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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Determinação de Co, Mo, Ni e V em material vegetal e solo por espectrometria de absorção atômica com fonte contínua e de alta resolução em forno de grafite empregando amostragem direta de sólidos / Determination of Co, Mo, Ni and V in plant material and soil by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis

Babos, Diêgo Victor de [UNESP] 18 July 2016 (has links)
Submitted by DIÊGO VICTOR DE BABOS null (diegobabos@hotmail.com) on 2016-08-08T23:38:08Z No. of bitstreams: 1 Dissertação Diêgo Babos.pdf: 1989792 bytes, checksum: 30376a94b5f5cac12b35744978cd6cc7 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-08-11T14:14:27Z (GMT) No. of bitstreams: 1 babos_dv_me_araiq_par.pdf: 1035449 bytes, checksum: 4a4c8a9a99f92024681ea27985b94b19 (MD5) / Made available in DSpace on 2016-08-11T14:14:27Z (GMT). No. of bitstreams: 1 babos_dv_me_araiq_par.pdf: 1035449 bytes, checksum: 4a4c8a9a99f92024681ea27985b94b19 (MD5) Previous issue date: 2016-07-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Avaliou-se a amostragem direta de sólidos como base de métodos analíticos simples, rápidos e mais limpos para determinar Co, Mo, Ni e V em tecido vegetal e solo empregando a espectrometria de absorção atômica de alta resolução com fonte contínua. Esta técnica foi escolhida devido as suas características peculiares, especialmente a elevada capacidade de correção de fundo. Na determinação de cobalto em material vegetal, a sobreposição espectral de SiO(g) na linha 240,725 nm do Co foi corrigida pelo método dos mínimos quadrados. Curvas de calibração (0–540 pg) com bons coeficientes de correlação lineares (R 0,9993) foram obtidas com padrões sólidos. O limite de detecção (LOD) foi 3 pg Co. Na determinação simultânea de Mo e Ni em material vegetal, empregou-se Co como padrão interno para Ni. Curvas de calibração (0,8-50 ng Ni; 0-0,33 ng Mo) lineares (R 0,9937) foram obtidas com padrões aquosos sem modificador químico. Os LODs foram 0,018 ng Mo e 0,025 ng Ni. A padronização interna aumentou a precisão das medidas para Ni de 62-135% para 94-105%. Vanádio e Co foram determinados em solos empregando NH4F como modificador. As calibrações, com padrões aquosos para V (0-40 ng), e por compatibilização de matriz para Co (0-5,0 ng), forneceram R 0,9979. Os LODs foram 0,044 ng Co e 0,43 ng V. Na determinação de Mo e Ni em solo, o modificador Mg(NO3)2 foi utilizado apenas para Ni. As curvas de calibração aquosas (0-500 ng Ni; 0-0,54 ng Mo) forneceram R 0,9953. Na determinação do Ni foi monitorado o tripleto em 341,377 nm, 341,347 nm e 341,394 nm, permitindo determinar Ni em ampla faixa de concentração. Os LODs foram 0,0082 ng Mo (313,259 nm), 0,021 ng Ni (341,477 nm),1,8 ng Ni (341,347 nm). A exatidão dos métodos foi avaliada via análise de materiais de referência certificados de solos e plantas. De uma forma geral, os resultados obtidos foram concordantes com os valores certificados ao nível de confiança de 95%. / High-resolution continuum source atomic absorption spectrometry with direct solid sampling was employed for the development of simple, fast and clean analytical methods for Co, Mo, Ni and V determination in soil and plant materials. The technique has as main advantages the efficiency to correct background absorption. For cobalt determination in plant material, a spectral overlap of SiO molecular absorption in Co line was corrected by using least squares background correction method. Calibration curves (0-540 pg) with correlation coefficients higher of 0.9993 were obtained with solid standards. The limit of detection was of 3 pg Co. For simultaneous determination of Mo and Ni in plant material Co was employed as internal standard for Ni. Calibration curves (0.8-50 ng Ni; 0-0.33 ng Mo) with correlation coefficients higher of 0.9937 were obtained with aqueous standards without chemical modifier. The LODs were 0.025 and 0.018 ng for Mo and Ni, respectively. The internal standardization increased the accuracy of Ni determinations from 62-135% to 94-105%. For V and Co determinations in soils the NH4F was used as chemical modifier. The calibration with aqueous standards for V (0-40 ng), and compatibility matrix for Co (0-5.0 ng), provided linear correlation coefficients better of 0.9979. The LODs were 0.044 and 0.43 ng for Co and V, respectively. For Mo and Ni determination in soil the Mg(NO3)2 was used as chemical modifier for Ni. The aqueous calibration curves (0-500 ng Ni; 0-0.54 ng Mo) provided linear correlation coefficients higher of 0.9953. For Ni determination were used the triplet lines at 341.377 nm, 341.347 nm and 341.394 nm, allowing the determination of Ni in wide concentration range. The calculated LODs were 0.0082 ng Mo (313.259 nm), 0.021 ng Ni (341.477 nm), 1.8 ng Ni (341.347 nm). The accuracy of the proposed methods was assessed by analysis of certified reference materials of soils and plants. In general, the results were in agreement with the certified values at 95% confidence level (t-test).
122

