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Morris, Dana L. "Effects of forest fragmentation on reproductive effort and productivity of Indigo buntings (Passerina cyanea)." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4118.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 18, 2006) Vita. Includes bibliographical references.
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Inden-Lohmar, Christoph. "Sukzession, Struktur und Dynamik von Libellenpopulationen an Kleingewässern, unter besonderer Berücksichtigung der Ökologie von Aeshna cyanea (Müller, 1764) /." [S.l. : s.n.], 1997. http://www.gbv.de/dms/bs/toc/243389426.pdf.
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Gronell, Ann M. "Sexual dimorphism : its causes and correlates in the orange-tailed blue damselfish, Chrysiptera cyanea (Pisces : Pomacentridae)." Phd thesis, Department of Zoology, 1988. http://hdl.handle.net/2123/12043.
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Belemtougri, Gourounga Raymond. "Détection immunohistochimique de molécules peptidiques et d'amines : leur coexistence dans le système nerveux d'Aeshna cyanea (insecte, odonate)." Lille 1, 1986. http://www.theses.fr/1986LIL10065.
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Belemtougri, Gourounga. "Détection immunohistochimique de molécules peptidiques et d'amines, leur coexistence dans le système nerveux d'Aeshna cyanea, insecte, odonate." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37595822s.
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Boonzaier, Julia. "Morphology and mucin histochemistry of the gastrointestinal tracts of three insectivorous mammals : Acomys spinosissimus, Crocidura cyanea and Amblysomus hottentotus." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20220.
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Thesis (MsCMedSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The gastrointestinal morphology and the distribution of the different types of mucin secreting goblet cells were investigated in three mammalian insectivorous species, namely A. spinosissimus, C. cyanea and A. hottentotus. The aim of the study was to provide a comprehensive morphological comparison between the different species. Another aim was to illustrate and compare the distribution of mucins (neutral, sulfo- and sialomucins) in the gastrointestinal tracts (GITs) of these species, in order to better understand the quality of the biofilm in the GIT. Mucins secreted onto the surface of the GIT have an effect on the colonisation of microflora in the mucosal layer, constructing a biofilm which protects the GIT surface from opportunistic pathogens. The shape, proportional length, and proportional surface areas of the different gastrointestinal regions were recorded and compared in the three species. Histochemical staining methods were used to detect and to distinguish between neutral, sulfo- and sialomucins. The number of goblet cells in the GIT containing each of the above mucins in the epithelium lining the surface or crypts was quantified, and the data expressed as the number of neutral, sulfo- or sialomucin containing goblet cells per mm2 of the surface or crypt epithelium. In all three species the stomach was uncompartmentalised. The internal aspect of the stomach in A. spinosissimus was hemi-glandular, containing stratified squamous epithelium in the fundus, with glandular epithelium in the body and pyloric region. However, C. cyanea and A. hottentotus had wholly glandular stomachs. A. spinosissimus was the only species studied that had a caecum which demonstrated transverse mucosal folds and V-shaped mucosal folds in the proximal colon. Both C. cyanea and A. hottentotus had villi up to the distal part of the GIT. Longitudinal mucosal folds were present in the distal colon. The GITs of both C. cyanea and A. hottentotus showed little morphological differentiation namely a simple, glandular stomach and the lack of a caecum. Mixed (neutral and acid) mucins and mixed acid (sulfo- and sialomucins) mucin secreting goblet cells were prominent mucin cell types in all three mammalian insectivorous species. Despite these general similarities, marked differences were observed in the qualitative expression and distribution of the three types of mucins throughout the GIT. The overall similarity between the three insectivores and other distantly related mammalian species suggests that mixed mucin secreting goblet cell types are prominent contributors to the maintenance of the intestinal biofilm in the majority of mammals, irrespective of their diet or taxonomy.
AFRIKAANSE OPSOMMING: Die bestudering van die morfologie van die spysverteringskanaal (SVK) en die verspreiding van die verskillende musien produserende bekerselle was in drie insek-etende soogdier spesies uitgevoer, naamlik in A. spinosissimus, C. cyanea en A. hottentotus. Die doel van die studie was om „n omvattende morfologiese vergelyking te maak tussen die drie spesies, sowel as om die verspreiding van die verskillende musiene te beskryf in die SVK. Kennis van die verspreiding van die verskillende tipes musiene (neutral, sulfaat en nie-sulfaat bevattende musiene) kan moontlik inligting verskaf aangaande die kwaliteit van die biofilm in the SVK. Die laasgenoemde musiene wat gesekreteer word op die oppervlak van die SVK, bepaal die kolonisasie van die mikroflora in die mukosale laag wat „n biofilm vorm en die SVK beskerm teen patogene. Die vorm, proportionele lengte en proportionele oppervlaks areas van die verskillende SVK gebiede is opgeteken, waarna dit vergelyk is tussen die drie insektivore spesies. Histochemiese kleurings tegnieke is gebruik om die musiene waar te neem en om te onderskei tussen die neutraal, sulfaat en nie-sulfaat bevattende musiene. Die aantal beker selle wat elk van die bogenoemde musiene bevat het, is getel in die oppervlaks epiteel- en kript areas van die SVK. Hierdie data is weergegee as die aantal neutraal, sulfaat en nie-sulfaat bevattende beker selle per oppervlaks epiteel- of kript area (mm2). Die vorm van die maag in al drie spesies was eenvoudig en nie gekompartementaliseer nie. Die interne aspek van die maag in A. spinosissimus het meerlagige plaveisel epiteel in die fundus gehad en klieragtige epiteel in die liggaam en pilorus gedeeltes. Daarbenewens het C. cyanea en A. hottentotus slegs klieragtige epiteel in die maag gehad. A. spinosissimus was die enigste spesie in hierdie studie wat „n sekum gehad het met dwars voue, asook V-vormige mukosale voue in die proksimale kolon. Beide C. cyanea en A. hottentotus het villi tot in die distale gedeelte van die SVK gehad. Longitudinale mukosale voue was teenwoordig in die distale gedeelte van die kolon. Die SVK van beide C. cyanea en A. hottentotus het min morfologiese differensiasie getoon deurdat die spesies „n eenvoudige, klieragtige maag gehad het en geen sekum nie. Gemenge (neutral en suur) musiene asook gemengde suur (sulfaat en nie-sulfaat bevattende) musiene was die dominante musien tipes in the SVK van al drie insek-etende soogdier spesies. Ten spyte van die algemene ooreenkomste, was daar merkwaardige verskille in die getalle en verspreiding van die verskillende musiene in die SVK. Die algemene ooreenkomste tussen die drie insektivore soogdier spesies met soogdiere van ander families, stel voor dat die gemende musien sekreterende beker selle „n prominente bydrae maak tot die onderhoud van die biofilm in the SVK in die meerderheid van soogdiere, ongeag van hul dieet of spesie klassifikasie.
