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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.
1

Estudo das propriedades vibracionais do molibidato de sódio hidratado por espectroscopia Raman em função da pressão hidrostática / Study of the vibrational properties of the sodium molybdate dihydrate under pressure

Lima, Cleânio da Luz January 2008 (has links)
LIMA, Cleânio da Luz. Estudo das propriedades vibracionais do molibidato de sódio hidratado por espectroscopia Raman em função da pressão hidrostática. 2008. 87 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2008. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-06-09T18:03:35Z No. of bitstreams: 1 2008_dis_cllima.pdf: 1735905 bytes, checksum: a38aca9b6ecaf707ab1b6f24cdf68c3d (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-06-11T17:49:18Z (GMT) No. of bitstreams: 1 2008_dis_cllima.pdf: 1735905 bytes, checksum: a38aca9b6ecaf707ab1b6f24cdf68c3d (MD5) / Made available in DSpace on 2015-06-11T17:49:18Z (GMT). No. of bitstreams: 1 2008_dis_cllima.pdf: 1735905 bytes, checksum: a38aca9b6ecaf707ab1b6f24cdf68c3d (MD5) Previous issue date: 2008 / The molibidatos up a large class of inorganic compounds and have been the subject of several investigations. Usually the members of this family have Y2XO4.nH2O general formula, where Y = (Na, Ca), X = (Mo, S, W, Mn) with n = (0, 1, 3, 4...). The Na2MoO4.2H2O was studied through experiments of Raman spectroscopy aimed at investigating the effects of hydrostatic pressure on their properties structural and vibrational. The material Na2MoO4.2H2O experiencing a transition phase when the compressor is half the mixture of alcohols, this transition is structural. When the compressor is the way nujol (mineral oil) Na2MoO4.2H2O try the two-phase transitions. The difference for these events is that the Na2MoO4.2H2O interacts with the environment compressor alcohol, since the pressure to relax the spectrum of the material presents itself as being semidesidratrado not going back to the original phase. When the compressor means is the nujol, as well as an additional step, the Na2MoO4.2H2O, in the process of relaxation, restores the original phase, where the interim stage is deleted due to the effect of hysteresis. Therefore, it identifies three distinct phases in Na2MoO4.2H2O, in a range of 0 to 3.0 GPa (phase α), another between 3.0 and 4.0 GPa (phase δ) and third over 4.0 GPa (phase β). The first transition from phase α to phase δ is a conformal transition, due to distortions in tetraedros MoO4, leaving the group of symmetry D2h 15. The second transition is a structural transition due to the collapse of two modes in a single event, especially in the modes of the network, which indicates a transition to a structure for greater symmetry than the previous (possibly of the orthorhombic for tetragonal). / Os molibidatos constituem uma grande classe de compostos inorgânicos e têm sido o objeto de várias investigações, devido o estudo ainda não realizado no mesmo usando espectroscopia Raman em função da pressão e as diversas aplicabilidades em diversos campos de estudos do Na2MoO4.2H2O nos motivamos a realiza este estudo. Geralmente os membros desta família possuem fórmula geral Y2XO4.nH2O, onde Y = (Na, Ca), X = (Mo, S, W, Mn) com n = (0, 1, 3, 4...). O Na2MoO4.2H2O foi estudado através de experimentos de espectroscopia Raman visando investigar os efeitos da aplicação de pressão hidrostática em suas propriedades estruturais e vibracionais. Na célula de pressão (DAC, do inglês Diamond Anvil Cell, que permite a obtenção de pressão de 0-10GPa) foram utilizados como meios compressores uma mistura de álcoois (metanol e etanol na proporção de 4:1) e óleo mineral (Nujol). O material Na2MoO4.2H2O experimenta uma transição de fase quando o meio compressor é a mistura de álcoois, sendo esta transição estrutural. Já quando o meio compressor é o nujol (óleo mineral) o Na2MoO4.2H2O experimenta duas transições de fase. A diferença para tais acontecimentos é que o Na2MoO4.2H2O interage com o meio compressor álcool, uma vez que ao relaxar-se a pressão o espectro do material apresenta-se como se estivesse semidesidratrado não voltando para a fase original (fase α). Quando o meio compressor é o nujol, além de uma fase adicional, o Na2MoO4.2H2O, no processo de relaxamento, recupera a fase original, sendo que a fase intermediária é suprimida devido ao efeito de histerese. Portanto, identificam-se três fases distintas no Na2MoO4.2H2O, uma no intervalo de 0 a 3,0 GPa (fase α), outra entre 3,0 e 4,0 GPa (fase δ) e a terceira acima de 4,0 GPa (fase β). A primeira transição da fase α para a fase δ é uma transição conformacional, devido a distorções nos tetraedros MoO4, saindo do grupo de simetria D2h15. A segunda transição é uma transição estrutural devido ao colapso de dois modos em um único modo, principalmente na região dos modos da rede, o que indica uma transição para uma estrutura de maior simetria que a anterior (possivelmente de ortorrômbica para tetragonal).
2