Desenvolvimento de m?todo para determina??o de cloro em petr?leo via mol?cula MgCl por HR-CS MAS

Oliveira, Izabel Kaline da Silva 28 July 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-01-24T12:15:33Z No. of bitstreams: 1 IzabelKalineDaSilvaOliveira_TESE.pdf: 1323354 bytes, checksum: 0c2134eae1c9170e6277290fc8a4b9da (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-01-26T13:30:04Z (GMT) No. of bitstreams: 1 IzabelKalineDaSilvaOliveira_TESE.pdf: 1323354 bytes, checksum: 0c2134eae1c9170e6277290fc8a4b9da (MD5) / Made available in DSpace on 2018-01-26T13:30:04Z (GMT). No. of bitstreams: 1 IzabelKalineDaSilvaOliveira_TESE.pdf: 1323354 bytes, checksum: 0c2134eae1c9170e6277290fc8a4b9da (MD5) Previous issue date: 2017-07-28 / Ag?ncia Nacional de Petr?leo - ANP / O cloreto ? considerado um dos principais contaminantes do petr?leo, pois interfere no processo de transporte e refino e pode ser transferido para os produtos derivados finais. Durante o refino, a presen?a de cloreto pode levar a forma??o de HCl, causando s?rios problemas de corros?o. Nesse sentido, foi desenvolvida uma metodologia para determina??o de cloro em amostras de petr?leo, preparadas sob a forma de emuls?es, por espectrometria de absor??o molecular de alta resolu??o com fonte cont?nua atrav?s da mol?cula diat?mica MgCl no comprimento de onda 377,01 nm. O preparo da emuls?o foi otimizado atrav?s de um planejamento experimental Centroid-Simplex. As condi??es ?timas de preparo das emuls?es foram: 0,5mL HNO3 5% (v/v), 0,5mL de xileno e 2 mL de uma mistura dos solventes n-Propanol/ Triton X-100 na propor??o 5:1. A massa de amostra de petr?leo foi de cerca de 0,20g. Magn?sio foi usado como precursor da mol?cula de MgCl, e a concentra??o otimizada foi de 10 g L-1. Os estudos da propor??o entre Mg e Cl para favorecimento da forma??o da mol?cula mostraram que para garantir a m?xima forma??o da mol?cula de MgCl ? necess?rio utilizar uma raz?o em massa de pelo menos 500 Mg:1 Cl. Uma massa de 5 ?g de Pd foi introduzida ? cada ciclo de inje??o como modificador qu?mico, para aumentar a estabilidade t?rmica da esp?cie molecular. As temperaturas de pir?lise e vaporiza??o otimizadas foram 800 ?C e 2300 ?C, respectivamente. Para an?lise de cloro, foram utilizadas oito amostras de petr?leo da Bacia Potiguar e dois materiais de refer?ncia certificados, ?leo lubrificante aditivado (NIST 1848) e a de ?leo combust?vel (NIST 1634c), foram utilizados para a verifica??o da exatid?o do m?todo. A estrat?gia de calibra??o contra padr?es aquosos foi poss?vel, obtendo-se o LOD de 5 mg kg-1. Testes de adi??o/recupera??o foram realizados e os valores obtidos ficaram na faixa entre 92 e 117%. A metodologia proposta mostra-se simples, r?pida com preparo de amostra simplificado. / Chloride is considered an important contaminant of petroleum as it interferes with the process of transportation and refining and can be transferred to the final product derivatives. During refining, the presence of chloride may lead to the formation of HCl, causing serious corrosion problems. A methodology for the determination of chlorine in petroleum samples prepared by emulsions was developed by high resolution molecular absorption spectrometry with continuum source through the diatomic molecule MgCl, in the wavelength 377.01 nm. The preparation of the emulsion was optimized through centroid-simplex design. The conditions of preparation of the emulsions were: 0.5 mL of 5% (v / v) HNO3, 0.5 mL of xylene and 2 mL of a mixture of n-Propanol / Triton X-100 solvents in the ratio 5:1. The crude oil mass used was about 0.20 g. Magnesium was used as the precursor of the molecule, the optimized concentration was 10 g L-1. The proportional studies between Mg and Cl for the formation of molecules show that to ensure the formation of a MgCl molecule is required for a mass ratio of at least 500 Mg: 1 Cl. A mass of 5 ?g of Pd was introduced at each cycle that chemical modifier for increase the thermal stability of the molecular species. The optimized pyrolysis and vaporization temperatures were 800 ? C and 2300 ? C, respectively. For chlorine analysis, eight crude oil samples from the Potiguar Basin and two certified reference materials, lubricated oil (NIST 1848) and fuel oil (NIST 1634c) were used, to verify the accuracy of the method. The calibration strategy against aqueous standards was possible, obtaining the LOD of 5 mg kg-1. Addition / recovery tests were performed and the values obtained were between 92 and 117%, values acceptable analytically. The proposed methodology is simple, fast with simplified sample preparation.
123