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Ceder, Patric, and Christopher Jönsson. "Tillväxttakt hos sydsvenska populationer av trollsländor (Odonata) i ett varmare klimat - en pilotstudie." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35081.
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In order to gain better understanding of climate change effects on ecosystems, it is necessary to study the response of different species to predicted climate change. Dragonflies are, due to their ecology, a suitable organism group for conducting such studies. In this pilot study we examined the response in growth- and mortality rate to increased ambient temperatures in an experimental set-up of three temperature levels (20°C, 22°C och 24°C) in larvae of three species from the Aeshnidae family (Aeshna grandis, Aeshna cyanea and Anax imperator). A. imperator were, due to insufficient number of collected specimens, excluded in the 22°C temperature regime. The studied species are reproducing in Sweden, but A. grandis and A. cyanea are native, whereas A. imperator is considered newly established since it was first discovered in Sweden in the early 2000’s. Our results show that A. grandis and A. cyanea reacted positively to an increased ambient temperature, in terms of growth rates. However, the response to increased temperatures differed between the two species as A. grandis showed both higher growth- and mortality rate, compared to A. cyanea. Thus, we assume that both species are likely to benefit from the ongoing climate change, but that interactions between them may change. Further studies are required to elucidate how the two species will be affected in presence of newly established species, such as A. imperator. Although, based on our results, the competitiveness of both native species might increase with rising temperatures - which should be considered in future conservation planning.
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Guard, Martin. "Assessment of the artisanal fishery for Octopus cyanea Gray 1849 in Tanzania : catch dynamics, fisheries biology, socio-economics and implications for management." Thesis, University of Aberdeen, 2003. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=232573.
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Catch dynamics, fisheries biology and socio-economic dependence are described for the artisanal fishery for Octopus cyanea at three study sites (Kwale. Jibondo, and Mtwara) along the coat of Tanzania. A total of 23,165 octopuses were measured and sexed from 3,514 individual catches. FIShing effort was shown to be 2.9 times greater at Msangamkuu compared to Jibondo and nearly two times more than Kwale. Number of relaxation days between fishing events, when the octopus stock are able to recover through growth and immigration, was shown to be greater at Iibondo than for the other two sites. Marked reductions in catch landings, mean individual weight, catch per unit effort (kg) and size distributions are reported for Msangamkuu and Kwale when compared to Jibondo. Abundance of octopus was however, higher at the former sites most likely in response to predator and competition release. Stock size and biomass (kg) were calculated for Msangamkuu using a De-Lury depletion method and results extrapolated to the other two sites. Despite higher abundance at Msangamkuu and Kwale mean overall biomass (kg) was 36% and 14% respectively lower tban the mean biomass estimate for Jibondo. Spatial comparison of fishing impacts between sites using a surplus production model suggested Jibondo to be more productive and fishing pressure sustainable. In contrast, Msangamkuu was indicated to be seriously overtished and Kwale somewhere in between. Although, Bhattacharya modal progression analyses separated multiple size modes in monthly samples growth analyses were unsuccessful due to the lack of a clear corresponding pattern of modal progression in monthly size distributions. Length weight relationships varied between sites and sexes. All length weight relationships were negative allometric. Size reductions at Kwale and Msangambru may be impacting on reproductive output with a 40% reduction in the number of mature males at Msangamkuu and 24% reduction at Kwale when compared to Jibondo. Fewer mature females were observed at Msangamkuu and Kwale but even at Jibondo mature females accounted for only 2.2% of the catch. Results suggest spawning activity takes place in deeper water ( > 4m) below the fisbed zone. Nonetheless, enough females would have to reach brooding size at each site to contribute to the reproductive stock. Size at first maturity for females was estimated to be 1800g. Only 3.9% of the octopus at Kwale and 1.2% at Msangamkuu weigh more than 1800g compared to 17% at Jibondo. Fecundity was shown to increase with size. Breeding activity is likely to be year round but maturity peaks were evident for June and July and October to November. The den enrichment experiment indicated a clear preference for concrete dens over PVC pipe. Overall density increased by 10% subsequent to den placement but dens were shown in reef areas not to be limiting. The benefit of den enrichment was therefore ambiguous but could be initiated using a phased approach to gauge effectiveness. The artisanal octopus fisheries make an important contnbution to the local economy. population growth and fisher and trader immigrations were noted as the greatest threats to the octopus fishery by fishers. Awareness of relevant marine resource use issues was shown to be high yet enthusiasm for management varied between sites. The first descriptive details of the octopus fauna of Tanzania are provided. Implications for management of the octopus fishery and a series of proposed management actions are provided for discussion between relevant stakeholders.
