• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 3
  • 2
  • 1
  • Tagged with
  • 11
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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

Efici?ncia de extra??o de cobre e n?quel utilizando sistemas microemulsionados bif?sicos e trif?sicos

Oliveira, M?nica Rodrigues de 23 January 2014 (has links)
Made available in DSpace on 2014-12-17T15:42:28Z (GMT). No. of bitstreams: 1 MonicaRO_TESE.pdf: 4155777 bytes, checksum: 6bff63b5cb0f37e64dfe6fcb144dae79 (MD5) Previous issue date: 2014-01-23 / The environmental impact due to the improper disposal of metal-bearing industrial effluents imposes the need of wastewater treatment, since heavy metals are nonbiodegradable and hazardous substances that may cause undesirable effects to humans and the environment. The use of microemulsion systems for the extraction of metal ions from wastewaters is effective when it occurs in a Winsor II (WII) domain, where a microemulsion phase is in equilibrium with an aqueous phase in excess. However, the microemulsion phase formed in this system has a higher amount of active matter when compared to a WIII system (microemulsion in equilibrium with aqueous and oil phases both in excess). This was the reason to develop a comparative study to evaluate the efficiency of two-phases and three-phases microemulsion systems (WII and WIII) in the extraction of Cu+2 and Ni+2 from aqueous solutions. The systems were composed by: saponified coconut oil (SCO) as surfactant, n-Butanol as cosurfactant, kerosene as oil phase, and synthetic solutions of CuSO4.5H2O and NiSO4.6H2O, with 2 wt.% NaCl, as aqueous phase. Pseudoternary phase diagrams were obtained and the systems were characterized by using surface tension measurements, particle size determination and scanning electron microscopy (SEM). The concentrations of metal ions before and after extraction were determined by atomic absorption spectrometry. The extraction study of Cu+2 and Ni+2 in the WIII domain contributed to a better understanding of microemulsion extraction, elucidating the various behaviors presented in the literature for these systems. Furthermore, since WIII systems presented high extraction efficiencies, similar to the ones presented by Winsor II systems, they represented an economic and technological advantage in heavy metal extraction due to a small amount of surfactant and cosurfactant used in the process and also due to the formation of a reduced volume of aqueous phase, with high concentration of metal. Considering the reextraction process, it was observed that WIII system is more effective because it is performed in the oil phase, unlike reextraction in WII, which is performed in the aqueous phase. The presence of the metalsurfactant complex in the oil phase makes possible to regenerate only the surfactant present in the organic phase, and not all the surfactant in the process, as in WII system. This fact allows the reuse of the microemulsion phase in a new extraction process, reducing the costs with surfactant regeneration / O impacto ambiental gerado pelo descarte de efluentes industriais carregados de metais pesados imp?e a necessidade do tratamento desses rejeitos, uma vez que s?o t?xicos e n?o biodegrad?veis, podendo causar s?rios danos ? popula??o e ao meio ambiente. O processo de extra??o de c?tions met?licos utilizando microemuls?es ? eficaz quando acontece em WII, onde a fase microemulsionada encontra-se em equil?brio com uma fase aquosa em excesso. No entanto, a microemuls?o formada nesse sistema possui uma maior quantidade de mat?ria ativa quando comparada ao equil?brio de WIII (microemuls?o em equil?brio com fases aquosa e oleosa, ambas em excesso), ainda pouco estudado, motivando, assim, o desenvolvimento de um estudo comparativo da efici?ncia de extra??o dos ?ons Cu2+ e Ni2+ por sistemas microemulsionados bif?sicos e trif?sicos (WII e WIII). Os constituintes utilizados nos sistemas de extra??o foram: ?leo de coco saponificado - OCS (Tensoativo), n- Butanol (Cotensoativo), querosene (Fase Oleosa) e solu??es sint?ticas de CuSO4.5H2O e NiSO4.6H2O com NaCl 2% (fases aquosas). Foram obtidos os diagramas de fases pseudotern?rios e os sistemas microemulsionados foram caracterizados atrav?s das t?cnicas de tens?o superficial, tamanho de part?culas e microscopia eletr?nica de varredura (MEV). A concentra??o dos ?ons foi determinada por espectrometria de absor??o at?mica. O estudo da extra??o dos c?tions met?licos Cu2+ e Ni2+ na regi?o de WIII contribuiu para um melhor entendimento dos processos de extra??o por microemuls?o, elucidando os v?rios comportamentos apresentados na literatura para esses sistemas. Al?m disso, uma vez que houve uma alta efici?ncia de extra??o, similar aos sistemas de Winsor II, o sistema trif?sico (WIII), por apresentar uma menor quantidade de tensoativo e cotensoativo, e um menor volume de fase aquosa ap?s a extra??o, levou a uma maior concentra??o do metal, representando uma vantagem econ?mica e tecnol?gica do processo. Assim, a extra??o em sistema trif?sico ? vi?vel e, apesar dos percentuais de extra??o em WII e WIII serem semelhantes, o sistema de WIII leva a uma maior concentra??o do metal na fase extrato. O presente trabalho mostrou, ainda, que a etapa de reextra??o para os sistemas em WIII ? mais eficaz pois, diferentemente da extra??o em Winsor II, ela ? realizada na fase oleosa, onde est? depositado o complexo metal/tensoativo, regenerando somente o tensoativo que complexa com o metal na fase org?nica, e n?o todo o tensoativo utilizado, como ? o caso do equil?brio em Winsor II. Este fato viabiliza a reutiliza??o da fase microemuls?o no processo de extra??o, diminuindo os custos de regenera??o do tensoativo
2