Desenvolvimento de métodos analíticos para avaliação da presença de elementos essenciais e potencialmente tóxicos em fórmulas infantis

Gamela, Raimundo Rafael January 2017 (has links)
O consumo de fórmulas infantis no Brasil, utilizadas como substituto do leite materno, tem aumentado nos últimos anos de forma significativa. Tal fato é uma preocupação para os órgãos de saúde pois, o aleitamento materno exclusivo até no mínimo 6 meses, deixou de fazer parte de nutrição da maioria dos lactentes. Os produtos utilizados como substituto do leite materno contêm quantidades suficientes de vitaminas e nutrientes que ajudam no desenvolvimento normal do organismo dos lactentes. Entretanto, além de elementos essenciais, podem conter elementos potencialmente tóxicos presentes na matéria prima ou oriundos das etapas de processamento e armazenamento das mesmas. No presente trabalho foram desenvolvidos métodos analítico para determinar a presença de elementos potencialmente tóxicos (As, Cd, Pb e Tl) e essenciais (Cu e Mn) em fórmulas infantis, utilizando espectrometria de absorção atômica de alta resolução com fonte contínua e forno de grafite e análise direta de sólidos. As amostras utilizadas neste trabalho foram obtidas nos mercados da cidade de Porto Alegre, RS, Brasil, todas na forma sólida (pó) com diferentes composições e matéria prima (arroz, aveia, soja e leite). As curvas de calibração foram realizadas com soluções padrão aquosas e os métodos otimizados foram aplicados nas amostras em estudo. Em todas as amostras os elementos As, Cd, Pb e Tl apresentaram valores de concentração abaixo do limite de detecção. Das seis amostras analisadas, três apresentaram valores de concentração de Cu abaixo dos parâmetros mínimos estabelecidos pela legislação brasileira, enquanto que para o Mn todas amostras apresentaram valores de concentração dentro dos parâmetros mínimos da legislação brasileira. Os métodos desenvolvidos foram simples, exatos e precisos, podendo ser utilizados para análise de rotina. / The consumption of infant formula in Brazil, as a replacement of breast milk, has lately increased significantly. It is a major concern for health agencies because the exclusive breastfeeding up to at least 6 months is no longer part of most infants. The products used as a substitute of the breast milk contain sufficient amounts of vitamins and nutrients, which helps in the normal development of the infants. However, besides the essential elements, it may contain potentially toxic elements present in raw material or from of the processing and storage stages of the same. In the present work the presence of the essential (Cu e Mn) and potentially toxic elements (As, Cd, Pb e Tl) in infant formulas were evaluated. For this, analytical methods were developed for the determination of As, Cd, Cu, Mn, Pb and Tl using high-resolution continnum source graphite furnace atomic absorption spectrometry and direct solid sampling analysis in infant formulas. The samples were acquired in Porto Alegre’s market, RS, Brazil, all in powder form with different compositions and raw materials (rice, oats, soy and bovine milk). The calibration curves were performed with aqueous standard solutions and the optimized methods were applied in the study samples. In all samples, the concentration values of As, Pb, Cd and Tl were below of the limit of detection. For the analyzed samples, three of them present the concentration values of Cu lower than the minimum parameters established by Brazilian legislation, while for Mn, all samples present the concentration values within the minimum parameters of Brazilian legislation. The developed methods for the determination of these elements in infant formulas were simple, exacts and precise, and can be applicated for the routine analysis.
124

