purposes e.g. low cost. The absorption efficiency was evaluated for two different steel slags further divided into two grain sizes, <0.9 mm and 0.9-2 mm. Laboratory experiments was conducted for three anionic elements; bromine, chromate and molybdate. Controlled parameters were; time, sorbent amount and sorbate concentration. The sorption was primarily dependent on the grain size and the smaller grain size had a higher sorption of all three tested anionic species. Unfortunately the results are partially affected by the release of the tested elements from the sorbent itself.
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Maley, Iain Joseph. "Structural and chemical studies of compounds containing the heavier main group elements." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/15255.
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The solid-state structures of germane-d4, GeD4 and stannane-d4, SnD4, have been investigated by high resolution powder neutron diffraction. These structures have been compared with those found in the gas-phase. It was found that there are weak intermolecular interaction in the solid-state. These results confirm the findings of an earlier vibrational study which suggested a decrease in molecular symmetry on moving from the gaseous to condensed state. Several examples of a new class of organic chalcogenide donor ligand have been prepared and characterised. These new have been used in preparation of a variety of main group organometallic compounds including examples of mono, di- and tri-substituted compounds. The di- and tri-substituted compounds are the first to be subject structural characterisation by X-ray diffraction and the structures include trigonal bipyramidal geometries around gallium and indium atoms. Use of the in situ crystal growth technique has resulted in the structural characterisation of lead(IV) chloride that confirms the tetrahedral geometry and suggests a non-bonding Pb...Cl contact that lies within the sum of the van der Waals radii. Preliminary investigations of PbCl4 under high pressure indicate a phase change from discrete tetrahedral molecules to a layered structure similar to that of polymeric SnF4. The chemistry of PbCl4 is limited by the instability of the compound, but the loss of Cl2 and reduction to Pb(II) occurs upon reaction with SbCl5, leaving the unusual cation fragment [Pb(MeCN)9]2+. The structure of (Me)3PbCl has been determined by neutron diffraction and showed that the earlier investigations by X-ray analysis had erroneously determined the unit cell. The new data disprove the previous assertion that the Cl-Pb...Cl angle was non-linear and confirms that it is in fact 180°, in common with the structures of (Me)3PbBr and (Me)3PbI.
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Lisovyk, Anhelina, and Olga Yezhova. "Features of the corporate style elements of the company of chemical materials." Thesis, Universitatea Tehnică a Moldovei, 2021. https://er.knutd.edu.ua/handle/123456789/18204.
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The paper presents result of the graphic elements study of the corporate identity of the company’s chemical materials. It is determined that the company, including those which are engaged in the sale and supply of chemical products for various industries, is highly-demanded in the market. Development of the improved design-project variant for printed products during corporate identity presentation of the company is principal for the company’s success. The features of printed products with a pronounced corporate identity were investigated.
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Zdanowicz, Katarzyna [Verfasser]. "Chemical Prestressing of Thin Concrete Elements with Carbon Textile Reinforcement / Katarzyna Zdanowicz." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://d-nb.info/1234148285/34.
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Lee, Hyukjae. "Sintering of boron carbide." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19631.
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Daly, Leo. "Complexation and extraction studies of group 15 elements (M=As, Sb, Bi) with azamacrocycles." Thesis, University of Warwick, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297984.
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Yamashita, Celina Izumi. ""Estudo sobre os constituintes inorgânicos presentes em diferentes espécies da planta medicinal do gênero 'casearia' coletadas em regiões distintas da Mata Atlântica, SP"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-05062007-152847/.
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O uso de plantas medicinais no tratamento de doenças tem aumentado de forma significativa nos últimos anos, bem como as pesquisas sobre a caracterização química destas plantas. Neste estudo, foram determinados os constituintes inorgânicos presentes nas folhas e nos extratos de três espécies da planta do gênero Casearia (C. sylvestris, C. decandra e C. obliqua) coletadas em regiões distintas da Mata Atlântica, SP. As composições elementares dos solos em que estas plantas foram cultivadas também foram determinadas. Tradicionalmente, estas plantas são utilizadas devido às suas propriedades antiinflamatórias, antiácidas, anti-sépticas e cicatrizantes. Além disso, as atividades antiulcerogênicas e antitumorais do gênero Casearia, e sua capacidade de neutralizar venenos de serpentes e abelhas, também tem sido comprovadas cientificamente. A metodologia analítica empregada foi a análise por ativação com nêutrons. Irradiações longas e curtas das amostras e dos padrões foram realizadas utilizando fluxos de nêutrons do reator de pesquisas IEA-R1 do IPEN/CNEN-SP. Nas folhas, o elemento K foi encontrado em níveis de porcentagens, os elementos Ca, Cl, Mg e Na na ordem de mg g-1, Br, Fe, Mn, Rb e Zn em μg g-1 e os elementos As, Co, Cr, Cs, La, Sb, Sc e Se em teores mais baixos, da ordem de ng g-1. Os resultados obtidos nas análises dos extratos indicaram que os mesmos elementos determinados nas folhas de Casearia foram também encontrados em seus respectivos extratos. A comparação das composições elementares das folhas de Casearia sylvestris coletadas em três regiões diferentes da Mata Atlântica mostrou que as concentrações dos elementos encontrados nas plantas dependem da composição dos solos em que elas foram cultivadas. Por outro lado, espécies diferentes do gênero Casearia cultivadas em uma mesma região apresentaram composições elementares similares. Estes resultados mostram a importância da realização de estudos que avaliem as atividades farmacológicas de Casearias cultivadas em diferentes tipos de solos. A qualidade analítica dos resultados foi avaliada pela análise dos materiais de referência certificados NIST 1573a Tomato Leaves, NIST 1515 Apple Leaves, INCT-TL-1 Tea Leaves, IAEA-Soil-7 e USGS W1. Os desvios padrão relativos e os erros relativos obtidos nestas análises indicaram boa precisão e exatidão dos resultados.The use of medicinal plants in the treatment of diseases has increased significantly in the last years, as has research concerning chemical characterization of these plants. In this study, inorganic constituents were determined in leaves and in extracts from three medicinal plant species of the Casearia genus (C. sylvestris, C. decandra and C. obliqua) collected in distinct regions of the Atlantic Forest, SP. The elemental compositions of the soils in which these plants were grown were also determined. Traditionally, these plants are used due to their antiinflamatory, antiacid, antiseptic and cicatrizing properties. The antiulcer and the antitumor activities of the Casearia genus and its capacity to neutralize snake and bee venoms, have also been scientifically confirmed. The analytical methodology used was neutron activation analysis. Long and short irradiation periods of the samples and the standards were carried out at IPENs IEA-R1 nuclear research reactor. In the leaf K was found at the percentage levels, Ca, Cl, Mg and Na at mg g-1 levels and the elements Br, Fe, Mn, Rb and Zn at the μg g-1 levels. As, Co, Cr, Cs, La, Sb, Sc and Se at the ng g-1 levels. Results obtained in the extracts indicated that the same elements present in the leaves are also found in their extracts. The comparison between the inorganic composition of Casearia sylvestris leaves collected from three different regions of the Atlantic Forest showed that the elemental concentrations in the plants leaves varied depending on the place where they were grown. Different Casearia species cultivated in a same region presented similar elemental compositions. Based on these findings it can be concluded that the studies about the pharmacological effect of Casearia genus plants grown in different types of soil are of great importance. The quality of the obtained results was assured by the analyses of the certified reference materials NIST 1573a Tomato Leaves, NIST 1515 Apple Leaves, INCT-TL-1 Tea Leaves, IAEA-Soil-7 and USGS W1. The relative standard deviations and the relative errors obtained in these analyses indicated good precision and accuracy of the results.
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Helsingen, Even Buvarp. "Bioaccumulation of chemical elements in grey seals (Halichoerus grypus) from the Baltic Sea." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14591.
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Concentrations of Ag, As, B, Ba, Bi, Ca, Cd, Ce, Co, Cs, Cu, Dy, Er, Fe, Ga, Ge, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nd, Ni, P, Pb, Pr, Rb, S, Sb, Se, Si, Sm, Sn, Sr, Tb, Th, Tl, V, W, Y, Yb and Zn in the livers of grey seals obtained from stranded, hunted and by-caught animals from the Swedish and Polish Baltic coasts were determined by ICP-MS. Stable isotope analysis of δ13C and δ15N was applied to link chemical element concentrations to feeding preferences (pelagic vs. benthic) and trophic position of the seals, respectively. Isotopic ratios in the seals increased in seals from the north towards the southern Baltic Sea, with markedly higher isotopic signatures in seals inhabiting the Polish coast . Analysis of covariance revealed differences in chemical element concentrations between areas for As, B, Cu, Ni, Rb, Sr, Tl with most of these elements exhibiting higher concentrations in seals from the southern Baltic Sea. Additionally age related differences in concentrations of several trace elements were found. Silver, B, Bi, Cd, Co, Hg, Mo, Sb, Se, Sn, V and Zn and the rare earth elements (REE) were found to increase with age. The role of Se in detoxification of Hg was confirmed by high correlation between these two elements (r = 0.99, p < 0.0001). Significantly higher Se:Hg molar ratio were observed in yearlings compared to juvenile and adult seals . Several other elements also revealed statistically significant interrelationships, especially pronounced for the REEs.
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Asakura, Hiroyuki. "Study of X-ray Absorption Spectroscopy of Heavy Elements and Transient Chemical Species." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/198946.
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Bonetto, Francesca <1983>. "Traceability of foodstuffs by chemical characterization using trace elements (REEs) and isotope ratios." Doctoral thesis, Università Ca' Foscari Venezia, 2014. http://hdl.handle.net/10579/4646.
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Identificare dei markers chimici che permettano di collegare un alimento al territorio di produzione o ad una particolare lavorazione, è di primaria importanza. C’è, infatti, un interesse crescente da parte dei produttori e dei consumatori nel settore dell’autenticazione alimentare.