Lines That Move: Winsor McCay's Work in Performance and Comics, 1900-1920

Wikoff, Brian W. 18 August 2009 (has links)
No description available.
3

A study of the dividend decision and investment decision of a sample of Hong Kong corporations /

Au, Kwok-han. January 1982 (has links)
Thesis (M.B.A.)--University of Hong Kong, 1982.
4

A study of the dividend decision and investment decision of a sample of Hong Kong corporations

Au, Kwok-han. January 1982 (has links)
Thesis (M.B.A.)--University of Hong Kong, 1982. / Also available in print.
5

Desenvolvimento de metodologia de extra??o e pr?-concentra??o utilizando sistema microemulsionado para determina??o de Cd, Co, Cu, Ni, Pb e Tl em ?guas naturais e produzidas por HR-CS AAS

Costa, Emily Cintia Tossi de Ara?jo 23 September 2013 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-02-01T21:27:07Z No. of bitstreams: 1 EmilyCintiaTossiDeAraujoCosta_TESE.pdf: 2216846 bytes, checksum: 5f38e382d8ae3c1bfe9f3db58b62a672 (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2016-02-02T21:24:40Z (GMT) No. of bitstreams: 1 EmilyCintiaTossiDeAraujoCosta_TESE.pdf: 2216846 bytes, checksum: 5f38e382d8ae3c1bfe9f3db58b62a672 (MD5) / Made available in DSpace on 2016-02-02T21:24:40Z (GMT). No. of bitstreams: 1 EmilyCintiaTossiDeAraujoCosta_TESE.pdf: 2216846 bytes, checksum: 5f38e382d8ae3c1bfe9f3db58b62a672 (MD5) Previous issue date: 2013-09-23 / A contamina??o de ?guas naturais por metais tornou-se assunto de interesse p?blico mundial por serem considerados biocumulativos. A determina??o e o monitoramento de contaminantes met?licos em ?guas ? uma tarefa que deve ser cont?nua e por isto a import?ncia do desenvolvimento, modifica??o e otimiza??o de metodologias anal?ticas capazes de realizar a determina??o dos v?rios contaminantes met?licos em ambientes naturais, pois em muitos casos, a instrumenta??o dispon?vel n?o apresenta sensibilidade anal?tica suficiente para a determina??o de tra?os. Neste estudo, um m?todo de extra??o e pr?-concentra??o utilizando um sistema microemulsionado, no equil?brio de Winsor II foi testado e otimizado para a determina??o dos metais Co, Cd, Pb, Tl, Cu e Ni por Espectrometria de absor??o at?mica de alta resolu??o com fonte cont?nua e atomiza??o em forno de grafite e chama (HR-CS AAS). A otimiza??o do programa de temperatura para o forno de grafite foi realizada atrav?s de curvas de pir?lise e atomiza??o para cada analito sem e com o uso de diferentes modificadores qu?micos. Cd e Pb tiveram condi??es ?timas com modificador permanente Ru, pir?lise em 700?C e atomiza??o em 1700?C, para Tl solu??o Pd/Mg foi o melhor modificador, temperaturas 600?C e 1700?C de pir?lise e atomiza??o, respectivamente e para o Co pir?lise em 800?C e atomiza??o ? 2400?C sem uso de modificador qu?mico, por?m W foi empregado como modificador permanente a fim de se prolongar o tempo de vida ?til do forno. Cu e Ni foram analisados na chama ap?s pr?