Recipientundersökning av Ensjön : Bedömning av sulfidmalmgruvan Enåsens eventuella påverkan på sjöns vattenkvalitet

Enmark, Gustav January 2007 (has links)
Ensåsengruvan is a mine situated within Ljusdals municipality in central Sweden. Themine was in use from 1984 to 1991 and has since been undergoing a remediation program. Mine tailings from sulfide rich ore is a potential environmental hazard due to its tendency to cause acid waters and heavy metal leakage. Lake Ensjön is situated one kilometer from the mine area. Due to the hydrological conditions it was not expected to receive inflowing water from the mining area. A study done in 2005 showed high amounts of heavy metals in the lake. In this study water and sediments was analyzed to confirm the results from the 2005 study. Water was sampled two times during summer 2006 from the lake and adjoining streams. Sediment samples were collected with a core sampler at ten different locations within the lake. The water and sediment samples were analyzed for heavy metal content. Sub-samples from different depths in the sediment core were extracted so that conclusions on the contamination history could be drawn. The sediments were dated trough Cs-137 analyses. The depth in the profile with the highest Cs-137 content can be dated to the time of the Chernobyl fallout (1986). After dating, relevant samples were analyzed for metal content. The results show that Ensjön is contaminated by a local source. The surface sediments are high in copper, zinc, nickel and cadmium content. The content is high both compared to the samples from deeper in the sediment core and the surface sediments analyzed in the reference study done in 1980. The amounts of heavy metals are also high relative to the standards set by the Swedish Environmental Protection Agency. The water from the stream adjoining the lake from the mining area is high in content of the previously mentioned metals. The methods used, including sediment dating and metal analyses together with water analyses, has proven to be useful in investigating a suspected contamination from a point source. It can be concluded that Lake Ensjön is contaminated with water from the mine waste. No other sources in the catchment area can be the source of the enriched amounts of heavy metals. Focus should in further work be put upon finding the exact source of leakage from the mining area. / Från Enåsengruvan i Ljusdals kommun utvanns ur sulfidmalm guld, silver och koppar under åren 1984 till 1991. Avfall från sulfidmalmsgruvor medför miljöproblem genom försurning och läckage av tungmetaller. Vanligtvis täcks avfallet med jordmassor eller vatten för att förhindra påverkan på naturen. De studier som genomfördes under prospekteringen visade på att Ensjön, som är belägen inom en kilometers avstånd från gruvområdet, inte skulle påverkas av gruvan men en provtagning under 2005 visade på höga halter av tungmetaller i sjön. I denna studie har Ensjöns vattenkvalitet undersökts genom vatten och sedimentanalyser. Vattenprover i sjön och dess inlopp togs två gånger under sommaren 2006 och sedimentprover togs vid ett tillfälle på tio olika lokaler i sjön. En djupprofil av sedimenten analyserades för att föroreningshistoriken från innan gruvan togs i bruk till nutid skulle kunna kartläggas. För att datera sedimenten analyserades de med avseende på Cs-137. De högsta halterna av Cs-137 kan härledas till nedfallet från Tjernobylolyckan 1986. Efter datering valdes lämpliga prover ut för metallanalys. Resultaten visar på förhöjda halter av koppar, zink, nickel och kadmium. Halterna i ytsedimenten är höga både jämfört med de halter som återfinns på större djup i sedimentprofilen, motsvarande avsättning innan gruvdriften och vad som uppmättes i referensstudien från 1980. Halterna är även höga relativt de jämförvärden som Naturvårdsverket satt upp. Vattenanalyserna visar på att vattnet i inflödet från gruvområdet innehåller höga halter av de tidigare nämnda metallerna. Metoden med Cs-137-datering och analys med avseende på metaller av sediment har visat sig fungera väl för kartläggning av en nutida förorening från en punktkälla. Tillsammans med kompletterande vattenprover ger det en bra bild av den rådande situationen. Då resultaten visar att Ensjöns vatten är påverkat av en punktkälla och alla andra källor kan uteslutas får det anses klarlagt att sjöns vatten är påverkat av dränagevatten från gruvområdet. Fortsatta studier bör fokusera på att klarlägga den exakta källan till läckaget från gruvområdet.
125