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Caron, Laurent. "Epuration en cuivre de bains de décapage sulfurique : mise au point d'un procédé couplant extraction liquide - liquide et dépôt électrochimique." Châtenay-Malabry, Ecole centrale de Paris, 1999. http://www.theses.fr/1999ECAP0620.
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L'étirage à froid de tubes en acier nécessite une préparation de leur surface. Celle-ci implique l'élimination de la couche d'oxydes superficiels ou décapage. Les tubes sont alors plongés dans un bain d'acide sulfurique à 70°C. Impureté de l'acier, le cuivre est mis en solution lors du décapage puis recouvre la surface du tube au-delà d'une certaine concentration ce qui gêne les opérations ultérieures. Par cette étude, nous nous proposons de mettre au point un procédé d'élimination du cuivre du bain de décapage basé sur le couplage de l'extraction liquide-liquide et du dépôt électrochimique. Les contraintes sont : le cuivre est peu concentré alors que l'acide sulfurique et le fer le son et le traitement du bain doit s'effectuer à 70°C. Nous avons donc déterminé la composition du solvant d'extraction qui garantit la sélectivité d'extraction du cuivre II vis-à-vis des cations du fer, une grande vitesse de transfert et la meilleure résistance à la dégradation. Notre choix s'est porté sur une solution comprenant un acide thiophosphinique et une salicylaldoxime dans le dodécane. Le cuivre est ensuite transféré dans une solution aqueuse de thiourée et d'acide sulfurique qui répond aux exigences antagonistes de désextraire le cuivre du solvant de manière efficace tout en permettant le dépôt électrochimique. Enfin, en modifiant légèrement la composition du bain de décapage, nous avons pu minimiser la dégradation du solvant. Un essai sur micropilote nous a permis d'estimer la consommation d'acide thiophosphinique. La faisabilité des opérations en continu a été vérifiée et nous avons pu déterminer des coefficients apparents de transfert qui nous ont permis d'estimer les dimensions d'une unité de taille industrielle.
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Kihlbom, Caroline. "Separation of Cobalt and Nickel using CYANEX 272 for Solvent Extraction." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293919.
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This project aimed to examine the separation of cobalt and nickel using solvent extraction (SX) with the extractant CYANEX 272 (C272). It was intended to investigate the Co-Ni separation in a sulphate-based leach solution in presence of other contaminants. This is an area of interest because of the difficulty of separating metals of similar properties within the field of hydrometallurgy. Batch tests, with varying modifiers and diluents, were carried out to examine the effect of organic phase composition on phase separation. The effect of pH on equilibrium was investigated by constructing equilibrium curves. Through various shaking tests, different separation parameters were studied. McCabe-Thiele diagrams were constructed to predict design parameters. In order to simulate a continuous 3-stage countercurrent solvent extraction, batch tests were performed. Scrubbing, as means of impurity removal was also investigated. Finally, the product’s purity was examined by the help of crystallization. The organic feed mixture that resulted in a sufficient phase separation consisted of C272, tributyl phosphate and naphtha. At pH 4, equilibrium curves showed that equilibrium was either not reached or affected by competing metal ions. A standard equilibrium curve appearance was seen at pH 4.5, resulting in that the theoretical required stages for extraction was calculated to 3 stages (A/O=1). However, a McCabe-Thiele diagram did not give an accurate representation of the more complex case (presence of contaminants). Batch simulation results gave a cobalt recovery of 69% and 100% at pH 4.5 and 4.8, and a nickel recovery of 0% and 3%, respectively. A recommended pH-value for solvent extraction could not be stated, because the choice must be based on operation specifications. Therefore, several different aspects (Co recovery, purity, and economical etc.), must be accounted for. A similar pH-trend was shown in scrubbing, where an increase of pH resulted in an increase of metal ions’ organic concentration. For stripping, acid test results proved 24 g/L sulphuric acid to give the highest cobalt concentration, with a marginal difference in concentration of impurities. An overview of the entire SX process, indicated that extraction, scrubbing, and stripping were all successful operations. The extraction stage showed a Co and Ni recovery of 99% and 0.02%, respectively, and a separation factor of 14250. Distribution results indicated that Al was difficult to remove and was transferred with Co into the product. Therefore, this element must be removed before SX. From noticing an increase of Co:Ni ratio throughout the process, solvent extraction was considered an effective separation method for cobalt and nickel separation. A considerably high purity of cobalt sulphate was produced. However, impurities Al and Ca were also detected in the product. Increasing the acetone volume in crystallization resulted in an increase of Co purity. An increase of the cobalt sulphate crystals formed was observed when increasing the acetone volume, where no impurities were detected.