-concentra??o. Avaliou-se tamb?m fatores que influenciam a efici?ncia de extra??o, atrav?s do efeito salting out. Como compromisso, 6 g L-1 de Na e 1% de HNO3 (v/v) foi definido. Para determina??o do ponto ?timo de extra??o, um planejamento centroide-simplex foi aplicado, sendo escolhido como compromisso as seguintes propor??es: 70% fase aquosa, 10% fase ?leo e 20% Cotensoativo/Tensoativo (C/T = 4). Ap?s extra??o, os metais foram determinados e as Figuras de m?rito obtidas para o m?todo proposto foi: 0,1 a 10 ?g L-1 de faixa linear, LOD 0,094, 0,011, 0,057 e 0,050 ?g L-1 para Pb, Cd, Tl e Co, respectivamente. Testes de adi??o e recupera??o na amostra certificada apresentaram valores de recupera??o ap?s extra??o de 105 e 101% para Pb e Cd, respectivamente, e nas amostras fortificadas a recupera??o para os analitos ficou entre 107 e 108% comprovando que o m?todo proposto pode ser utilizado na extra??o, possibilitou a separa??o dos metais de matrizes complexas, e ainda com bom fator de pr?-concentra??o. / The determination and monitoring of metallic contaminants in water is a task that must be continuous, leading to the importance of the development, modification and optimization of analytical methodologies capab le of determining the various metal contaminants in natural environments, because, in many cases, the ava ilable instrumentation does not provide enough sensibility for the determination of trace values . In this study, a method of extraction and pre- concentration using a microemulsion system with in the Winsor II equilibrium was tested and optimized for the determination of Co, Cd, P b, Tl, Cu and Ni through the technique of high- resolution atomic absorption spectrometry using a continuum source (HR-CS AAS). The optimization of the temperature program for the graphite furnace (HR-CS AAS GF) was performed through the pyrolysis and atomization curves for the analytes Cd, Pb, Co and Tl with and without the use of different chemical modifiers. Cu and Ni we re analyzed by flame atomization (HR-CS F AAS) after pre-concentr ation, having the sample introduction system optimized for the realization of discrete sampling. Salinity and pH levels were also analyzed as influencing factors in the efficiency of the extraction. As final numbers, 6 g L -1 of Na (as NaCl) and 1% of HNO 3 (v/v) were defined. For the determination of the optimum extraction point, a centroid-simplex statistical plan was a pplied, having chosen as the optimum points of extraction for all of the analytes, the follo wing proportions: 70% aqueous phase, 10% oil phase and 20% co-surfactant/surfactant (C/S = 4). After extraction, the metals were determined and the merit figures obtained for the proposed method were: LOD 0,09, 0,01, 0,06, 0,05, 0,6 and 1,5 ?g L -1 for Pb, Cd, Tl, Co, Cu and Ni, re spectively. Line ar ranges of ,1- 2,0 ?g L -1 for Pb, 0,01-2,0 ?g L -1 for Cd, 1,0 - 20 ?g L -1 for Tl, 0,1-5,0 ?g L -1 for Co, 2-200 ?g L -1 and for Cu e Ni 5-200 ?g L -1 were obtained. The enrichment factors obtained ranged between 6 and 19. Recovery testing with the certified sample show ed recovery values (n = 3, certified values) after extraction of 105 and 101, 100 and 104% for Pb, Cd, Cu and Ni respectively. Samples of sweet waters of lake Jiqui, saline water from Potengi river and water produced from the oil industry (PETROBRAS) were spiked and the recovery (n = 3) for the analytes were between 80 and 112% confirming th at the proposed method can be used in the extraction. The proposed method enabled the sepa ration of metals from complex matrices, and with good pre-concentration factor, consistent with the MPV (allowed limits) compared to CONAMA Resolution No. 357/2005 which regulat es the quality of fresh surface water, brackish and saline water in Brazil.
6