Alfabetización inicial y emergente en niños y niñas de 3 años a 4 años 11 meses que asisten al jardín infantil : una propuesta de intervención en el aula bajo el enfoque de la psicogénesis de la lengua escrita.

Sívoli Henríquez, Yasna January 2007 (has links)
No description available.
126

Le conditionnement évaluatif reconsidéré à travers une approche intégrative et continue à multiples processus / evaluative conditioning reconsidered through an integrative and continuous multiple processes approach

Bouy, Julien 18 December 2014 (has links)
Résumé : Le Conditionnement Évaluatif (CE) réfère au changement évaluatif d'un Stimulus Neutre (SN) à l'issue des co-expériences relationnelles répétées de celui-ci avec un Stimulus Affectivement signifiant (SA). Les nombreuses divergences empiriques observées dans la littérature suggèrent, d'une part, que des distinctions fonctionnelles sont à faire entre les effets mis en évidence, et d'autre part, que des processus de différente nature puissent intervenir ou être impliqués selon les effets considérés. Ce travail de thèse propose de reconsidérer la variabilité fonctionnelle du CE à travers une approche à multiples processus intégrative et continue, se distinguant des approches à multiples processus du CE classiques sur plusieurs points majeurs, dont : (i) la perspective d'un continuum entre les différents effets ; (ii) la définition et la fonction conférées aux processus associatifs et élaboratifs, envisagés sous-tendre le CE ; (iii) la relation entre ces processus ; et (iv) la nature des contenus mémorisés. Afin de développer ces aspects, nous nous appuierons sur trois points du continuum envisagé (i.e., effets de CE directs, indirects « automatisés », et indirects inférentiels), sachant que chacun de ces points illustrent des effets caractérisés par une émergence plus ou moins automatique, coûteuse, consciente, et/ou contrôlée. La validité empirique de cette approche a été examinée par la mise à l'épreuve des hypothèses concernant la variabilité potentielle dans la facilité de manifestation des effets de CE indirects. À ce titre, 4 expériences ont été effectuées en vue de démontrer que l'émergence d'un CE indirect peut être plus ou moins favorisée selon le degré de propriétés partagées entre le SN et le SA d'un couple donné. Conformément à nos attentes, les résultats obtenus suggèrent que la manifestation d'un CE peut être privilégiée par le partage élevé de propriétés SN-SA. Nous discuterons de la contribution de ces résultats pour l'approche proposée, et plus largement à l'étude du CE. Par ailleurs, les limites méthodologiques et empiriques qui touchent l'ensemble des expériences réalisées, et les perspectives futures quant à l'approche « intégrative et continue » seront considérées. / Abstract: Evaluative Conditioning (EC) can be defined as an evaluative change of a neutral stimulus (i.e., the CS), resulting from the repeated relational experiences between this stimulus and a stimulus affectively significant (i.e., the US). Numerous studies conducted on EC revealed several inconsistent results. These inconsistencies underline that two important distinctions have to be considered. The first one deals with the type of EC effects obtained, either direct or indirect. The other one concerns the type of processes underlying EC effects, associative and elaborative ones. In this thesis, we propose an integrative and continuous approach of EC that takes into account these two distinctions, and offers new insight by considering a possible continuum between direct low-level associative effects and indirect high-level elaborative effects. This perspective differs notably from the multiples processes approach classically adopted in EC. The experimental validity of this “integrative and continuous” view was examined in 4 experiments, by testing the role of the specificity of the CS-US relationship on the facility for indirect EC to emerge. Precisely, we predict that CS-US relationship presenting a high level of common properties (e.g., semantic, perceptive, or lexical properties) leads to the emergence of indirect EC effect in a privileged way. As expected, we observed that CS-US relations that shared a high-level of common properties can generate stronger or exclusive EC effects compared to stimuli that showed low-level common properties. The contribution of these results for the “integrative and continuous” approach and for EC studies is discussed, along with their methodological and empirical limits. Finally, perspectives for the future of our approach are drawn.
127