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Lanagan, Matthew D. "The solvent extraction behaviour of chromium with Bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex [R] 272)." Thesis, Curtin University, 2003. http://hdl.handle.net/20.500.11937/528.
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The bulk of the world's known nickel reserves are contained in laterite ores but sulphidic ores remain the main source of the Western world's nickel production. With the continuing increase in nickel consumption and the depletion of sulphidic ores, the traditional source of nickel, the extraction of nickel from lateritic ores has been the subject of research interest worldwide. Advances in pressure acid leaching (PAL) technology have resulted in significant commercial attempts to extract nickel from these ores. Leaching the ore with sulphuric acid at elevated temperatures and pressures allows almost complete dissolution of the nickel and cobalt, a valuable byproduct of these ores, but yields highly contaminated pregnant leach solutions. Separating and purifying the nickel and cobalt from these solutions remains a hindrance to full commercial production. Several purifying techniques have been commercialised but all suffer from continuing technical problems. Among them, however, the direct solvent extraction (DSX) technique offers several advantages. Direct solvent extraction involves the separation of the nickel and cobalt directly from the partially neutralised pregnant liquor stream (PLS) by solvent extraction with Cyanex(R) 272 as the extractant. However certain contaminants adversely affect the solvent extraction process. Among them is chromium and little is known about the solvent extraction behaviour of this metal. The present work investigated the solvent extraction of chromium with Cyanex(R) 272. It was found that the solvent extraction behaviour of chromium(III) and chromium(VI), both of which could be found in PAL-generated PLS, are distinctly different.For chromium(III), solvent extraction tests showed that (a) it is extracted in the pH range 4-7; (b) the extraction is partly influenced by diffusion; (c) the apparent equilibration time is significantly longer than most transition metals; (d) increases in temperature from 22 to 40 C resulted in increases in the extraction; (e) the pH0.5 increases in the order nitrate < chloride < sulphate in the presence of these anions; (f) the presence of acetate depresses extraction of chromium(III) when the solution is allowed to stand before extraction; (g) in the PLS, chromium(III) precipitated at lower pH than that predicted by the solubility product principle; and (h) the pH0.5 decreases as the Cyanex(R) 272 concentration increases. Chromium(III) is initially extracted by solvation of its inner sphere complex, which then undergoes further reaction in the organic phase leading to the formation of a much more stable species that is difficult to strip. A reaction scheme together with a description of both the initially extracted and resulting stable species is proposed. Extraction of chromium(VI), on the other hand, (a) occurs at pH less than 2 by solvation of chromic acid; (b) is independent of the aqueous phase composition; (c) does not occur in the pH range (3-6) used in the separation of nickel and cobalt. The latter is irrespective of temperature up to 40 C, the use of industrial PLS as the aqueous phase or the presence of an anti-oxidant in the organic phase. The stripping of chromium(III) from a loaded organic phase can be achieved using 1-4 mol L-1 mineral acids provided the stable organic species have not formed making industrial scale stripping of chromium(III) from Cyanex(R) 272 difficult. The exact composition of the aqueous phase during extraction affects the stripping efficiency.
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El-Ammouri, Elias G. "Hafnium solvent extraction from chloride solutions using organophosphorus reagents (Cyanex 923, 925)." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69792.
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A comparison of hafnium solvent extraction from hydrochloric acid solutions using either Cyanex 923 or 925 (organic extractants) diluted in kerosene was established. Since understanding of the hafnium-hydrochloric acid solution is important, development of a speciation diagram for such a solution was carried out. While both Cyanex 923 and 925 are mixtures of trialkyl phosphine oxides, the trialkyl group in the former have straight chains, while those in the latter have branched chains.Experimentally, the major variables studied were hydrochloric acid, hafnium and Cyanex concentrations. Hafnium is rapidly loaded as the tetrachloride complex by a solvation reaction forming a disolvate with the extractant (923 or 925). While extraction increases with increasing acid concentration, it decreases with increasing hafnium concentration due to polymerization. Total chloride level is the controlling factor provided there is enough acid to prevent hafnium hydrolysis and polymerization. Cyanex 923 is a more powerful extractant than Cyanex 925 for given conditions. A few experiments have shown that a very dilute hydrochloric acid solution is suitable as a stripping agent.
The main objective is to evaluate the potential of Cyanex 923 (or 925) as an alternative to MIBK due to the problems associated with the latter. MIBK is the conventional extractant for hafnium and zirconium extraction and separation from hydrochloric acid/thiocyanate solutions. Thus, preliminary studies of hafnium and zirconium (existing separately or together) extraction from hydrochloric acid/thiocyanate solutions were also performed. When existing separately, hafnium and zirconium are similarly extracted into either Cyanex reagents, but when both metals coexist in the same solution, preferential separation of hafnium is observed.
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Souza, Ariane Gaspari Oliveira. "Recuperação de óxido de escândio de alta pureza de resíduos industriais da cadeia de produção do níquel." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-22082016-110903/.