Chemical aspects of human plaque and enamel

Grobler, Sias Renier January 1982 (has links)
Philosophiae Doctor - PhD / The ideal conditions for the use of hydrazinium sulphate as a reducing agent to determine phosphorus in dental plaque were investigated. When this method was compared to the tin (II) chloride (Kuttner and Cohen, 1927) and ascorbic acid method (Chen, loribara and Warner, 1956),which is generally in use for the measurement of phosphorus in plaque, it was found to have certain advantages. Different ashing techniques were compared, as well as the influence of different acids on wet ashing. The hydrazinium sulphate method could determine as little as 1,8 ~g phosphorus per 50 ml and is recommended for the routine analysis of phosphorus in dental plaque samples with wet ashing. Today phosphorus can be determined, among other methods gravimetrically, titrimetically and spectroscopically (Williams, 1979). Through spectroscopic methods phosphate might be analysed spectrophotometrically by 3 main methods, as molybdophosphoric acid, its reducing product molybdenum blue and the yellow vanadomolybdophosphoric complex (Stuart and Duff, 1980). In addition indirect methods derived from molybdophosphoric acid might also be used (Williams, 1979). When phosphorus is spectrophotometrically determined during the reduction of a phosphomolybdate complex by means of different reducing agents (Kuttner and Cohen, 1927; Chen et aI, 1956; Fiske and Subbarow, 1925 and 1929, Taylor and Miller, 1914; Martin and Doty, 1949; Eibl and Lands, 1969; Vogel, 1961; Boltz and Mellong, 1947; Lazarus and Chou, 1972; Laws and Webley, 1959; Burton and Riley, 1955; Dickman and Bray, 1940), it is necessary to establish the optimum conditions under which the reducing agent, hydrazinium sulphate, can be used. In spite of this, many details about exact experimental procedures are not known (Taylor and Miller, 1914; Vogel, 1961; Boltz and Mellon, 1947). The present investigation is an attempt to establish the ideal conditions for the use of hydrazinium sulphate as a reducing agent during the formation of molybdenum blue (Schirmer et al, 1942) and the effectiveness of the method for the determination of phosphorus in dental plaque by different ashing techniques. The hydrazine method is also compared to that of Chen et al (1956) which is generally in use for plaque phosphate determinations by many authors (Ashley, 1975; Ashley and Wilson, 1976; Kleinberg et al, 1971; Zuniga et al, 1973), as well as to the sometimes used (Dawes and Jenkins, 1962) tin (II) chloride method of Kuttner and Cohen (1927). For the review of many other accepted methods, see Lindberg and Ernster (1956), and Williams (1979). The results are compared to the modified ascorbic acid method (Chen et al, 1956) as well as to the tin (II) chloride method (Kuttner and Cohen, 1927).
3