Sistemas microemulsionados aplicados ? remo??o da cor de efluente t?xtil

Beltrame, Leoc?dia Terezinha Cordeiro 21 October 2006 (has links)
Made available in DSpace on 2014-12-17T15:01:57Z (GMT). No. of bitstreams: 1 LeocadiaTCB.pdf: 1594369 bytes, checksum: da7a2bc5860922178cae36e104bfbd40 (MD5) Previous issue date: 2006-10-21 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Effluent color resulting from textile dyeing processes has been one of the biggest environmental problems faced by the textile industry. In particular, reactive dyes are highly resistant to conventional wastewater treatment methods. New technologies have been contemplated, some of which have been applied in industrial treatment plants, but color removal has not been efficiently attained. Since microemulsion systems provide good results in heavy metals and proteins extraction processes, their use in dyes extraction has been suggested and investigated. In this work, a real textile wastewater from an exhaustion dyebath has been treated, which contains the following reactive dyes: Procion Yellow H-E4R (CI Reactive Yellow 84), Procion Blue H-ERD (CI Reactive Blue 160) and Procion Red H-E3B (CI Reactive Red 120), in addition to auxiliary compounds normally found in dyeing processes with reactive dyes. The dyes Remazol Blue RR and Remazol Turquoise Blue G (Reactive Blue 21) have also been examined in view of the presence of heavy metals in these molecules. The microemulsion system comprised dodecyl ammonium chloride (as a cationic surfactant), water or wastewater as aqueous phase, kerosene as oil phase, and one of the following alcohols as cosurfactant: isoamyl alcohol, n-butyl alcohol and n-octyl alcohol. The pseudo-ternary diagrams were constructed in order to define Winsor s equilibrium regions. The influence of parameters such as pH, C/S (cosurfactant/surfactant) ratio, distribution coefficient, initial dye concentration, salinity, temperature, phases relative amounts, loading capacity of the microemulsion phase and dye reextraction rate has also been investigated. An experimental planning (Scheff? Net) was used to optimize the extraction process. The removal of color and metals reached levels as high as 99% / A cor do efluente resultante dos processos de tingimento tem sido um dos principais problemas ambientais enfrentados pela ind?stria t?xtil. De modo especial, efluentes contendo corantes reativos s?o altamente resistentes aos processos de tratamento convencionais. Novas tecnologias t?m sido buscadas, algumas j? em escala industrial, por?m nem sempre ? poss?vel atingir a efici?ncia desejada. Por serem utilizadas de forma eficiente em processos de extra??o de metais e de prote?nas, buscou-se utilizar as microemuls?es na extra??o de corantes. Para este estudo, um efluente real foi examinado, consistindo no banho de exaust?o de um processo de tingimento contendo os seguintes corantes: Procion Amarelo H-E4R (CI Reactive Yellow 84), Procion Azul H-ERD (CI Reactive Blue 160) e Procion Vermelho H-E3B (CI Reactive Red 120), al?m de auxiliares normalmente encontrados em processos de tingimento com corantes reativos. Para estudar a remo??o de metais ligados ?s mol?culas dos corantes, utilizaram-se ainda os corantes Remazol Azul RR e Remazol Azul Turquesa G (Reactive Blue 21). Os sistemas de microemuls?o foram formados pelo cloreto de dodecilam?nio (tensoativo cati?nico), ?gua ou efluente como fase aquosa, querosene como fase oleosa e um dos seguintes ?lcoois como cotensoativos: ?lcool isoam?lico, n-butanol e n-octanol. Os diagramas pseudo-tern?rios, representativos dos sistemas microemulsionados em estudo, foram desenvolvidos a fim de delimitar as regi?es de exist?ncia de equil?brio de fases (sistema de classifica??o Winsor). Verificou-se a influ?ncia de par?metros como: pH, raz?o C/T (cotensoativo/tensoativo), coeficiente de distribui??o, concentra??o inicial de corante, salinidade, temperatura, rela??o das fases, capacidade de carga da fase de microemuls?o e reextra??o do corante. Uma metodologia de planejamento experimental (Rede de Scheff?) foi utilizada para otimizar a extra??o. A remo??o da cor e de metais alcan?ou ?ndices de extra??o superiores a 99%
7