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O Escândio é um elemento terra rara, utilizado principalmente em ligas de alumínio, células combustíveis de óxido sólido e na produção de lâmpadas de haletos metálicos. Apesar de ser o 31° elemento mais abundante na crosta terrestre, raramente é encontrado concentrado na crosta terrestre, e sua produção é sempre associada ao processamento de outros minerais na forma de um subproduto, ou a recuperação de sucata. Minérios de Níquel podem conter teores de Sc variando de 50 a 350ppm e resíduos gerados durante seu processamento pode concentrar o Sc acima de 1000ppm. A recuperação do Escândio de um resíduo da cadeia de produção do Níquel foi estudada, de modo a obter um óxido com pureza acima de 99,0% para aplicações industriais. O resíduo utilizado é um precipitado, na forma de hidróxido, e contém principalmente Fe, Cu, Ni e Co, sendo o teor de Escândio em base seca aproximadamente 1000ppm. O processo de recuperação proposto consiste na lixiviação atmosférica do resíduo, precipitação seletiva para concentração do escândio e extração por solventes. A lixiviação atmosférica em meio sulfúrico 2,0mol.L-1 a 70°C permitiu a recuperação de 92,5% do Escândio contido no resíduo. Entretanto, não foi seletiva, lixiviando também parte dos demais metais presentes. Após a lixiviação para concentrar o Escândio, antes da extração por solventes, foi realizada uma precipitação com NaOH. O intuito foi precipitar o Fe, principal contaminante presente no lixiviado, entretanto ocorreu a co-precipitação de 95,5% do Sc junto a 65,6% Fe em pH 2,0. O precipitado representou uma concentração do Escândio do resíduo em 5,6 vezes. Esse concentrado de Escândio obtido foi dissolvido em solução de H2SO4 para recuperação do Escândio por extração por solventes. O extrante escolhido foi o Cyanex 923, uma mistura de óxidos alquil-fósfinicos. O mecanismo de extração do Sc pelo Cyanex 923 observado foi a solvatação e a estequiometria da reação 1:2. Foi observado um aumento na extração do Sc com o aumento da concentração de H+. O processo de extração do Sc com o Cyanex 923 é exotérmico, sendo favorecido a temperatura ambiente. O teor de Fe na solução aquosa antes da extração é 35 vezes maior que o Escândio, e apesar do Cyanex 923 ser mais seletivo para o Sc do que para o Fe, parte do Fe é co-extraído. O Fe co-extraído foi removido da fase orgânica por meio de uma lavagem com H2SO4 3mol.L-1 com uma perda de Sc de 1,3%. A reextração do Sc na fase orgânica não foi efetiva utilizando ácidos fortes devido a formação de um complexo estável. Foi utilizado ácido oxálico, técnica consolidada para reextração de terras raras, para recuperação do Sc da solução orgânica e a recuperação do Sc foi de 84,3% para uma solução com 4,0% de ácido oxálico. O oxalato de Sc precipitado foi recuperado por filtração e calcinado a 600°C. O óxido obtido apresentou pureza mínima de 99,0%.Scandium is a rare earth element, used mainly in special aluminum alloys, SOFC\'s and metal halide lamps production. Despite of being the 31st element more abundant in Earth\'s Crust, it is rarely found concentrated in ores, and its production is always related to other minerals processing as a by-product or scrap recovering. Scandium content in Nickel ore may vary between 50 and 350ppm and residues produced during its processing can concentrate Sc above 1000ppm. Scandium recovery from a residue of Nickel processing was studied in order to obtain an oxide with purity higher than 99,0% for industrial applications. The residue used is a hydroxide precipitate, which contains mainly Fe, Cu, Ni and Co, Sc content is around 1000ppm (dry basis). The recovery process proposed consists in atmospheric leaching of the residue, selective precipitation to concentrate the Scandium and solvent extraction. The atmospheric leaching in sulfuric acid 2,0mol.L-1 at 70°C allowed the recovery of 92,5% of the Scandium present in the residue. However it was not selective and part of the other metals present in the residue were also leached. After leaching, in order to concentrate the Sc before solvent extraction, a precipitation with NaOH was performed. The initial aim was to precipitate the Iron - main contaminant present in the leach liquor - nevertheless it occurred the co-precipitation of 95,5% of the Sc besides 65,6% of Fe in pH 2,0. The precipitantion represented a concentration of the Sc in the residue of 5,6 times. The Scandium concentrate obtained was dissolved in a sulfuric acid solution to Sc recovery by solvent extraction. The extractant selected was Cyanex 923, a mixture of alkyl-phosphinic oxides. The mechanism of extraction of Scandium observed was solvation and reaction stechiometry was 1:2. It was observed an increase in Sc extraction rates by increasing the concentration of H+. The extraction of Scandium with Cyanex 923 is exothermic, and favorable at room temperature. The Iron content in aqueous solution before extraction is 35 times higher than that of Scandium, and even though Cyanex 923 being more selective for Sc than Fe, part of the Fe is co-extracted. The Fe co-extracted was removed of the organic phase by H2SO4 3mol.L-1 scrubbing with a Sc loss of 1,3%. The stripping of Scandium from organic phase was not accomplished by using strong acids due to formation of a stable complex. Afterwards, it was used oxalic acid - a technique consolidated for rare earths stripping - and the Sc recovery of organic phase was 84,3% with a solution of 4,0% oxalic acid. The Scandium oxalate precipitated was recovered by filtration and calcinated at 600°C. The Scandium oxide obtained presented 99,0% minimum purity.
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Ebel, Mathias. "Cyanid-Phytoremediation mit Eichhornia crassipes eine alternative Methode zur Aufbereitung cyanid- und kupferhaltiger Abwässer aus dem Goldbergbau /." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=983420270.