La ricerca effettuata nei tre anni di dottorato è stata finalizzata alla messa a punto di metodiche di spettrometria di massa per l’analisi di elementi in traccia (con particolare interesse per le terre rare) degli isotopi dello stronzio.
Le metodiche analitiche sviluppate sono state applicate a campioni alimentari (formaggio e cereali).
Gli studi di provenienza sono stati approfonditi mediante tecniche statistiche e chemiometriche, che hanno messo in luce caratteristiche chimiche che possono essere fatte risalire all’ambiente di produzione o alle tecniche di lavorazione dei prodotti.
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Roberson, Joshua. "Abrasive waterjet damage of silicon wafers." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/18960.
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Johnson, Andrea. "Sol-gel encapsulation of heterocyclic ligands for aqueous sensing applications." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307510.
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Nakashima, Kazuko. "Differentiation, distribution and chemical state of intracellular trace elements in LAD2 mast cell line." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/137044.
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Siddique, Pasley Rehana. "The physical and chemical reclamation and recycling of elements from black aluminium furnace residues." Thesis, Brunel University, 2003. http://bura.brunel.ac.uk/handle/2438/7272.
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Dross is the inevitable waste product generated by the world-wide primary and secondary aluminium industries. Around 3.5 million tonnes of white dross and 0.85 million tonnes of black dross are produced per year. Drosses are classified depending on metal content. White dross contains 40% and black dross contains 10% of aluminium. About half of the white dross is currently landfilled along with almost all of the black dross, and the annual cost to the UK industry of landfilling this waste is about £90 million per year. There is no commercially viable method of recovering the aluminium, which is potentially recyclable from these drosses, and no current conventional process has the custom-built capability to avoid their disposal to landfill. The practice of landfilling aluminium dross has raised problems for both industry and environment, because of potential leaching of heavy metals into groundwater from the landfill. The black dross has been physically and chemically characterised. The results show that the dross contains mostly metallic aluminium, aluminium nitride, alumina, sodium chloride, potassium chloride and silica with almost 50% of the dross being a mixture of sodium chloride and potassium chloride. A counter current leaching process has been developed to recycle the salts back to the secondary furnace. The environmental impact of black dross has been investigated using simulated landfill conditions. Leachability studies were carried out using water, and other leach media to model the following conditions: humic acid-containing systems, acid rain (pH 2.5), and acetic acid solutions (pH 5). Up to 60% of the dross was leached out in all media with the production of the saline solution providing the major impact. Only small amounts of aluminium were leached out under all these condition. No leachability behaviour was detected once the black dross was washed. So landfilling washed black dross can minimise both environmental and economical problems. Black dross residue, after washing with water, is enriched with alumina. Added value chemicals (of >95% purity) including aluminium hydroxide, alumina, aluminium chloride, aluminium nitrate, aluminium sulphate and aluminium carboxylates have been prepared using the washed black dross. Preliminary calculations have shown that the technology developed to recycle black dross to added-value chemicals is economically viable. A methodology has been developed which enables low grade alumnium waste, black dross, to be treated, commercially viable chemicals to be prepared, reagent use to be minimised through recycle and the diversion of millions of tonnes of furnace residue from landfill.
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KRENTZ, ALLISON NICHOLE. "INVESTIGATION ON THE CHEMICAL ASSOCIATION OF IMPORTANT ELEMENTS IN SEAWEED USING SEC-ICP-MS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1163041395.
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Collot, Anne-Gaelle. "Co-processing of coal and biomass in a fixed-bed reactor : products distribution and trace elements partitioning." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327030.
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Onyegbule, Nkele. "Composite low temperate hydrogen storage material on the basis of iron-titanium alloy." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6344_1242888003.
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It is widely believed that hydrogen will, within a few years, become the means of storing and transporting energy. The reason is the depletion of hydrocarbons and the relatively facile production of hydrogen from various renewable sources of energy. Hydrogen can be combusted in an efficient way in a fuel cell with water as emission product. The overall goal of the project was to deevlop the knowledge base for solid-state hydrogen storage technology suitable for stationary and mobile applications. The aim of this research was to develop a novel composite hydrogen storage material with high wt% storage capacity, high intrinsic safety, appropriate thermodynamics, high mechanical strength, reversibility of the system and fast kinetics based on a well known "
low temperature"
intermetallic alloy (Ti/Fe) as the core.
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Sandelin, Kristoffer. "Chemical equilibrium studies on trace elements and on two process problems in solid fuel combustion /." Åbo : Åbo akademi university, 2002. http://catalogue.bnf.fr/ark:/12148/cb40124384q.
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Higgitt, Catherine L. "NMR studies of arene transition metal complexes : structure, dynamics and reactivity." Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298537.
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Ramjuttun, Ravindlall. "The chemical speciation of chromium in seawater by Cathodic stripping voltammetry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0018/NQ47509.pdf.
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Hayes, Warwick Jay. "Chemical relationships in waters and sediments of some urban streams, with particular reference to heavy metals and phosphorus." University of Technology, Sydney. Department of Environmental Biology and Horticulture, 1996. http://hdl.handle.net/2100/361.
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This thesis describes two studies of the chemistry of freshwater streams in the Sydney basin. The first was a survey of 86 waterways, sampled under low conditions. Samples were generally low in salinity, soft, of poor buffering capacity and dominated by sodium and chloride. C0-dominance by calcium, magnesium and (bi)carbonate occured in a number of particular cases. Multivariate analyses indicated three groups, separated primarily by levels of dissolved nutrients, trace metals, turbidity and colour. Groupings were associated strongly with the type of catchment. Streams in areas relatively unaffected by human influence had notable uniformity in chemistry, while those from developed catchments were varied. Heavy metal contamination was relatavely low, although a few of the samples displayed inordinately large levels of one or more metals. In such cases the more extreme measurements of phosphorus and nitrogen were also seen. The findings were consistant with occasional or localised elevation of contaminant levels. The second study invloved monitoring of three Hawkesbury Sandstone streams. Sampling of surface waters, interstial waters and sediments was performing at irregular intervals over a two year period at three stations within each site. The streams predominantly existed under low conditions and showed similar major ion chemistries to the majority of the survey samples. Levels of calcium and total carbonate, plus heavy metals and nutrients were generally higher in the urbanised creeks, comapred to the reference strema. During a heavy storm, high levels of nutrients, suspended solids and colour were detected in all surface waters at peak-flow, as well as alkaline pH, oxidising redox, and reduced conductivity, alkalinity and hardness. The sandy sediments were characterised by very low levels of organic matter and cation exchange capacity. Sequential extractions identified that the sums of secondary phase lead, zinc and copper were over nine, four and two times that of the corresponding residual, respectively. Greatest proportions of zinc and lead were associated with coatings of iron and maganese oxides, or coarse waste particles. Copper was preferentially associated with organic matter. Concentration gradients between interstitial and surface waters were rare and release of sedimentary constituents should occur from the upper-most particulates. Poor water and sediment qualities were often observed in the urban sites. Poor water quality was also seen on occassion in the reference stream. However, since poor sediment quality was not detected at those times and interstitial waters for all sites displayed high within-site variability, surface waters were considered the most reliable short-term indicator of condition for Hawkesbury Sandstone streams. Multidimensional scaling showed that all streams had distinct water and sediment chemistries. High levels of temporal and spatial variability were apparant within the urbanised sites - particularly in interstitial waters - mostly due to concentrations of heavy metals, phosphorus and suspended solids. Seasonal differences were detected, but only in terms of the level of variability between summer and winter samples.
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Stange, Simone Moraes. "O estudo dos elementos químicos numa abordagem ciência, tecnologia e sociedade." Universidade Tecnológica Federal do Paraná, 2012. http://repositorio.utfpr.edu.br/jspui/handle/1/1258.
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Acompanha: Guia didático para o ensino de química: O estudo dos elementos químicos e sua identificação na abordagem Ciência, Tecnologia e Sociedade (CTS): perspectivas de uma aprendizagem crítica para a 2.ª série do ensino médioEsta dissertação teve como objetivo geral desenvolver o estudo dos elementos químicos numa abordagem Ciência, Tecnologia e Sociedade, visando contribuir para a formação conceitual, procedimental e atitudinal mais crítica dos educandos da 2.ª série do ensino médio da Escola de Educação Básica Barão de Antonina, na cidade de Mafra, no estado de Santa Catarina. Os objetivos específicos da pesquisa foram identificar a concepção dos educandos sobre as relações sócias da ciência e da tecnologia, levantar os conhecimentos prévios dos alunos sobre os elementos químicos, desenvolver atividades que promovam o estudo dos elementos químicos numa abordagem Ciência, Tecnologia e Sociedade (CTS), utilizando artigos apresentados e selecionados em Revista de Divulgação Científica (RDC) e apresentar um produto educacional, em nível de Guia Didático, que possa ser disseminado, analisado e utilizado por demais professores da educação básica –ensino médio, na disciplina de Química, como exemplo de prática pedagógica numa abordagem CTS. A abordagem metodológica que norteou este estudo foi a pesquisa qualitativa de natureza interpretativa com observação participante. A técnica de coleta de dados foi centralizada na observação participante, anotações em diário de campo, produções escritas dos alunos, fotografias e filmagens, segmentos esses que foram transcritos. Os dados da pesquisa foram coletados e analisados, inicialmente por meio da verificação das concepções prévias dos vinte e um educandos (21), envoltos no processo, tendo-se em conta a relação à temática apresentada. Esse fator possibilitou o direcionamento das atividades para categorias de análise, as quais foram delimitadas por uma etapa exploratória e uma pesquisa-ação, em que os educandos tiveram a oportunidade de participar de forma ativa, cooperativa, intervindo na construção do estudo, com seus saberes, sugestões e reflexões sobre as relações sociais do conhecimento científico e tecnológico. Assim, foi possível desenvolver o processo de construção coletiva da proposta para o enfoque do tema sugerido, pois como produto final se elaborou um guia didático, no qual constam as atividades desenvolvidas. As principais percepções da pesquisa trazem contribuições para ratificar a essencialidade de implementar ações no ato de ensinar e aprender, de modo a aprimorar práticas docentes no ensino de Química, bem como a continuidade da postura reflexiva acerca da Ciência e da Tecnologia, pelos educadores e educandos, viabilizando uma jornada pedagógica produtiva vinculada à formação do cidadão do século XXI.