Estudo das propriedades vibracionais do molibidato de sÃdio hidratado por espectroscopia Raman em funÃÃo da pressÃo hidrostÃtica / Study of the vibrational properties of the sodium molybdate dihydrate under pressure

CleÃnio da Luz Lima 18 July 2008 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Os molibidatos constituem uma grande classe de compostos inorgÃnicos e tÃm sido o objeto de vÃrias investigaÃÃes, devido o estudo ainda nÃo realizado no mesmo usando espectroscopia Raman em funÃÃo da pressÃo e as diversas aplicabilidades em diversos campos de estudos do Na2MoO4.2H2O nos motivamos a realiza este estudo. Geralmente os membros desta famÃlia possuem fÃrmula geral Y2XO4.nH2O, onde Y = (Na, Ca), X = (Mo, S, W, Mn) com n = (0, 1, 3, 4...). O Na2MoO4.2H2O foi estudado atravÃs de experimentos de espectroscopia Raman visando investigar os efeitos da aplicaÃÃo de pressÃo hidrostÃtica em suas propriedades estruturais e vibracionais. Na cÃlula de pressÃo (DAC, do inglÃs Diamond Anvil Cell, que permite a obtenÃÃo de pressÃo de 0-10GPa) foram utilizados como meios compressores uma mistura de Ãlcoois (metanol e etanol na proporÃÃo de 4:1) e Ãleo mineral (Nujol). O material Na2MoO4.2H2O experimenta uma transiÃÃo de fase quando o meio compressor à a mistura de Ãlcoois, sendo esta transiÃÃo estrutural. Jà quando o meio compressor à o nujol (Ãleo mineral) o Na2MoO4.2H2O experimenta duas transiÃÃes de fase. A diferenÃa para tais acontecimentos à que o Na2MoO4.2H2O interage com o meio compressor Ãlcool, uma vez que ao relaxar-se a pressÃo o espectro do material apresenta-se como se estivesse semidesidratrado nÃo voltando para a fase original (fase α). Quando o meio compressor à o nujol, alÃm de uma fase adicional, o Na2MoO4.2H2O, no processo de relaxamento, recupera a fase original, sendo que a fase intermediÃria à suprimida devido ao efeito de histerese. Portanto, identificam-se trÃs fases distintas no Na2MoO4.2H2O, uma no intervalo de 0 a 3,0 GPa (fase α), outra entre 3,0 e 4,0 GPa (fase δ) e a terceira acima de 4,0 GPa (fase β). A primeira transiÃÃo da fase α para a fase δ à uma transiÃÃo conformacional, devido a distorÃÃes nos tetraedros MoO4, saindo do grupo de simetria D2h15. A segunda transiÃÃo à uma transiÃÃo estrutural devido ao colapso de dois modos em um Ãnico modo, principalmente na regiÃo dos modos da rede, o que indica uma transiÃÃo para uma estrutura de maior simetria que a anterior (possivelmente de ortorrÃmbica para tetragonal). / The molibidatos up a large class of inorganic compounds and have been the subject of several investigations. Usually the members of this family have Y2XO4.nH2O general formula, where Y = (Na, Ca), X = (Mo, S, W, Mn) with n = (0, 1, 3, 4...). The Na2MoO4.2H2O was studied through experiments of Raman spectroscopy aimed at investigating the effects of hydrostatic pressure on their properties structural and vibrational. The material Na2MoO4.2H2O experiencing a transition phase when the compressor is half the mixture of alcohols, this transition is structural. When the compressor is the way nujol (mineral oil) Na2MoO4.2H2O try the two-phase transitions. The difference for these events is that the Na2MoO4.2H2O interacts with the environment compressor alcohol, since the pressure to relax the spectrum of the material presents itself as being semidesidratrado not going back to the original phase. When the compressor means is the nujol, as well as an additional step, the Na2MoO4.2H2O, in the process of relaxation, restores the original phase, where the interim stage is deleted due to the effect of hysteresis. Therefore, it identifies three distinct phases in Na2MoO4.2H2O, in a range of 0 to 3.0 GPa (phase α), another between 3.0 and 4.0 GPa (phase δ) and third over 4.0 GPa (phase β). The first transition from phase α to phase δ is a conformal transition, due to distortions in tetraedros MoO4, leaving the group of symmetry D2h 15. The second transition is a structural transition due to the collapse of two modes in a single event, especially in the modes of the network, which indicates a transition to a structure for greater symmetry than the previous (possibly of the orthorhombic for tetragonal).
4