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Ehsan, Rashidian. "Biosystematics of the Streptomyces cyaneus species-group." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364845.
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Lanagan, Matthew D. "The solvent extraction behaviour of chromium with Bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex [R] 272)." Curtin University of Technology, Western Australian School of Mines, 2003. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12947.
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The bulk of the world's known nickel reserves are contained in laterite ores but sulphidic ores remain the main source of the Western world's nickel production. With the continuing increase in nickel consumption and the depletion of sulphidic ores, the traditional source of nickel, the extraction of nickel from lateritic ores has been the subject of research interest worldwide. Advances in pressure acid leaching (PAL) technology have resulted in significant commercial attempts to extract nickel from these ores. Leaching the ore with sulphuric acid at elevated temperatures and pressures allows almost complete dissolution of the nickel and cobalt, a valuable byproduct of these ores, but yields highly contaminated pregnant leach solutions. Separating and purifying the nickel and cobalt from these solutions remains a hindrance to full commercial production. Several purifying techniques have been commercialised but all suffer from continuing technical problems. Among them, however, the direct solvent extraction (DSX) technique offers several advantages. Direct solvent extraction involves the separation of the nickel and cobalt directly from the partially neutralised pregnant liquor stream (PLS) by solvent extraction with Cyanex(R) 272 as the extractant. However certain contaminants adversely affect the solvent extraction process. Among them is chromium and little is known about the solvent extraction behaviour of this metal. The present work investigated the solvent extraction of chromium with Cyanex(R) 272. It was found that the solvent extraction behaviour of chromium(III) and chromium(VI), both of which could be found in PAL-generated PLS, are distinctly different.For chromium(III), solvent extraction tests showed that (a) it is extracted in the pH range 4-7; (b) the extraction is partly influenced by diffusion; (c) the apparent equilibration time is significantly longer than most transition metals; (d) increases in temperature from 22 to 40 C resulted in increases in the extraction; (e) the pH0.5 increases in the order nitrate < chloride < sulphate in the presence of these anions; (f) the presence of acetate depresses extraction of chromium(III) when the solution is allowed to stand before extraction; (g) in the PLS, chromium(III) precipitated at lower pH than that predicted by the solubility product principle; and (h) the pH0.5 decreases as the Cyanex(R) 272 concentration increases. Chromium(III) is initially extracted by solvation of its inner sphere complex, which then undergoes further reaction in the organic phase leading to the formation of a much more stable species that is difficult to strip. A reaction scheme together with a description of both the initially extracted and resulting stable species is proposed. Extraction of chromium(VI), on the other hand, (a) occurs at pH less than 2 by solvation of chromic acid; (b) is independent of the aqueous phase composition; (c) does not occur in the pH range (3-6) used in the separation of nickel and cobalt. The latter is irrespective of temperature up to 40 C, the use of industrial PLS as the aqueous phase or the presence of an anti-oxidant in the organic phase. The stripping of chromium(III) from a loaded organic phase can be achieved using 1-4 mol L-1 mineral acids provided the stable organic species have not formed making industrial scale stripping of chromium(III) from Cyanex(R) 272 difficult. The exact composition of the aqueous phase during extraction affects the stripping efficiency.
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Zhao, Ningfeng Eichhorn David M. "Cyano-substituted polypyrazolylborate metal complexes." Diss., Click here for available full-text of this thesis, 2005. http://library.wichita.edu/digitallibrary/etd/2005/d019.pdf.
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Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry."December 2005." Title from PDF title page (viewed on February 8, 2007). Thesis adviser: David Eichhorn. Includes bibliographic references (leaves 123-128).
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Greminger, Wolfgang [Verfasser]. "Hydrochemische Prozesse und Cyanid-Freisetzung in Eisenhüttenaltsanden und Gichtgasschlämmen sowie Cyanid-Abbau in Oberflächengewässern und in einer Pflanzenkläranlage / Wolfgang Greminger." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2016. http://d-nb.info/1225685834/34.
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Lanagan, Matthew Derek. "The solvent extraction behaviour of chromium with Bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex(R) 272) /." Full text available, 2002. http://adt.curtin.edu.au/theses/available/adt-WCU20030703.091319.
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Aliprandini, Paula. "O uso da extração por solventes para tratamento de licor de lixiviação de minério limonítico de níquel." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-23022017-110109/.