This work aimed to develop the study of the chemical elements in an approach Science, Technology and Society, to contribute to the formation conceptual, procedural and attitudinal more critical of the two students. Grade school, School of Basic Education Barão de Antonina in the town of Mafra, the state of Santa Catarina. The specific objectives of the research were to identify the students 'design partners on relations of science and technology, raise the students' prior knowledge about chemicals, develop activities that promote the study of the chemical elements in an approach Science, Technology and Society (CTS ) using articles submitted and selected in Journal of Science Communication (RDC) and introduce an educational product, in terms of Didactic Guide, which can be disseminated, analyzed and used by other teachers of basic education - high school, the discipline of chemistry, as an example of a pedagogical approach CTS. The methodological approach that guided this study was the interpretative nature of qualitative research with participant observation. The technique of data collection was focused on participant observation, field diary notes on, students' written productions, photographs and film footage, these segments were transcribed. The survey data were collected and analyzed, initially by means of verification of previous conceptions of twenty-one students (21), wrapped in the process, taking into account the relationship to the theme presented. This factor allowed the targeting of activities to categories of analysis, which were bounded by an exploratory stage and an action research, in which students had the opportunity to participate in an active, cooperative, intervening in the construction of the study, with their knowledge , suggestions and reflections on the social relations of scientific and technological knowledge. Thus it was possible to develop the process of collective construction of the proposed approach to the theme suggested, because as the final product has a guide to teaching, in which the activities listed. The main perceptions of research contributions bring to ratify the essential actions to implement the act of teaching and learning, in order to improve teaching practices in the teaching of chemistry as well as the continuity of reflexive stance on Science and Technology, for educators and students , enabling a productive educational journey linked to the formation of the citizen of the XXI century.
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Ruiz-Morales, Yosadara. "The calculation and interpretation of NMR chemical shifts in compounds of transition metals and heavy elements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ31071.pdf.
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Seclaman, Alexandra Catalina. "Chemical and physical behaviour of the trace elements in the silicate melts of the Earth's mantle." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN004/document.
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Nous avons étudié des magmas ferrifères silicatés magnésiens à la pression du manteau terrestre en utilisant la dynamique moléculaire (First Principles Molecular Dynamics). Les résultats de l’équation d’état que nous avons obtenus à partir de nos simulations ont été utilisés pour créer un modèle chimique et minéralogique pour les zones de très basse vitesse sismique (ULVZ, anomalies régionales dans le manteau proche de la limite noyau-manteau). De plus, nous avons étudié le comportement du Ni, du Co et du Fe dans ces magmas et établi la dépendance du spin en fonction de la concentration, de la pression, de la température et du degré de polymérisation du magma silicaté. Nous avons montré qu’une baisse du spin moyen peut être corrélée au changement de pente (kink) observé précédemment pour les coefficients de partage du Ni et du Co. Nous avons analysé la structure du magma pour toutes les compositions étudiées en fonction de la pression. Nos résultats donnent un nouvel aperçu de la coordination des éléments majeurs et traces dans les magmas silicatés de différents degrés de polymérisation. Nous interprétons l’anomalie de coordination Ni-O en fonction de la pression comme un changement d’état de spin. L’effet de la polymérisation du magma silicaté sur les coefficients de partage du Co, du Ni et du W entre le métal et le magma silicaté a été étudié par expériences multi-enclumes en conditions isobares et isothermes. Nous avons réalisé des simulations FPMD de magmas à des degrés de polymérisation similaires aux expériences afin d’expliquer le caractère de plus en plus lithophile du W lorsque le degré de polymérisation du magma silicaté diminue. Nous proposons une explication structurale pour expliquer l’affinité décroissante apparente du W dans les magmas silicatés dépolymérisésWe explore Fe-bearing Mg-silicate melts through the pressure regime of the Earth’s mantle using First Principles Molecular Dynamics (FPMD). The equation of state results we obtained from our simulations are used to create a chemical and mineralogical model for Ultra-Low Velocity Zones (anomalous region on the mantle side of the core-mantle boundary). Furthermore we study the behaviour of Ni, Co, and Fe in these melts, and asses their spin-crossover dependencies on their concentration, pressure, temperature, and the degree of polymerization of the silicate melts. We show that a decrease in the average spin can be correlated with the previously observed kink in the partitioning coefficient of Ni and Co. We investigate the melt structure of all the compositions studied as a function of pressure. Our results provide new insight into the coordination of major and trace elements in silicate melts with different degrees of polymerization. We interpret the anomalous Ni-O coordination trend with pressure as the result of the spin state change. The effect of silicate melt polymerization on the partitioning of Co, Ni, and W between a metal and silicate melt, is investigated at isobaric and isothermic conditions using multi-anvil experiments. We have performed FPMD simulations of melts with similar degrees of polymerization as the experiments in order to explain the increasing lithophile character of W with the decrease in polymerization of the silicate melt. We propose a structural explanation for tungsten’s apparent increased affinity for depolymerized silicate melts
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Wendt, Eliéser Viégas. "Análise de elementos químicos em microalgas dulcícolas avaliadas como matéria-prima para produção de biodiesel e seus coprodutos." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4166.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The purpose of this study was to determine the composition of chemical elements in freshwater microalgae evaluated as feedstock for biodiesel production in order to assess possible consequences on the biodiesel quality and to determine whether the use of residual biomass as animal feed. So the 26 chemicals elements in 76 freshwater algae samples, 39 microalgae biomass obtained once direct transesterification, 6 oilseeds, one sample of beef tallow as well as biomass, oil and biodiesel of microalgae Desmodesmus ssp. were measured by ICP-OES. Microalgae stood out compared to conventional feedstock due to higher contents of Na and Fe, moreover chemical elements such as Al, B, Cu, Mn, Sn, Zn and as Fe, are not monitored and may be existing in microalgae biodiesel. Thru direct transesterification procedure, most of the macronutrients constituents of microalgae is lost. Residual biomass by solvent extraction process keeps the mineral composition and in this case, is the most suitable for animal feed. The contents of chemical elements from Desmodesmus ssp. biomass decrease throughout the biodiesel production process by direct transesterification. However, the P content in biofuel was 127 mg/kg, about 13 times beyond the specification, so it being necessary the pretreatment consequence to proceed the transesterification. The study demonstrated that standardization of biodiesel quality control should include the control of other chemicals, further those already monitored, if biodiesel is mainly derived from microalgae feedstock.
O objetivo deste trabalho foi avaliar a composição de elementos químicos em microalgas dulcícolas avaliadas como matéria-prima para produção de biodiesel visando estimar possíveis consequências na qualidade do biodiesel e determinar a possibilidade de aproveitamento da biomassa residual como ração animal. Para isso foram determinados por ICP-OES os teores de 26 elementos químicos em 76 amostras de microalgas dulcícolas, 39 biomassas das microalgas obtidas após procedimento de transesterificação direta, 6 sementes de oleaginosas, 1 amostra de sebo bovino e, finalmente, biomassa, óleo e biodiesel obtido a partir da microalga Desmodesmus ssp. As microalgas destacaram-se em relação às matérias-primas convencionais pelos elevados teores de Na e Fe. Também foram encontrados elementos químicos como Al, B, Cu, Mn, Sn, Zn e que, assim como o Fe, não são monitorados e poderão estar presentes no biodiesel de microalgas. Durante o procedimento de transesterificação direta, boa parte dos macronutrientes constituintes da microalga é perdida. Já a biomassa residual do processo de extração por solvente mantém a composição mineral e, neste caso, é a mais indicada para a utilização na alimentação animal. Os teores dos elementos químicos da biomassa da microalga Desmodesmus ssp. diminuem ao longo do processo de obtenção de biodiesel via transesterificação direta. Entretanto, a concentração de P no biocombustível foi de 127 mg/kg, cerca de 13 vezes acima do especificação, sendo necessário neste caso, efetuar o tratamento do óleo via degomagem antes de proceder a transesterificação. O trabalho demonstrou que a normalização do controle de qualidade de biodiesel deve contemplar o controle de outros elementos químicos, além dos já monitorados no biodiesel, principalmente se o biodiesel for obtido a partir de microalgas como matéria-prima graxa.
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Reis, Rogério Alves de Sousa. ""Caracterização de componentes inorgânicos em suplementos nutricionais pelo método de análise por ativação com Nêutrons"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-01062007-161704/.