Control of anthracnose (caused by Colletotrichum gloeosporioides s.l.) on mango in Senegal by fungicides and biofungicides

Diallo, Yaya 15 June 2016 (has links)
Senegal ranks second for mango production among West African countries and has the potential to competitively produce mangoes for the European market. Colletotrichum gloeosporioides Penz. and Sacc. has historically been considered the causal pathogen of anthracnose of mango and other fruits, but is now known to represent a species complex. Field trials to examine the efficacy of fungicides and biofungicides were conducted in southern and northern production regions of Senegal. In three southern trials, Sonata (Bacillus pumilus strain QST 2808), Serenade Optimum (Bacillus subtilis strain QST 713), and sodium molybdate provided 63%, 67% and 76% control of disease severity, respectively, whereas thiophanate methyl and azoxystrobin provided 77% and 78% control, respectively. Disease severities of all treatments were significantly lower than that of the control. Thiophanate methyl and azoxystrobin produced more disease-free mangoes (64 and 62%, respectively) than Serenade (49%), sodium molybdate (44%), and Sonata (38%). Differences within each trial were not statistically significant, but when all trials were combined, all treatments resulted in significantly more disease-free mangoes than the control. Among treatments, thiophanate methyl and azoxystrobin resulted in significantly more disease-free mangoes than Sonata. No results were obtained in the northern orchards due to an absence of disease development. Sequencing of the ITS gene region of 30 Colletotrichum isolates from mangoes from different regions in Senegal indicated that all belonged to the C. gloeosporioides species complex. Sequencing of the ApMat intergenic region identified all of them as most closely resembling C. siamense. / Master of Science in Life Sciences
5

Estudo de inibidores de corros?o em concreto armado, visando a melhoria na sua durabilidade