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O minério limonítico de níquel é considerado uma fonte de níquel e cobalto a partir de mineração. No entanto, o minério é heterogêneo e a concentração dos metais varia conforme a localização. Sendo assim, é necessário o desenvolvimento de uma metodologia que permita determinar os parâmetros de operação de um processo de separação de metais levando em consideração a composição de cada minério. No processo hidrometalúrgico, diversas técnicas de purificação ou separação dos metais podem ser usadas. O presente trabalho estudou o uso da extração por solventes para tratar o licor baseado no lixiviado de minério limonítico de níquel. No processo de extração por solventes foram determinados os parâmetros de extração dos metais como: pH, concentração do extratante na fase orgânica e diluído em querosene, relação entre as fases aquosa e orgânica (A/O) e número de contatos contracorrente teóricos para extração do metal. A extração de 100% do ferro utilizando Cyanex 272 foi determinada em pH 2, concentração do extratante 25% em volume diluído em querosene, relação A/O 1/3 e três contatos contracorrente. Durante a extração do ferro também houve coextração de 27% do cobalto. Foi possível recuperar o cobre da solução através da extração utilizando Acorga M5640 em pH 2, concentração do extratante na fase orgânica igual 5% v/v, relação entre as fases 1/1 e um contato contracorrente. O alumínio e o zinco foram extraídos em pH 3,5, utilizado Cyanex 272 como extratante na concentração 25% em volume, relação A/O 1/2 e dois contatos contracorrente. A fim de obter uma solução aquosa contendo apenas níquel em solução, a última etapa foi a remoção dos metais remanescentes na solução (cobalto, cromo, magnésio e manganês) utilizando Cyanex 272. O pH para essa extração foi 5, a concentração do extratante 20% v/v, relação entre as fases 1/1 e cinco contatos contracorrente. Ao final, foi possível obter uma solução aquosa contendo níquel em solução na concentração 2,52g/L, o que corresponde a 100% do níquel presente na solução sintética. Além do níquel, 0,19 g/L de magnésio e 0,008g/L de cromo permaneceram na solução final.Nickel limonite ore is a source of nickel and cobalt. However, the ore is heterogeneous and concentration changes according the location of the ore. Therefore, determination of the operating parameters is required to separate the metals taking into account the composition of these ores. Hydrometallurgical process is used to treat leach liquor from ores. This work studied the treatment of synthetic solution based on leach liquor of nickel limonite ore by solvent extraction. During the study was determinated the metals extraction parameters as pH, extractant concentration in the organic phase, aqueous and organic ratio (A/O) and number of theoretical extraction stages. The extraction of iron was 100% using Cyanex 272 at pH 2, extractant concentration 25% (v/v) and three extraction stages at an A/O ratio 1/3. Nevertheless, during the extraction of iron, cobalt was co-extracted. The cobalt lost was 27% at the parameters used to extract. It was possible to recover copper from the synthetic solution using Acorga M5640 as extractant at pH 2, extractant concentration 5% v/v, one extraction stage and an A/O ratio 1/1. Aluminium and zinc were removed from synthetic solution at pH 3.5, organic phase with 25% v/v of Cyanex 272 and two extraction stages at an A/O ratio 1/2. The last part of work was removed cobalt, chromium, magnesium and manganese from the aqueous solution. The reason is staying just nickel in the final solution. Cyanex 272 at pH 5 and 20% v/v concentration was used and five extraction stages and an A/O ratio 1/1 was necessary to extract the metals. The finally solution was composed by 2.52g/L of nickel, corresponding 100% of nickel from synthetic leach liquor of nickel limonite ore. In addition, 0.19g/L of magnesium and 0.008g/L of chromium staying at solution.
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Macpherson, Brendan P. "Discrete cyano-bridged mixed valence systems /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17778.pdf.
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Zhu, Jia Liang. "Reductive alkylation of Ã-cyano ketones." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq39611.pdf.
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Giovanacci, Peter Andrew. "Photodissociation of cyano and nitroso compounds." Thesis, Heriot-Watt University, 1989. http://hdl.handle.net/10399/930.
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Madders, Michael. "The efforts of forestry on hen harriers Circus cyaneus." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362944.
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Kumwimba, Ghislain Mutamba. "Effect of process variables on the kinetic and thermodynamic parameters of platinum solvent extraction by cyanex 921." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/870.
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Thesis(MTech( Engineering))--Cape Peninsula University of Technology, 2012Platinum is a precious metal which may be processed under acidic conditions. Accordingly, the extraction of platinum from an acidic chloride media is of immense practical importance. In this study, the extraction of platinum was investigated in a Pt(IV)-HCl-Cyanex 921 matrix in order to establish the effect of temperature, extractant concentration, pH and the initial platinum concentration which had been used in the evaluated solvent extraction (SX) process. The extractant phase contained a mixture of Cyanex 921 and kerosene. In addition, the extraction mechanism of platinum, and the extracted species, are also described in the study, including the determination of the following: extraction ratio, extractant loading, distribution ratio, thermodynamic parameters, and the kinetic mechanism involved in the Pt(IV)-HCl-Cyanex 921 system used. Inductively coupled plasma emission spectroscopy (ICP-ES) was used to measure the platinum concentration in the aqueous phase with a mass balance being used to determine the concentration of platinum in the organic phase. Using a combination of the variables under investigation, the experiments which were evaluated indicated that it is possible to extract sufficient platinum chlorocomplex under the following conditions: pH of 1, Cyanex 921 concentration of 8% (v/v), temperature of 298 K and an initial platinum concentration of 55.22 mg/L. Under these conditions the maximum organic-phase loading of 253.9 mg/L was achieved as compared to the theoretical loading of 507.24 mg/L. The equilibrium loading of ~50% of the platinum chlorocomplex in the organic phase was achieved after 2400 seconds of reactor operation. In this case, a distribution ratio of 9.4 was achieved. This value was observed to be higher as compared to the other SX conditions evaluated in this study.
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Souza, Marcel Felipe Alves de. "Extração por solventes sinérgica aplicada à separação níquel/cálcio utilizando-se os extratantes Cyanex 272 e D2HEPA." Universidade Federal de Minas Gerais, 2015. http://hdl.handle.net/1843/BUBD-9WUH4D.