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O controle da composição dos elementos presentes nos suplementos nutricionais é de grande importância devido ao crescente consumo e a comercialização de diversos tipos e marcas destes produtos. A determinação da quantidade de elementos nos suplementos torna se necessária para comparar com os valores declarados nos seus rótulos. Neste trabalho, a ativação com nêutrons foi aplicada à análise de 11 amostras de suplementos, adquiridos em farmácias e em lojas de produtos naturais. As amostras, adquiridas nas formas de cápsulas ou comprimidos foram moídas para se obter as na forma de pó homogêneo. As amostras e os padrões sintéticos dos elementos foram irradiados no reator nuclear de pesquisas IEA-R1. Irradiações de 8 h sob um fluxo de nêutrons térmicos de 5x1012 n cm 2 s-1 foram realizadas para a determinação dos elementos Ca, Co, Cr, Fe, Se e Zn e para a determinação dos elementos As, Cu, Fe, K, Na as amostras foram irradiadas por 1 h sob fluxo de nêutrons térmicos da ordem de 1x1012 n cm 2 s-1. As medidas das atividades gama induzidas foram realizadas usando um detector de Ge hiperpuro acoplado a um espectrometro de raios gama. Os resultados das quantidades obtidas nas amostras de suplementos foram em geral, concordantes com os valores apresentados nos seus respectivos rótulos. Elementos tóxicos como As, Cd, Hg e Sb não foram detectados em nenhuma das amostras. Para o controle da qualidade dos resultados analíticos com relação à exatidão e precisão foram analisados os materiais certificados de referência NIST 1400 Bone Ash e NIST 1633b Coal Fly Ash ambos da National Institute of Standards and Technology (NIST). Os resultados obtidos nestes materiais de referência apresentaram uma boa precisão e exatidão e os valores de Z score ou diferença padronizada obtidos das análises, foram menores que 2 indicando que os resultados obtidos são satisfatórios e estão dentro da faixa dos valores dos certificados a um nível de confiança de 95%.The control of element composition in nutritional supplements is of great interest due to increasingly high consumption and a large diversity and brands of these products offered in market. Therefore, there is the necessity to evaluate the element contents in the supplements and to compare with those values declared on the labels. In this study neutron activation analysis (NAA) was applied to evaluate the element composition of 11 commercial nutritional supplement brands bought in natural product drugstores and pharmacies. These samples acquired in capsule or tablet forms were ground to a homogeneous powder. The samples were irradiated together with the elemental standards in the IEA-R1 nuclear research reactor. Irradiations of 8 h under a thermal neutron flux of 5x1012n cm-2s-1 were carried out for Ca, Co, Cr, Fe, Se and Zn determinations. For Cu, K and Na determinations thermal neutron flux of 1x1012n cm-2s-1 was used and, the exposure time was 1h. The induced gamma activities were measured using a hyperpure Ge detector coupled to a gamma ray spectrometer. The obtained results compared with the values of the labels of nutritional supplements presented good agreement for most of the elements. Toxic elements such as As, Cd, Hg and Sb were not detected in the samples. For quality control of the analytical data, certified reference materials NIST 1400 Bone Ash and NIST 1633b Coal Fly Ash provided by the National Institute of Standards and Technology were also analysed. Accuracy and precision of these results were evaluated. The obtained Z score values were lower than 2 indicating that the data are within the ranges of certified values at 95% confidence level.
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Saqib, Naeem. "Distribution and chemical association of trace elements in incinerator residues and mining waste from a leaching perspective." Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-48933.
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Incineration is a mainstream strategy for solid waste management in Sweden and all over the world. Improved knowledge and understanding about the distribution of trace elements (in ashes) during incineration, and how trace element partitioning respond to the changes in waste composition, are important in terms of combustion process optimization and plant efficiency. Moreover, determination of chemical association of trace elements in ashes are vital for avoiding environmental concerns and to promote possible reuse. In this study, partitioning of trace elements in ashes during incineration as function of input waste fuel and incineration technology was investigated. Further, chemical association of trace elements in resulting ashes was studied. An evaluation was also performed about feasibility of metal extraction from sulfidic mining waste and flotation tailings. Moreover, green liquor dreg (GLD) was tested with respect to stabilization of metals within the sulfidic mining waste. Findings showed that the total input of trace elements and chlorine affects the partitioning and increasing chlorine in the input waste caused increase in transfer of trace elements to fly ash especially for lead and zinc. Vaporization, condensation on fly ash particles and adsorption mechanisms play an important role for metal distribution. Firing mixed waste, especially biofuel mix, in grate or fluidized (CFB) boilers caused increased transfer into fly ash for almost all trace elements particularly lead and zinc. Possible reasons might be either an increased input concentration of respective element in the waste fuel, or a change in volatilization behavior due to the addition of certain waste fractions. Chemical association study for fly ashes indicated that overall, Cd, Pb, Zn, Cu and Sb are presenting major risk in most of the fly ashes, while in bottom ashes, most of elements are associated with stable fraction. Further, fuel type affects the association of elements in ashes. Chemical leaching of mining waste materials showed that sulfuric acid (under different conditions) is the best reagent to recover zinc and copper from sulfidic mining waste and also copper from flotation tailings. GLD indicates potential for metal stabilization in mining waste by reducing the metal mobility. Extraction methods could be applied to treat mining waste in order to meet the regulatory level at a specific mining site.Similarly stabilization/solidification methods might be applied after leaching for recovery of metals.
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Uba, Ikenna. "Concentrations of selected chemical elements in organs and tissues of polar bears (Ursus maritimus) from East Greenland." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23301.
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Polar bears from Greenland are exposed to various chemical contaminants e.g. POPs and chemical elements, which are ingested by feeding on contaminated marine mammals, e.g. ringed seals. This study analyses the concentration of selenium, cadmium, mercury, lead, zinc and arsenic in muscles, kidney, liver and other tissues in both polar bears and ringed seals from East Greenland sampled in 2011 and 2012. Also, significant correlations between elements are in all tissues is reported, as well as the degree of exposure of the native Inuit people to these elements through the consumption of liver and meat from both the bears and seals.
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Peiravi, Meisam. "CONTAMINANTS REMOVAL AND RARE EARTH ELEMENTS RECOVERY FROM COAL MINE DRAINAGE BY USING (BIO)(ELECTRO) CHEMICAL METHODS." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1581.
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Mining activities, as essential as they are for our economy and our society, bring pollutants such as acid mine drainage (AMD) which contains dissolved metal(loid)s into the environment. There are different technologies currently being practiced to treat AMD, but many of these methods are prohibitive in industry due to high energy, material and labor requirements. This study investigated two emerging technologies to treat AMD with high removal rates of some metals. In addition, as AMD contains strategic metals such as rare earth elements (REEs), hydrometallurgical and biosorptive approaches were used to recover REEs from AMD, hydrometallurgical recovery method was also applied for coal by-products for the method developed. A two-chamber bioelectrochemical system (BES) was used to remove different types of metals from AMD. After 7 days, the pH of the cathode solution increased from 2.5 to 7.3. More than 99% of Al, Fe and Pb were removed, and removal rates of 93%, 91%, 89% and 69% were achieved for Cd, Zn, Mn, and Co, respectively, at the biocathode. Energy-dispersive X-ray spectroscopy (EDS) studies revealed the deposition of the various metals on the cathode surface, and some metals were detected in precipitates from the cathode chamber. During the BES operation, ~30-50 mV of closed circuit voltage was obtained for different conditions. A single-chambered BES study was conducted for the removal of Cd, Ni, and Mn in mine drainage. Compared to a double chamber, a single chamber BES is easier to design and operate. The removal process was studied with activated sludge from a local wastewater treatment plant. The effect of applied voltage, time, and initial concertation of these metals on their removal rate was studied. For Cd initial concentrations of 625 and 165 µg/L, 1.0 V showed the highest removal efficiency, and ~93 and 95% of Cd were removed, respectively. For a Ni initial concentration of 2,440 µg/L, 72% was removed under 1.0 V compared to the control of 77%. However, for a lower initial Ni concentration of 190 µg/L, 1.0 V was better compared than other conditions, and it removed 92% of Ni. For a Mn initial concentration of 1,800 µg/L, 1.0 V had a better result, however, only ~19% of the Mn was removed. For a lower Mn initial concentration of 390 µg/L, 1.0 V was favorable only at 24 h and the removal rate was ~37%. Nanoscale zerovalent iron (nZVI) was used to remove contaminants from AMD. These contaminants include transition metals (Co, Ni, Cu, Mn, and Zn), alkali and alkaline earth metals (Li, Mg, and Ca), metalloid (As), nonmetals (Se and S), and active metal (Al). Purchased nZVI in concentrations of 10-6500 mg/L was used for a reaction duration of up to 480 min. The pH of the AMD increased linearly with increasing concentrations of nZVI, with a maximum of 6.0±0.1 at 6500 mg/L of nZVI. Cu and Al had the highest removal rate among all other elements. With 10 mg/L of nZVI, ~100% of Cu was removed within 120 min. Up to ~98% of Al was removed with 5000 mg/L of nZVI in 480 min. Reuse of the purchased nZVI was studied for the first time for AMD treatment; however, after reuse in the second cycle, the nZVI was no longer effective. Lab-made nZVI by the precipitation method was tested for a longer time of 48 h. Removal rates for different elements did not change after ~8 h (e.g., 480 min), and in general, the lab-made nZVI had better removal efficiency compared to the purchased nZVI, with removal rate of ~28-79% when using 80 mg/L of the lab-made nZVI. Besides Cu, Al, Ni, and Co, successful removal of Mg and Ca, as well as S, Co, Li, As, and Se from AMD was reported for the first time by using nZVI. Different coal ranks were examined for REE concentration from coal ash. Maximum REE content of more than 700 mg/kg was observed for the highest-rank coal (anthracite) sample, and that was used for leaching and recovery studies. Hydrometallurgical processes including leaching, solvent extraction, stripping, and precipitation were performed to recover REEs from coal ash. Nitric acid leaching tests were conducted at 95 ℃ using a 4×2×2 factorial design. The results indicated that the highest rate of light REEs (LREEs) recovery was achieved at the highest molarity of the acid solution, lowest solids content and longest retention time. However, the highest rate of heavy REEs (HREEs) recovery needed only an intermediate level of acid molarity. The highest recovery rates of 90% for LREEs and 94% for HREEs were obtained. Recirculation of the leachate was conducted to prepare the REE-concentrated solution for the solvent extraction. After two stages of leaching, a 33 mg/L of TREE concentration was obtained in the leachate. Solvent extraction (SX) tests conducted using three different extractants, namely, TBP, D2EHPA and Cyanex 572, and their combinations showed that D2EHPA was the best extractant for recovering REEs from the nitric acid leachate solution with an extraction efficiency of 99%. Nitric acid and sulfuric acid and their mixture were used in the stripping tests. The effect of solvent concentration (in the SX process) was also studied in the stripping stage. When 50% solvent concentration was used, a maximum of 58% stripping recovery was obtained. Oxalic acid helped precipitate ~94% of total REEs (TREEs) from the above aqueous solution. Calcination of the product was performed to reach a final product of 0.8% rear earth oxides (REOs). The same process flowsheet was also successfully tested for another coal ash sample. To recover REEs from AMD, two different approaches were carried out including hydrometallurgical technique and more environmentally friendly approach- biosorptive recovery. A complete process flowsheet including either solvent extraction or biosorption, followed by stripping, and precipitation was developed to recover REEs from an unconventional source of AMD for the first time. At the natural pH of 2.5 almost all REEs were extracted from the solution. Metal-loaded organic solution was reused for three cycles, and it was shown that after three cycles, there was no major reduction in the capacity of the extractant. Striping with 6.0 M HNO3 recovered 23.9±0.7, 74.7±2.1, and 53.1±1.4% of LREEs, HREEs, and TREEs from the organic phase accordingly. Using oxalic acid, and for pH of 2.0, 92.9±2.8% of LREEs, 10±1.5% of HREEs, and 56.2±1.8% of TREEs were precipitated. In the biosorptive extraction, >99% of TREEs were extracted from the solution. The REE-bearing bacteria was also stripped with 6.0 M HNO3, 2871.3±114.8 µg/L (45.0±1.8%) LREEs, 3851.0±154.0 µg/L (65.0±2.6%) HREEs, and 6722.0±268.9 µg/L (50.0±2.0%) TREEs were obtained. Both hydrometallurgical and biosorptive methods extracted almost all of the REEs in the AMD, though pH was adjusted to 4.0 for the biosorptive method. After stripping, comparable amounts of TREEs were obtained by both methods.