Silva, Djalma Ribeiro da 01 March 2007 (has links)
Made available in DSpace on 2014-12-17T14:07:22Z (GMT). No. of bitstreams: 1 DjalmaRS.pdf: 1628891 bytes, checksum: d4993a3fdaeab8a1baca119c6780c3ac (MD5) Previous issue date: 2007-03-01 / Petr?leo Brasileiro SA - PETROBRAS / This thesis has as objective presents a methodology to evaluate the behavior of the corrosion inhibitors sodium nitrite, sodium dichromate and sodium molybdate, as well as your mixture, the corrosion process for the built-in steel in the reinforced concrete, through different techniques electrochemical, as well as the mechanical properties of that concrete non conventional. The addition of the inhibitors was studied in the concrete in the proportions from 0.5 to 3.5 % regarding the cement mass, isolated or in the mixture, with concrete mixture proportions of 1.0:1.5:2.5 (cement, fine aggregate and coarse aggregate), superplasticizers 2.0 % and 0.40 water/cement ratio. In the modified concrete resistance rehearsals they were accomplished to the compression, consistence and the absorption of water, while to analyze the built-in steel in the concrete the rehearsals of polarization curves they were made. They were also execute, rehearsals of corrosion potential and polarization resistance with intention of diagnose the beginning of the corrosion of the armors inserted in body-of-proof submitted to an accelerated exhibition in immersion cycle and drying to the air. It was concluded, that among the studied inhibitors sodium nitrite , in the proportion of 2.0 % in relation to the mass of the cement, presented the best capacity of protection of the steel through all the studied techniques and that the methodology and the monitoring techniques used in this work, they were shown appropriate to evaluate the behavior and the efficiency of the inhibitors / Esta tese tem como objetivo apresentar uma metodologia para avaliar o comportamento dos inibidores de corros?o nitrito de s?dio, molibdato de s?dio, dicromato de s?dio, bem como a suas misturas, no processo de corros?o para o a?o embutido no concreto armado, atrav?s de diferentes t?cnicas eletroqu?micas, bem como as propriedades mec?nicas desse concreto n?o convencional. Estudou-se a adi??o dos inibidores no concreto nas propor??es de 0,5 a 3,5 % em rela??o ? massa do cimento, isolados e em mistura, num tra?o 1,0:1,5:2,5 (cimento, areia e brita), superplastificante 2,0 % e rela??o ?gua/cimento 0,40. No concreto modificado foram realizados ensaios de resist?ncia ? compress?o, consist?ncia e a absor??o de ?gua, enquanto que para analisar o a?o embutido no concreto foram efetuados ensaios de curvas de polariza??o. Foram executados tamb?m ensaios de potencial de corros?o e resist?ncia de polariza??o com intuito de diagnosticar o in?cio da corros?o das armaduras inseridas em corpos-de-prova submetidos a uma exposi??o acelerada em ciclo de imers?o e secagem ao ar. Concluiu-se que, dentre os inibidores estudados, o nitrito de s?dio, na propor??o de 2,0 % em rela??o ? massa do cimento, apresentou a melhor capacidade de prote??o do a?o atrav?s de todas as t?cnicas estudadas e que a metodologia e as t?cnicas de monitoramento utilizadas neste trabalho mostraram-se adequadas para avaliar o comportamento e a efici?ncia dos inibidores
6

Tratamento de sementes de soja com molibdênio e inoculante: desempenho agronômico e atividade da nitrato redutase / Treatment of soybean seeds with molybdenum and inoculant: agronomic performance and activity of nitrate reductase