Progressive Enlightenment: The Origins of the Gaslight Industry 1780–1820

Tomory, Leslie 28 September 2009 (has links)
Gaslight, an Industrial Revolution technology, developed in the period 1780–1820. The foundations for the technology are partly found in the pneumatic chemistry of the eighteenth century, both in terms of the knowledge of gases and their properties, and the instruments used to manipulate them, such as the gasometer, making gaslight one of the earliest instances of a technology heavily based on science. Although many people experimented with lighting with gases in the late eighteenth century, the move to a commercial technology began with Philippe Lebon and William Murdock who had a clear commercial purpose in mind. The technology in its early phases was found everywhere in Europe, but it was at Boulton & Watt in Birmingham that it was first successfully applied. As Boulton & Watt developed the technology they identified many and solved some of the problems associated with scaling up the technology. They were not, however, very interested in gaslight and only sporadically gave attention to it, before effectively abandoning it around 1812. They nevertheless had an important role to play in its development not only because if their technical work, but also because they demonstrated the technology’s viability to the broad public, and by giving people experience in gas engineering. The technology's final form as a network utility was partly as a result of a battle fought between Boulton & Watt and Frederick Winsor's Gas Light and Coke Company in London during 1807–1810. Boutlon & Watt did not want a large limited-liability corporation as a competitor, and the contest in Parliament between the two groups resulted in a negotiated compromise where the Gas Light and Coke Company gave up all rights to manufacture apparatus, and focused exclusively on gas provision, effectively making it a utility. The years from 1812–1820 saw the technology mature into a large network which included not only technical development, such as the pressure balancing with valves and regulators, but also political and social elements, such as the control of user expectations through education and usage enforcement through inspectors. By 1820, the technology was sufficiently developed to be transferred to the Continent.
8

Progressive Enlightenment: The Origins of the Gaslight Industry 1780–1820

Tomory, Leslie 28 September 2009 (has links)
Gaslight, an Industrial Revolution technology, developed in the period 1780–1820. The foundations for the technology are partly found in the pneumatic chemistry of the eighteenth century, both in terms of the knowledge of gases and their properties, and the instruments used to manipulate them, such as the gasometer, making gaslight one of the earliest instances of a technology heavily based on science. Although many people experimented with lighting with gases in the late eighteenth century, the move to a commercial technology began with Philippe Lebon and William Murdock who had a clear commercial purpose in mind. The technology in its early phases was found everywhere in Europe, but it was at Boulton & Watt in Birmingham that it was first successfully applied. As Boulton & Watt developed the technology they identified many and solved some of the problems associated with scaling up the technology. They were not, however, very interested in gaslight and only sporadically gave attention to it, before effectively abandoning it around 1812. They nevertheless had an important role to play in its development not only because if their technical work, but also because they demonstrated the technology’s viability to the broad public, and by giving people experience in gas engineering. The technology's final form as a network utility was partly as a result of a battle fought between Boulton & Watt and Frederick Winsor's Gas Light and Coke Company in London during 1807–1810. Boutlon & Watt did not want a large limited-liability corporation as a competitor, and the contest in Parliament between the two groups resulted in a negotiated compromise where the Gas Light and Coke Company gave up all rights to manufacture apparatus, and focused exclusively on gas provision, effectively making it a utility. The years from 1812–1820 saw the technology mature into a large network which included not only technical development, such as the pressure balancing with valves and regulators, but also political and social elements, such as the control of user expectations through education and usage enforcement through inspectors. By 1820, the technology was sufficiently developed to be transferred to the Continent.
9