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Liu, Hongjun. "Synthesis and study of functional oxides based on earth-abundant elements." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI049/document.
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Au cours des dernières années, l'électronique à base d’oxydes métalliques a attiré de plus en plus d'attention au sein de la recherche, principalement grâce à leur potentiel en termes de réduction de coûts ainsi que la possibilité de développer une électronique transparente. Il existe plusieurs applications potentielles concernant les oxydes métalliques : le photovoltaïque, les transistors à couche mince et la photo-électrochimie. Il existe plusieurs oxydes métalliques de type n avec d'excellentes propriétés électroniques, telles que l'oxyde de zinc dopé à Al. Mais la mise au point de dispositifs entièrement à base d’oxydes métalliques est largement entravée par les mauvaises propriétés électroniques des oxydes de type p jusqu'à présent étudiés. Par conséquent, il est nécessaire de développer des matériaux semi-conducteurs d'oxyde métallique de type p présentant de meilleures propriétés électriques.Dans cette thèse, l'optimisation du dépôt de films minces de Cu2O a été effectuée par MOCVD assisté par aérosol (AA-MOCVD). Par conséquent, des films de Cu2O homogènes et de très forte cristallinité ont été déposés à basse température (environ 335 °C) sans contamination détectable de carbone. De plus, grâce à l'incorporation de l'humidité durant les dépôts, la taille des grains et l'orientation des films Cu2O peuvent être modulées, ainsi des films de Cu2O avec une texturation (111) et une taille de grains > 300 nm ont été obtenus. Pour les films Cu2O optimisés, la mobilité peut atteindre un maximum de 15 cm2 / V.s avec une concentration de porteur de l'ordre de 1015 cm-3. Enfin, un excellent comportement diode a été observé en combinant les films de Cu2O optimisés avec du ZnO, obtenant un rapport on/off supérieur à 104.En raison de l'incompatibilité entre la fenêtre de stabilité thermique associée à AgCuO2 et les températures nécessaires pour déposer des composés Ag et Cu par CVD avec les précurseurs utilisés, le dépôt direct d'AgCuO2 n'a pas pu être obtenu. Ainsi, des techniques de revêtement couche mince à base de solution ont été adoptées pour le dépôt de film AgCuO2. En particulier, la méthode SILAR a permis le dépôt de films minces d’AgCuO2. Grâce à une couche d’amorce sur substrat de verre appropriée, des couches d'AgCuO2 denses et continues ont été revêtues, avec une valeur RMS minimale de 8 nm. Les films d’AgCuO2 déposés avaient une phase presque pure. Les propriétés optiques et de transport des films minces AgCuO2 ont donc été analysées pour la première fois. Les mesures de transmittance ont confirmé la faible largeur de bande interdite prédite d’AgCuO2 (1,2 eV), tandis que grâce à l’utilisation de la formule de Tauc, nous avons constaté que ce matériau est plus susceptible d'avoir une bande interdite directe, en accord avec les calculs DFT publiés. Grâce aux mesures de l'effet Hall, les films AgCuO2 déposés ont été confirmés comme étant de type p. La plus faible résistivité atteinte est de 0,2 Ω.cm. En outre, ces films avaient une densité de porteurs de charge de l'ordre de 1017 cm-3 et la meilleure mobilité atteinte était de 24 cm2 / V.s. En comparaison avec les composés de type p de delafossite précédemment rapportés (M, Al, Cr, Ga, etc.), ce matériau présente la plus petite largeur de bande interdite (intéressant notamment pour l'application photovoltaïque) et une conductivité assez élevée. La caractéristique la plus intéressante est que le problème général de la faible mobilité des transporteurs dans ces composés delafossite a été résolu dans cet AgCuO2, grâce à sa structure électronique mixte et à la délocalisation des charges. Ainsi, ces résultats de caractérisation sans précédent ouvrent la voie à l'utilisation de films AgCuO2 dans des dispositifs fonctionnelsIn recent years, metal oxide electronics has attracted more and more attention in research, mainly thanks to their potential lower cost and the possibility they offer to develop transparent electronics. There are several potential applications concerned with metal oxides including photovoltaics, thin film transistors and photo-electrochemistry. There are several n-type metal oxides with excellent electronic properties being well developed, such as Al doped zinc oxide. But the fabrication of devices fully made with metal oxides is largely impeded by the poor electronic properties of the p-type oxides so far studied. Therefore, there is the need for developing p-type metal oxide semiconducting materials with better electrical properties.In this thesis, the optimization of pure Cu2O thin film deposition was conducted using Aerosol Assisted MOCVD (AA-MOCVD). As a result, homogenous Cu2O films were deposited at low temperature (about 335 °C) without detectable amount of carbon contamination with high crystallinity. In addition, by incorporation of humidity during the deposition, particle size and the orientation of the Cu2O films could be tuned, thus Cu2O films with (111) textured large grain sizes (> 300 nm) were achieved. For optimized Cu2O films, the mobility can reach a maximum of 15 cm2/V.s with carrier concentration in the order of 1015 cm-3. Lastly, an excellent diode behaviour was observed by combining the optimized Cu2O films with ZnO, obtaining an on-off ratio exceeding 104.Besides the Cu2O optimization, the deposition of AgCuO2 by MOCVD was also tackled. In order to do so, the deposition of silver and silver oxide thin films was previously optimized. For that, two new silver precursors, namely, Ag(hfac)phenanthroline and Ag(hfac)triglyme were synthesized and fully characterized. High quality Ag coatings could be obtained with both precursors. Silver oxide films were obtained through electrochemical oxidation and oxygen plasma treatment of pre-deposited Ag coatings.Due to the incompatibility between the thermal AgCuO2 stability window and the temperatures needed to deposit Ag and Cu compounds by CVD with the precursors used, the direct deposition of AgCuO2 could not be obtained. Thus, solution based thin film coating techniques were adopted for AgCuO2 film deposition. In particular, Successive Ionic Layer Adsorption and Reaction (SILAR) allowed the deposition of AgCuO2 thin films. Using a proper seed layer on glass, dense and continuous AgCuO2 films were coated, with minimum RMS value of 8 nm. The deposited AgCuO2 films had almost pure phase. The optical and transport properties of AgCuO2 thin films were thus carried out for the first time. Transmittance measurements confirmed the predicted low bandgap of AgCuO2 (1.2 eV), while by using the Tauc formula, we found that this material is more likely to have a direct bandgap, in agreement with published DFT calculations. Thanks to Hall Effect measurements, the deposited AgCuO2 films were confirmed to be p-type. The lowest resistivity achieved was 0.2 Ω.cm. In addition, those films had carrier density in the order of 1017 cm-3 and the best mobility achieved was 24 cm2/V.s. Comparing with the previously reported CuMO2 (M= Al, Cr, Ga etc) delafossite p-type compounds, this material has shown the lowest bandgap (appropriate for photovoltaic application) and rather high conductivity. The most interesting characteristic is that the general problem of low carrier mobility in those delafossite compounds has been solved in this AgCuO2, thanks to its mixed-valence electronic structure and charges delocalization. Thus, those unprecedented characterization results pave the way for using AgCuO2 films in functional devices
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Jardine, Angela Beth. "Aqueous Phase Tracers of Chemical Weathering in a Semi-arid Mountain Critical Zone." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144594.
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Chemical weathering reactions are important for the physical, chemical, and biological development of the critical zone. We present findings from aqueous phase chemical analyses of surface and soil pore waters during a 15 month study in a small semi-arid mountain catchment of the Santa Catalina Mountain Critical Zone Observatory. Stream water geochemical solutes are sourced to two distinct locations - fractured bedrock baseflow stores and soil quickflow stores. Solid phase observations of albite, anorthite, and K-feldspar transformation to Ca-montmorillonite and kaolinite are supported by stream water saturation states calculated via a PHREEQC geochemical model. While differences in mineral assemblages, soil depths, and horizonation suggest greater weathering in schist versus granite lithologies and in hillslope divergent versus convergent zones, soil pore water solute ratio analysis does not readily distinguish these differences. However, preliminary investigation of aqueous rare earth elements suggests detectable lithologic and landscape positional differences warranting focus for future research efforts.