Gewehr, Ewerton 02 March 2015 (has links)
Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2018-07-03T17:08:29Z No. of bitstreams: 1 Dissertação Final Ewerton Gewehr.pdf: 999222 bytes, checksum: f1b7c9952c0b914fad5652702ae2a3c3 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-07-11T11:50:57Z (GMT) No. of bitstreams: 1 Dissertação Final Ewerton Gewehr.pdf: 999222 bytes, checksum: f1b7c9952c0b914fad5652702ae2a3c3 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-07-11T11:52:55Z (GMT) No. of bitstreams: 1 Dissertação Final Ewerton Gewehr.pdf: 999222 bytes, checksum: f1b7c9952c0b914fad5652702ae2a3c3 (MD5) / Made available in DSpace on 2018-07-11T12:00:29Z (GMT). No. of bitstreams: 1 Dissertação Final Ewerton Gewehr.pdf: 999222 bytes, checksum: f1b7c9952c0b914fad5652702ae2a3c3 (MD5) Previous issue date: 2015-03-02 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / O objetivo do trabalho foi analisar o efeito da aplicação do molibdênio associado ao inoculante via tratamento de sementes em soja e sua função nos caracteres agronômicos, qualidade fisiológica e atividade da enzima nitrato redutase. O experimento foi em delineamento de blocos casualizados em um modelo bifatorial com quatro repetições, onde o primeiro fator de tratamento foram as doses de molibdênio (Mo) utilizando como fonte molibdato de Sódio (solução 127g.L-1). As doses que constituíram os tratamentos foram: zero; 16; 32; 48; 64 g.100kg-1 de sementes combinadas com o segundo fator de tratamento que foi a presença e a ausência de inoculante, via tratamento de sementes em soja, no período de safra 2013/2014. No primeiro trabalho o experimento foi conduzido até a fase de maturação de campo, sendo posteriormente realizado a avalição dos caracteres agronômicos e a qualidade fisiológica das sementes produzidas. No segundo trabalho, durante a condução do experimento, foram realizadas coletas de folhas em diferentes estádios fenológicos para avaliação da atividade de enzima nitrato redutase. Os resultados das analise da atividade da nitrato redutase foi correlacionada com os dados de caracteres agronômicos e de qualidade fisiológica de sementes obtidos no primeiro capitulo. No primeiro trabalho, verificou-se, que a adição de inoculante proporciona uma melhora na qualidade fisiológica de sementes, em relação ao vigor das sementes produzidas, evidenciado uma maior porcentagem no teste de envelhecimento acelerado, além de proporcionar um aumento no comprimento e massa seca de parte aérea e de raiz. Também influenciou positivamente na altura de planta, numero de legumes por planta, numero de sementes por planta e peso de mil sementes. As sementes produzidas mediante a aplicação de molibdênio na semeadura, também promoveu benefícios no vigor das sementes, contribuindo para um crescimento linear do comprimento e massa seca de parte aérea e raiz, conforme o aumento da dose. Além disso, o aumento da dose de molibdênio afetou de forma benéfica os caracteres agronômicos, comprovando um maior peso de mil semente ao final do ciclo da cultura, e uma maior altura de planta. No segundo trabalho, verificou-se que o molibdênio com a presença de inoculante influencia positivamente na atividade da enzima nitrato redutase, tanto no estádio vegetativo como no reprodutivo. As doses de molibdênio sem a presença do inoculante proporcionam um aumento crescente da atividade da enzima nitrato redutase ate a maior dose (64 g Mo. 100 kg-1 de semente). A atividade da enzima nitrato redutase apresenta uma correlação positiva com os testes de vigor e com os caracteres agronômicos. / The objectives of this work were to analyze and compare the effects of molybdenum associated with inoculant as seed treatment in soybeans and its role in agronomic performance, physiological quality and nitrate reductase enzymeactivity . The experiment was arranged with in a randomized complete block design with four replications. The treatments were set up in a factorial design, where the first treatment factor were the doses of molybdenum (Mo) from source of sodium molybdate (127g.L-1 solution). The following doses were used: zero; 16; 32; 48; 64 g.100kg-1 and these doses were combined with the second seed treatment factor. Therefore, the second factor was the presence and absence of inoculant via soybean seed treatment in the crop season 2013/2014. In the first study, the experiment was conducted until crop maturation phase, and subsequently were performed evaluation of agronomic performance and physiological seed quality. In the second study, during the experiment, leaf samples were taken at different growth stages to evaluate the nitrate reductase enzyme activity. The results of nitrate reductase activity were correlated with the data of agronomic performance and physiological quality of seeds obtained in the first chapter. In the first study, it was found that the addition of inoculant provides an improvement in the physiological quality of seed vigor compared to seeds produced, increase percentage of germinated seeds in the accelerated aging test as well as providing an increase in the length and mass of shoot and root. Also had a positive effect on plant height, number of pods per plant, seed number per plant and thousand seed weight. The seeds produced by molybdenum application at sowing also promoted benefits in seed vigor, contributing to a linear increase in length and dry weight of shoot and root, with increasing dose. Furthermore, increasing doses of molybdenum provide beneficial effects on agronomic characters, showing a higher thousand seed weight at the end of the cycle, and a larger plant height. In the second study, it was found that molybdenum in the presence of inoculant show positive influence on the nitrate reductase enzyme activity in the vegetative and reproductive stages. The molybdenum doses without the presence of inoculant provide a growing increase in nitrate reductase activity up to the highest dose (64 g Mo. 100 kg-1 seed). The nitrate reductase activity show a positive correlation with vigor tests and agronomic characters.

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