Making a livable life in Manchester: doing justice to people seeking asylum

Pannett, Margaret Lorraine January 2011 (has links)
This thesis explores how people struggle to make livable lives in the conditions of existence of seeking asylum in the UK. The study is based on ethnographic research, conversations and participant observation, with people seeking asylum in Manchester. Grounding the research in their narratives is a contribution to decolonizing knowledge and doing justice to the sentience of people who are marginalized and pathologized. The narratives are brought into dialogue with feminist and decolonial philosophy and political theory, and with empirical studies of 'refugeedom' from a number of disciplines, to produce a new field of connection from which to map the terrain involved in theorizing livability. While the whole thesis seeks to respond to the narratives, there is a detailed focus on three dimensions which participants emphasize as crucial to livability: settlement in Manchester; the prohibition of employment; the asylum application procedures. These are moments in which livability is claimed as both ethics and practice. From the perspective of the narratives and the ethics which permeate them, livability opens up into questions of recognition, social justice and care. People claim commonality: recognition as human, equality and inclusion in social goods, and care in public settings. These are the practical and ethical supports of livability. The narratives point also towards critiques of 'refugeedom', the policies and practices that form the discursive and material conditions within which people seeking asylum attempt to make livable lives.
128

Výpočet zatížení a konstrukční návrh řízení / Load calculation and design of control system

Lontras, Martin January 2018 (has links)
This thesis deals with the control system of two-seater aircraft corresponding to CS-23 Level 2. First load calculations of each control surface are performed using the proses described in previous CS-23 regulation. This load is calculated trought the steering mechanism to control elements in cockpit. The resulting forces on the control elements are compared with the requi-rements in CS-23. Because the steering forces meets requirements is not necessary to propose changes in steering kinematics. However, there are further suggested ways of adjusting the control in case the external load would increase during further development of the airplane. At the end, the strength calculation of entire mechanism is preformed.
129

Koncepční návrh dvoumístného lehkého monitorovacího letounu / Conceptual study of light two-seater surveillance aircraft

Kaňák, Ondřej January 2012 (has links)
This master’s thesis deals with the conceptual design of light surveillance aircraft. It involves modifying of VUT 001 Marabu according to the new requirements, which has been mainly brought by new definition of typical flight. Also there is solved design and geometry surfaces of new aircraft. It contains design and computation of stand for electro-optical monitoring device. Last but not least are calculated important flight performances.
130

A Curriculum Development for 21st Century Learners: Using Project Based Learning toTeach the Four Cs Required for Today and Tomorrow's Workforce

Sheppard, Sarah 28 March 2022 (has links)
No description available.

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