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Crilley, Leigh R. "Investigations of the physical and chemical properties of ambient fine particles in urban schools." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/65336/1/Leigh_Crilley_Thesis.pdf.
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This thesis reports a comprehensive study on the physical and chemical properties of airborne particles in Brisbane, especially around schools. The sources and potential toxicity of the particles were identified, enabling an assessment of the contributing factors to children's exposure at school. The results from this thesis give a quantitative estimate of the range of airborne particles that children are exposed to at urban schools with different traffic conditions.
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MAGALHÃES, Marcelo da Rocha Leão de. "Concentrações naturais de elementos químicos da classe insecta do fragmento florestal de Mata Atlântica Reserva Charles Darwin." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17481.
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FACEPE
Áreas naturais, assim como seus compartimentos ecológicos são, muitas vezes, negligenciados em estudos da qualidade ambiental. O compartimento insetos é extremamente importante devido sua representatividade nos ecossistemas e participação em praticamente todos os processos ecológicos mantenedores da biodiversidade. Estudos envolvendo a biomonitoração de elementos químicos são escassos no Brasil para este grupo de animais, principalmente pela inexistência de protocolos analíticos e padrões de referência para estudos ambientais. Neste trabalho, inicialmente foram avaliadas três metodologias de solubilização ácida de amostras de insetos, ou seja, o tratamento fraco (ácido nítrico a 50%), o tratamento I (ácido nítrico p.a. a 65%) e o tratamento II (ácido nítrico p.a. 65% e peróxido de hidrogênio a 35%). Após a definição do melhor procedimento de tratamento químico, as concentrações naturais de insetos foram estabelecidas para As, Cd, Cl, Cu, Fe, Mo, P, Pb, S, Sb, Th e Zn por meio das técnicas de Fluorescência de Raios-X por Energia Dispersiva (EDXRF), Espectrometria de Absorção Atômica com Forno de Grafite (GFAAS) e Espectrometria de Massas por Plasma Acoplado Indutivamente (ICP-MS). Para a garantia da qualidade do procedimento, foram utilizados os materiais de referência SRM 2976 Mussel tissue, RM 8415 Whole egg powder, SRM 1515 Apple leaves, RM 8414 Bovine muscle Powder, IAEA 336 Lichen e IAEA V-10 Hay Powder, produzidos pela Agência Internacional de Energia Atômica (IAEA) e o National Institute of Standards and Technology (NIST). Por meio deste estudo, comprovou-se a qualidade do procedimento analítico ao utilizar-se o método envolvendo HNO3 e H2O2 (tratamento II) para a solubilização das amostras de insetos e materiais de referência. Os resultados obtidos da análise quantitativa comprovaram a qualidade do procedimento analítico para a determinação de doze elementos químicos pelas técnicas analíticas empregadas. As regiões HPD foram obtidas em nível de 95% de confiança para as concentrações naturais médias de As, Cd, Cl, Cu, Fe, Mo, P, Pb, S, Sb, Th e Zn dos insetos terrestres do Refúgio Ecológico Charles Darwin, tendo resultados comparáveis àqueles de outros ecossistemas naturais. A análise estatística demonstrou a confiabilidade dos resultados obtidos para aplicação em estudos futuros referentes a insetos da Mata Atlântica de Pernambuco.
Natural areas, as well as its ecological compartments are often negligected in studies of environmental quality. The insects compartment is extremely important because of their representativeness on ecosystems and participation in almost all ecological processes for biodiversity maintaining. Studies involving biomonitoring of chemical elements are scarce in Brazil for this group of animals, especially by the absence of analytical protocols and reference standards for environmental studies. In this study, three approaches were initially evaluated of acid solubilization in insect samples, in other words, the weak treatment (50% nitric acid) treatment I (p.a. nitric acid at 65%) and treatment II (p. a. nitric acid 65 % and hydrogen peroxide 35%). After defining the best chemical treatment procedure, the natural concentrations of insects from the Refugio Ecológico Charles Darwin have been established for As, Cd, Cl, Cu, Fe, Mo, P, Pb, S, Sb, Zn and Th using Energy dispersive X-ray fluorescence (EDXRF), Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The reference materials SRM 2976 Mussel tissue, RM 84 15 Whole egg powder, SRM 1515 Apple leaves, RM 8414 Bovine muscle Powder, IAEA 336 Lichen and IAEA V-10 Hay Powder, produced by the International Atomic Energy Agency (IAEA) and the National Institute of Standards and Technology (NIST) were used to guarantee the quality of the analytical procedure. This study proved the quality of the analytical procedure when using the method involving HNO3 and H2O2 (treatment II) for solubilization of insects samples and reference materials. The results of the quantitative analysis confirmed the quality of an analytical procedure for determining the twelve chemicals used analytical techniques. The HPD regions were obtained in 95% level of confidence for the average natural concentrations of As, Cd, Cl, Cu, Fe, Mo, P, Pb, S, Sb, Th and Zn of terrestrial insects of the Refugio Ecológico Charles Darwin, having results comparable with those of other natural ecosystems. The statistical approach demonstrated the reliability of the obtained results for using in further studies on insects from the Atlantic Forest of Pernambuco, Brazil.
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SANTOS, Mariana Luiza de Oliveira. "Elementos químicos em invertebrados terrestres como indicadores de qualidade ambiental de áreas urbanas." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/19637.
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FACEPE
Invertebrados terrestres podem ser empregados como biomonitores para a avaliação da qualidade ambiental de áreas urbanas devido à capacidade de absorver substâncias químicas do ambiente por meio da alimentação ou contato direto. Ainda são poucos os estudos realizados utilizando insetos como biomonitores, mesmo sendo bastante relevantes ao considerar seu papel ecológico e densidade populacional elevada. Este trabalho foi realizado com o intuito de utilizar invertebrados terrestres como biomonitores nas áreas urbanas Manguezal Memorial Arcoverde, Reserva da Mata do Frio e Campus Tecnológico do Nordeste, todas localizadas em Pernambuco. Para fins de monitoração de impactos ambientais, foram utilizados padrões de referência para estudos ambientais da classe Insecta obtidos no Refúgio Ecológico Charles Darwin, Igarassu, Pernambuco, unidade conservação com maior grau de conservação. A coleta dos invertebrados para realização do estudo foi executada utilizando-se armadilhas com iscas de mel, laranja, sardinha e carne putrefata a fim de atrair animais com diferentes hábitos alimentares. Após a coleta, os invertebrados foram lavados e em seguida, separados em nível de ordem para realização das análises químicas. A maior diversidade de ordens de invertebrados terrestres foi encontrada na Reserva da Mata do Frio, enquanto a ordem mais abundante coletada nas áreas urbanas estudadas foi Hymenoptera. Porções-teste de 0,1 g de massa seca foram analisadas por Espectrometria de Fluorescência de Raios-X por Dispersão de Energia (EDXRF), Espectrometria de Massas com Plasma Indutivamente Acoplado (ICP-MS) e Absorção Atômica por Forno de Grafite (GFAAS). A qualidade do procedimento analítico foi avaliada utilizando-se de porções-teste dos materiais de referência SRM 2976, SRM 8414, SRM 8415 e IAEA 336. As técnicas analíticas empregadas permitiram a determinação da concentração dos elementos químicos As, Cd, Cl, Co, Cr, Cu, Fe, K, Mo, P, Pb, S, Sb, Th, U e Zn nos invertebrados das áreas urbanas estudadas. O manguezal Parque Memorial Arcoverde apresentou maiores características de ambiente impactado, devido às elevadas concentrações de Cd, Co, Cu, Mo, S, Sb e Zn nos invertebrados analisados. Na Reserva da Mata do Frio, foram obtidas concentrações superiores dos elementos químicos Cl, Cu, K e Zn, enquanto que, no Campus Tecnológico do Nordeste, o elemento químico Cd se destacou por apresentar concentração superior a faixa esperada em amostras de Hymenoptera. Considerando a relativa facilidade de coleta e análise, diversos ecossistemas puderam ser avaliados convenientemente utilizando invertebrados terrestres.
Terrestrial invertebrates can be employed as biomonitors for the environmental quality assessment in urban areas due to the ability of uptake of chemical substances through food or direct contact. Moreover, there are few studies using insects as biomonitors, even though their relevance owing to their ecological role and high population density. This work has utilized terrestrial invertebrates as biomonitors in the urban areas Parque Memorial Arcoverde, Reserva da Mata do Frio and Campus Tecnológico do Nordeste, located in the Pernambuco State, Brazil. Reference standards for environmental studies of class Insecta obtained in the Refúgio Ecológico Charles Darwin, Igarassu, Pernambuco, Brazil, a conservation unit of high conservation level, were used for environmental impact monitoring purposes. Invertebrates were sampled by using traps with honey, orange, sardine and rotten meat as attractive for animals of different food habits. After, the invertebrates were washed and then separated at the order level in order to analyze the chemical elements. The greatest diversity of orders was found in the Reserva da Mata do Frio, while the most abundant order in the studied urban areas was Hymenoptera. Test portions of 0.1 g were analyzed by Energy Dispersive X-Ray Fluorescence Spectroscopy (EDXRF), Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Graphite Furnace Atomic Absorption (GFAAS). The quality of the analytical procedure was evaluated using the reference materials SRM 2976, SRM 8414, 8415 and IAEA 336. The analytical techniques employed here allowed the determination of As, Cd, Cl, Co, Cr, Cu, Fe, K, Mo, P, Pb, S, Sb, Th, U and Zn in the invertebrates from the studied urban areas. The Parque Memorial Arcoverde mangrove was considered one of the most impacted areas according to the high concentrations of Co, Cu, Mo, S, Sb and Zn determined in the invertebrates. For the Reserva Mata do Frio, it was observed the highest concentrations of the chemical elements Cl, Cu, K and Zn, while one invertebrate sample from the Campus Tecnológico do Nordeste accumulated Cd above the expected range. Considering the relative facility of sampling and analysis, diverse ecosystems could be appropriately assessed by means of terrestrial invertebrates.