Rêves et cauchemars de la modernité New-Yorkaise : sociologie de l'œuvre en songes de Winsor McCay / Dreams and nightmares of New-York modernity : sociology of Winsor McCay's sleepy stories

Tellez, Benoît 09 December 2015 (has links)
Il y a quelque chose à prendre au sérieux à la lecture des bandes dessinées de Winsor McCay. C’est sur ce postulat, qu’après avoir décidé que mon corpus se limiterait à son œuvre en songes (toutes les planches qui finissent par une case où le personnage se réveille et réalise qu’il vient de rêver), j’ai envisagé de découvrir ce que l’on pouvait apprendre de la modernité new-yorkaise à lecture de Little Nemo in Slumberland (publié de 1905 à 1927) et de Dreams of the Rarebit Fiend (Les cauchemars de l’amateur de fondue au chester, publié de 1904 à1914). Cette thèse débute par une réflexion sur le concept esthétique et philosophique de la Modernité, et l’établissement méthodologique d’une sociologie de l’œuvre ouverte à la singularité de l’auteur. Elle détaille la construction de son matériel d’analyse et les limites qui se sont révélées à l’usage. Mon analyse de l’œuvre en songes de McCay se divise en deux étapes : l’une s’astreint à une étude différenciée de la case, de l’entre-case et de la planche, afin d’organiser le regard ;l’autre retient de l’œuvre quelques grandes trajectoires. Ce dernier développement permet de mettre l’accent sur la passion moderne du mouvement, le devenir de la fin de l’histoire à l’ère du sériel et le recours à la notion d’infini dans le processus de narration. Cette étude est aussi l’occasion de développer des concepts comme la saute, la création machinale, la rationalité baudelairienne ou le récit d’élection. / There is something serious about reading Winsor McCay's comics. It is based on this basic premise that, after I had decided that I would restrict my corpus to his sleepy stories (all the storyboard in which in the last panel the character wakes up and realizes that he wasdreaming), I intend to seek for what could be taught of new yorker modernity through the reading of Little Nemo in Slumberland (published from 1905 to 1929) and of Dreams of the Rarebit Fiend (published from 1904 to 1914). This thesis begins with a thought on a estheticand philosophical concept of Modernity and goes on with a methodic establishment of sociology of the work of art that encompasses the singularity of the author.I divided my analysis of the sleepy stories of McCay in two steps : one whose aims is toorganize the look provides a differentiated study of the panel, the gutters and the page ; the other one focus on main paths of the work. This last development allows to emphasize the modern passion of movement, the outcome of the end of the story in the age of seria lproduction and the concept of infinity in narrative process. This study also gives the opportunity to develop concepts such as tellings of the chosen one, mechanical creation,baudelerian rationality or the concept of skip.
10

Aspects of Performance in Three Works for Piano and Tape: Larry Austin's Sonata Concertante, Thomas Clark's Peninsula, and Phil Winsor's Passages

Brandenburg, Octavia 05 1900 (has links)
This dissertation primarily concerns performance aspects in compositions for piano and tape, using three specific works as the basis for discussion: Larry Austin's Sonata Concertante, Thomas Clark's Peninsula, and Phil Winsor's Passages. These compositions are representative of the medium as a whole, yet each offers its own unique set of performance problems.

Page generated in 0.1052 seconds