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Elias, Camila. "Amostragem sustentável de bromélias nativas para estudos ambientais em unidades de conservação." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-11122009-113925/.
Full textAbstract:
O Estado de São Paulo é caracterizado por um mosaico de paisagens formado por fisionomias vegetais como a floresta de restinga, a floresta ombrófila densa, a floresta estacional semidecidual e o cerradão, representadas, respectivamente, pelas unidades de conservação Parque Estadual Ilha do Cardoso, Parque Estadual Carlos Botelho, Estação Ecológica dos Caetetus e Estação Ecológica de Assis. Mesmo protegidas legalmente, essas áreas ocorrem, na maior parte, em regiões bastante alteradas pela ação antrópica. As epífitas, especialmente as bromélias, respondem diretamente a essas intervenções, sendo interessantes para diversos estudos ambientais. As bromélias apresentam estratégias diferenciadas para a absorção de elementos químicos a partir da serrapilheira depositada no tanque (bromélia-tanque) ou diretamente da atmosfera (bromélia atmosférica). Entretanto, o emprego dessas plantas para estudos de qualidade ambiental é comprometido por etapas da análise química, principalmente relativas à amostragem e à contaminação da superfície das folhas com material particulado. De acordo com o procedimento usual, a amostragem envolve a retirada de diversas plantas, acarretando possíveis danos aos ecossistemas. Por essa razão, a proposta desse trabalho consiste em uma metodologia inovadora de amostragem denominada sustentável, em que são retirados discos de folhas das bromélias sem a necessidade de remoção das rosetas das áreas estudadas. Considerando as diferentes formações vegetacionais, a diversidade de bromeliáceas, as características nutricionais das plantas epifíticas e a problemática de amostragem de bromélias nativas em unidades de conservação, este presente trabalho teve como objetivos específicos (I) a avaliação da composição química de bromélias nos diversos tipos vegetacionais, (II) a avaliação da composição química das diferentes espécies de bromélias, (III) a avaliação da contribuição dos modos nutricionais do tipo tanque e atmosférico e dos modos de crescimento epifítico e terrícola para a composição química de folhas de bromélias (IV) a avaliação do efeito da lavagem sobre a composição química das folhas, (V) a comparação dos resultados da amostragem sustentável com aqueles da amostragem usual e (VI) a avaliação da variabilidade da composição química dos diferentes terços das folhas e terços da planta. A análise por ativação neutrônica instrumental (INAA) foi empregada por permitir a determinação simultânea de diversos elementos químicos em elevado nível metrológico. Para cada estudo realizado, as amostras tiveram preparo específico, permitindo a análise por INAA. As bromélias apresentaram diferenças quanto à composição química entre as unidades de conservação, embora não tenha sido verificada um padrão único de distribuição dos elementos químicos, corroborando composição química inerente de cada espécie. Bromélias-tanque mostraram maiores concentrações dos elementos químicos essenciais. As folhas das plantas estudadas apresentaram concentrações levemente maiores no modo epifítico quando comparadas com aquelas crescendo sobre o solo. Os resultados obtidos demostraram a necessidade de um procedimento de lavagem para minimizar a influência de material particulado sobre as concentrações de elementos químicos nas folhas. A nova amostragem sustentável promoveu resultados comparáveis, principalmente para o terço inferior, com a amostragem usual. Ainda, aumentou-se a confiabilidade dos resultados dada a redução do número de etapas do preparo de amostras proporcionado por esta metodologia de amostragemThe State of São Paulo, Brazil, is characterized by a mosaic of landscapes formed by diverse vegetational types as restinga forest, dense ombrophilous forest, seasonal semideciduous forest and savanna woody, respectively represented by the conservation units Parque Estadual Ilha do Cardoso, Parque Estadual Carlos Botelho, Estação Ecológica dos Caetetus and Estação Ecológica de Assis. These units are legally protected, although occurring mostly in areas highly modified by anthropogenic impacts. Epiphytes, especially bromeliads, directly respond to these impacts, being interesting for environmental studies. Bromeliads have different strategies for the uptake of chemical elements from the litterfall deposited in the tank (tank bromeliad) or from the atmosphere (atmospheric bromeliad). Many steps of the chemical analysis affect the application of these plants for environmental quality studies, including sampling and leaf surface contamination with particulate matter. According to the usual procedure, sampling depends on the removal of several rosettes, which may cause impacts on the ecosystem. Therefore, the proposal of this work consists in a novel sampling methodology, named \"sustainable\", in which small disks of bromeliad leaves are collected without removing rosettes from the studied areas. Considering the different vegetation, the bromeliad diversity, the nutritional characteristics of epiphytic plants and the problem of sampling native bromeliads in conservation units, this work aimed at (I) the evaluation of chemical composition of bromeliads from diverse vegetational types, (II) the evaluation of chemical composition of different bromeliad species, (III) the evaluation of the contribution of tank and atmospheric nutritional modes, as well as epiphytic and terrestrial growth modes, for the chemical composition of bromeliads, (IV) the assessment of washing effects on leaf chemical composition, (V) the comparison of sustainable sampling results with those obtained from usual sampling and (VI) the assessment of chemical composition variability at different leaf and plant positions. Instrumental neutron activation analysis (INAA) was employed, allowing the simultaneous determination of diverse chemical elements at a high metrological level. For each study, samples were prepared accordingly before being analyzed by INAA. The bromeliads showed differences in chemical composition among the conservation units. There was no uniform distribution pattern of chemical elements among the bromeliad species, corroborating an inherent species chemical composition. Tank bromeliads showed apparently high efficiency in the uptake of essential chemical elements. The studied plants showed concentrations slightly higher in bromeliads growing in epiphytic mode when compared to those growing on soil. The results demonstrated the need for the washing procedure to minimize the particulate matter influence on the concentrations of chemical elements. The new sustainable sampling provided results comparable to the usual sampling procedure, especially for the bottom plant position. Further, the reliability of the results was increased due to the reduction of steps for sample preparation provided by this sampling methodology
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Callahan, John J. "Optoelectronic hybrid integration utilizing Au/Sn bonding." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/15461.
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H-Duke, Michelle, and University of Lethbridge Faculty of Education. "The chemistry of education : a periodic relationship." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Education, 2003, 2003. http://hdl.handle.net/10133/221.
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The purpose and focus of this research is to examine a chemistry of education and to build a metacognitive bridge between the two disciplines, chemistry and education, through autobiographical narrative development of a relational periodic table for education. The elements of teaching are integrated using the actual model of the chemical periodic table of elements as a working metaphor to re-understand teaching and education. Through the narrative analysis of the inter-and intra-relationships (the educational chemical reactions), this thesis posits a new understanding of the complex matrical relationships of education and thus expands this relational knowledge toward developing new and better methods for teachers, students and for all investors of education to engage in and experience the chemistry of education.xiii, 312 leaves ; 28 cm.
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Liu, Jian. "Chemical interferences on the atomization yield of high reduction potential elements : Signal suppression in the plasma source spectrometry." Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-05252001-113835/.
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In inductively coupled plasma spectrometry, signal suppression by acids has been recognized for a long time. It is always explained as the physical effects on the sampling processes, plasma conditions, and aerosol properties. In some cases, signal suppression apparently relates to the chemical properties of element. However, there was no publication discussed this phenomenon. In this work, it has been proven that mercury signal suppression depends on the plasma properties and nitric acid concentration. It relates to the atomization yield of mercury compounds, which is governed by the red-ox equilibrium in the central channel of plasma. Mercury complex formation equilibrium has been proven to exert in the heated droplets in plasma. The equilibrium state is governed by the complex formation with ammonium nitrate, the complex dissociation by nitric acid, and the heat obtained from plasma. Mercury halogen complex is not sensitive to the changes in acidity. Therefore, it is able to keep mercury free from nitric acid interferences and unify mercury atomization in the central channel of plasma. Similar to mercury, the uncertain signal and memory effect of platinum group elements and gold mainly arises from the chemical interference on the atomization efficiency. It not only depends on nitric acid concentration, but also on the standard reduction potential (Eo) of precious metal species in solution. Chemical interference on the spectrometric signals is governed by the robustness of the plasma, the capabilities to ingest aerosol and to protect foreign disturbance. The robustness of plasma is not equal to the excitation conditions. It has been observed that nitric acid has no significant interferences on mercury signal intensity of MIP-OES. When wet aerosol enters into the resonant cavity, it is completely desolvated in the powerful electromagnetic field. Liquid phase instantly disappears from the plasma observation zone. No doubt, the chemical equilibrium does not exist. In conclusion, chemical reactions exist in the plasma and interference the spectrometric signal. The best way to overcome the chemical matrix interferences in the plasma source spectrometry is to realize the controllable atomization.
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Vieitez, Doreen E. "The efficacy of N-stage testing versus intermediate testing in the formation of equivalence classes of chemical elements." Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/917823.
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A set of stimuli comprises an equivalence class if the three relations of reflexivity, symmetry, and transitivity are present (Sidman & Tailby, 1982). Although behaviorological researchers have suggested that the training and testing sequence may affect equivalence class formation, this has not been studied directly. The purpose of this study was to investigate the efficacy of two different arrangements of training and testing on the formation of classes of equivalent stimuli. Five middle school students were taught eight conditional discriminations with four classes of stimuli, three stimuli per class (A1B1C1, A2B2C2, A3B3C3, and A4B4C4). A fifth class of stimuli, A5B5C5, was used as control stimuli. Experimental stimuli consisted of five chemical elements, with three attributes per element (name, symbol, and atomic number). The formation of three-member equivalence classes was evaluated by testing students for symmetrical and transitive conditional discriminations involved in the training relations. Two phase arrangements were used with each student. Phase Arrangement I (incorporating n-stage testing) was as follows: (a) AM; (b) B1C1; (c) A1B1 and B1C1 mixed together; (d) test (A1C1, C1A1, A5C5, and C5A5); (e) AM; (f) B2C2; (g) A2B2 and B2C2 mixed together; (h) test (A2C2, C2A2, A5C5, and C5A5); (i) AM, B1C1, AM, and B2C2 all mixed together; and (j) test (AlCl, C1A1, A2C2, C2A2, A5C5, and C5A5). Phase Arrangement II was similar, except that test phases (d) and (h) were eliminated. Stimulus classes A3B3C3 and A4B4C4 were arranged analogously to provide a counterbalanced design. One student performed equally well on equivalence tests with both phase arrangements. Two students performed slightly better on equivalence tests with intermediate testing. One student's performance on equivalence tests demonstrated no equivalence class formation with n-stage testing and much more accurate, although varied, responding with intermediate testing. A 5th student who did not meet the pretest requirements for the study was nevertheless allowed to complete the experimental tasks because his test results were unusual. His first test score was far below chance level, but scores improved with subsequent testing. The results suggest that an intermediate testing arrangement may decrease intersubject variability and, for some individuals, may improve equivalence test performance.Department of Special Education
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BHANDARI, RISHABH. "ROLE OF CONSTITUENT ELEMENTS IN PROPANE OXIDATION OVER MIXED METAL OXIDES." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1116259229.
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Aronsson, Tim. "Chromatographic separation of rare earth elements using a novel extractant mixture." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302715.
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Sällsynta jordartsmetaller är en kritisk råvara som står inför viktiga utmaningar gällande utbud och efterfrågan. För att överkomma dessa utmaningar behövs det effektiva separationsmetoder. Den här rapporten studerar separationen av sällsynta jordartsmetaller med extraktionskromatografi. Tre olika extrakt-modifierade HPLC kolonner användes för att separera en samling av åtta sällsynta jordartsmetaller; lantan, cerium, praseodym, neodym, samarium, gadolinium, dysprosium och yttrium. Den första kolonnen innehöll ren HDEHP som extraktant, den andra ren HEHEHP som extraktant. Den tredje kolonnen innehöll en blandning av de två extrakanterna. Blandningen bestod av 15–30% HDEHP. Eluering genomfördes med salpetersyra i olika koncentrationer och applicering. Forskningsfrågan som rapporten bygger på gäller hurvida blandningen av extraktanterna kan förbättra separationen gentemot att endast använda de rena extraktanterna. Jämförelsen kolonnerna emellan baserades huvudsakligen på två parameterar, salpetersyraförbrukning och upplösning av toppar. Resultaten visar att kolonnen med endast HEHEHP hade minst salpetersyraförbrukning men gav sämst upplösning. Kolonnen med endast HDEDP hade högst salpetersyraförbrukning men gav bäst upplösning, speciellt för de fyra tyngsta ämnena; samarium, gadolinium, dysprosium och yttrium. Kolonnen med extraktantblandningen gav god upplösning för alla ämnen, speciellt för de fyra lättaste ämnena; lantan, cerium, praseodym och neodym. Eftersom denna kolonn dessutom hade relativt låg salpetersyraförbrukning är den preliminära slutsatsen att denna presterade bäst generellt. Slutsatsen är därmed att extraktantblandningen kan förbättra separationen.Rare earth elements are a crucial resource facing challenges concerning supply and demand. To meet these challenges, efficient separation methods are needed. This report investigates the separation of rare earth elements using extraction chromatography. Three different extractant modified HPLC columns was used to separate a collection of eight rare earth elements: lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, dysprosium, and yttrium. One column contained pure HDEHP as extractant, another pure HEHEHP as extractant. The third column contained mixture of the two extractants. The mixture contained 15-30% HDEHP. Elution was achieved using nitric acid as eluent in different concentrations and modes of elution. The research question guiding the work was to investigate if using a mixture of extractants could improve the separation as opposed to using only the pure extractants. The comparison was made based on two main performance parameters, nitric acid consumption and peak resolution. The results show that the column with pure HEHEHP had the lowest nitric acid consumption but yielded the worst resolution. The column with pure HDEHP had the highest nitric acid consumption but the best resolution, particularly for the four heaviest analytes, samarium, gadolinium, dysprosium, and yttrium. The column with the extractant mixture yielded good resolution for all analytes and especially for the four lightest analytes: lanthanum, cerium, praseodymium, and neodymium. Since this column also had relatively low nitric acid consumption the tentative conclusion is that it performed the best overall. The conclusion is therefor that the extractant mixture can improve the separation.
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Santos, Eliane Conceição dos. "Estudo da poluição aérea de elementos químicos pelas análises de cascas de árvore." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-24112017-142556/.
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A avaliação da qualidade do ar é um assunto de grande importância uma vez que os contaminantes da atmosfera podem causar efeitos danosos à saúde e ao meio ambiente. Nos últimos anos as cascas de árvores têm sido estudadas como biomonitores da poluição atmosférica devido à facilidade de amostragem, ampla disponibilidade e resistência das espécies arbóreas quanto às variações ambientais. No presente trabalho, um estudo da poluição aérea de elementos químicos foi realizado pela análise de cascas de Tipuana (Tipuana tipu) e Sibipiruna (Poincianella pluviosa). As cascas de árvore foram coletadas em diferentes locais da Região Metropolitana de São Paulo (RMSP) e em dois locais no interior do estado de São Paulo considerados como regiões controle. As amostras de cascas foram analisadas por meio da análise por ativação neutrônica (NAA) para a determinação de As, Br, Ca, Cl, Co, Cr, Cs, Fe, K, La, Mg, Mn, Ni, Rb, Sb, Sc, V e Zn e pela espectrometria por absorção atômica com forno de grafite (GF AAS), na determinação de Cd, Cu e Pb. No controle da qualidade analítica, os resultados das análises dos materiais de referência certificados apresentaram boa exatidão, com valores de |Z score| ≤ 2. Ensaios preliminares foram realizados para estabelecer as condições experimentais adequadas para coleta e preparo das amostras das cascas de árvore. As cascas foram coletadas em todas as possíveis faces do tronco da árvore e uma espessura de 2 mm da camada superficial da casca foi ralada e homogeneizada para as análises. Os resultados indicaram variabilidade nas concentrações dos elementos nas cascas em função da proximidade e intensidade das fontes de emissão. Além disso, os resultados indicaram quatro possíveis fontes de poluentes, sendo estes, veicular, industrial, aerossol marinho e a própria composição da casca de árvore. Os fatores de enriquecimento para os elementos determinados nas cascas de árvore indicaram maiores concentrações nas amostras coletadas na RMSP do que aqueles obtidos nas regiões controle. As concentrações de As, Cd, Co, Pb e Zn obtidas nas cascas de árvores apresentaram associação com as concentrações de material particulado (MP10) medidas pela Companhia Ambiental do Estado de São Paulo (CETESB). Os elementos Cl, Co, Mg e Ni das cascas, apresentaram correlação com as taxas de mortalidade por doenças cardiorrespiratórias em adultos. Os resultados deste estudo indicam a viabilidade do uso de cascas de árvores em estudos de poluição atmosférica de elementos químicos, especialmente nas regiões em que não há sistema de monitoramento da poluição do ar.The assessment of air quality is a matter of great importance since the pollutants of the atmosphere can cause harmful effects to health and the environment. In recent years tree barks have been studied as biomonitors of atmospheric pollution due to their easy of sampling, wide availability and resistance to environmental variations. In the present study on aerial pollution of chemical elements, the analyses of Tipuana (Tipuana tipu) and Sibipiruna (Poincianella pluviosa) tree barks were performed. The tree barks were collected at different sites in the Metropolitan Region of São Paulo (MRSP) and in two small cities of São Paulo state considered as control regions. The bark samples were analyzed by neutron activation analysis (NAA) for As, Br, Ca, Cl, Co, Cr, Cs, Fe, K, La, Mg , Mn, Ni, Rb, Sb, Sc, V, and Zn determinations and by graphite furnace atomic absorption spectrometry (GF AAS) for Cd, Cu and Pb. In the analytical quality control, the certified reference materials results presented good accuracy, with values of |Z score| ≤ 2. Preliminary tests were performed to establish adequate experimental conditions for collection and preparation of the tree barks samples. The barks were collected in all possible faces of the tree trunk and a thickness of 2 mm of the bark surface layer was grated and homogenized for the analyses. Data analyses of the samples indicated variability in the element concentrations depending on the proximity and intensity of the emission sources. Furthermore, these results indicated four possible pollutants sources, those being, vehicular plus soil resuspension, industrial, marine aerosols and the tree bark composition itself. Enrichment factors obtained for the elements determined in tree barks indicated higher concentrations in samples collected in the MRSP than those obtained in the control regions. The As, Cd, Co, Pb and Zn concentrations found in tree barks presented an association with the concentrations of particulate matter (PM10) measured at the Environmental Company of the State of São Paulo (CETESB). In the following elements, Cl, Co, Mg and Ni found in tree barks there was a correlation with mortality rates due to cardiorespiratory diseases in adults. The findings of this study indicated the viability of the use of tree barks in air pollution studies of chemical elements, especially in those regions in which there is no air pollution monitoring network system.