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The present work examined the synergistic extraction solvent applied to the separation of calcium and nickel present in synthetic aqueous sulfuric solutions using the commercial organophosphorus extractants D2EHPA (di-2-ethylhexyl phosphoric acid) and Cyanex 272 (bis-2,4,4 -trimethylpentyl phosphinic acid), diluted in n-heptane. The objective was to evaluate the effects of competition between metals in the aqueous phase and between the extractants in the organic phase, both individually and simultaneously. To this end, extractions were analyzed using combinations of mono and bicomponents aqueous phases (only calcium or nickel, and both metals together), and mono and bicomponents organic phases (D2EHPA or Cyanex 272 alone, and both extractants together). Extraction tests were performed at a temperature of (25±2)°C and the volume ratio of phases of unity (A/O = 1), varying the pH from 3.5 to 7.0. The operational parameters used in the analysis of the results were the percentage of metals extraction and calcium/nickel selectivity. Samples of the organic phase were analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) and Raman spectroscopy, in order to infer on the structures of the organometallic species formed during extraction. With regard to competition in the aqueous phase, it was observed that the presence of nickel, at equimolar concentrations of calcium does not interfere with calcium extraction independently of the extractor system used (Cyanex 272, D2EHPA, or D2EHPA + Cyanex 272). The nickel extraction in the presence of calcium is shifted to higher pH values using D2EHPA, as well as with the mixture of extractants. With Cyanex 272, the nickel extraction in the presence of calcium also was changed, but in a small proportion. With respect to competition in the organic phase, it was observed that the extraction curves of metals using the mixture of extractants are similar to those obtained when using only D2EHPA, indicating that it is the main reagent for the extraction of metals by mixing Cyanex 272 + D2EHPA. However, the presence of Cyanex 272 in the bicomponent organic phase favors nickel extraction compared to extraction by D2EHPA, in the presence of calcium, from pH 5, even if the metal extraction by Cyanex 272 separately is not significant in the range of pH evaluated. The mixture Cyanex 272 + D2EHPA is more selective for calcium to nickel (3.5 pH 5.0) compared to extractants separately, reaching a maximum value at pH 4.5. In this pH, the separation factor Ca /Ni with the mixture of extractants is about 17 times higher than with D2EHPA and almost 800 times higher than with Cyanex 272. This result is due to the synergism occurred between extractants, therefore the extractor system proposed is more efficient than the extractants used individually in the evaluated conditions. The FT-IR spectrums of Cyanex 272, D2EHPA and n-heptane obtained corroborated literature, but the analysis of samples loaded organic phase under the conditions studied was inconclusive about the structures formed due to the low concentrations of organic complexes obtained.O presente trabalho avaliou a extração por solventes sinérgica aplicada à separação entre cálcio e níquel presente em soluções aquosas sulfúricas sintéticas utilizando-se os extratantes organofosforados comerciais D2EHPA (di-2-etilhexil ácido fosfórico) e Cyanex 272 (bis-2,4,4-trimetilpentil ácido fosfínico), diluídos em n-heptano. O objetivo consistiu em avaliar os efeitos de competição entre os metais na fase aquosa e entre os extratantes na fase orgânica, tanto individual quanto conjuntamente. Para tal, foram analisadas extrações utilizando-se combinações entre fases aquosas mono e bicomponentes (somente cálcio ou níquel, e ambos os metais conjuntamente) e fases orgânicas mono e bicomponentes (somente D2EHPA ou Cyanex 272, e ambos extratantes conjuntamente). Os ensaios de extração foram realizados a temperatura de (25±2)°C e relação volumétrica entre as fases aquosa e orgânica (A/O) unitária, variando-se o pH de 3,5 a 7,0. Os parâmetros operacionais usados na análise dos resultados foram o percentual de extração dos metais e a seletividade cálcio/níquel. Amostras da fase orgânica foram analisadas por Espectrometria de infravermelho por transformada de Fourier (FT-IR) e Espectroscopia Raman, com o intuito de inferir sobre as estruturas organometálicas formadas durante a extração. No que se refere à competição na fase aquosa, tem-se que a presença de níquel, em concentrações equimolares à de cálcio, não interfere na extração de cálcio independentemente do sistema extrator usado (Cyanex 272, D2EHPA ou Cyanex 272 + D2EHPA). Já a extração de níquel na presença de cálcio é deslocada para maiores valores de pH utilizando o D2EHPA e também a mistura de extratantes. Com o Cyanex 272, a extração de níquel na presença de cálcio também sofre alteração, mas em pequena proporção. Com relação à competição na fase orgânica, observou-se que as curvas de extração dos metais utilizando-se a mistura de extratantes são semelhantes àquelas obtidas ao se usar somente D2EHPA, indicando ser esse reagente o principal responsável pela extração dos metais pela mistura Cyanex 272 + D2EHPA. No entanto, a presença de Cyanex 272 na fase orgânica bicomponente favorece a extração de níquel comparada à extração pelo D2EHPA, em presença de cálcio, a partir de pH 5, mesmo que a extração do metal pelo Cyanex 272 separadamente não seja considerável na faixa de pH avaliada. A mistura Cyanex 272 + D2EHPA é bastante seletiva ao cálcio frente ao níquel (3,5 pH 5,0) comparado aos extratantes separadamente, atingindo valor máximo em pH 4,5. Nesse pH, o fator de separação Ca/Ni com a mistura de extratantes é cerca de 17 vezes maior que com o D2EHPA e quase 800 vezes maior que com o Cyanex 272. Este resultado deve-se ao sinergismo ocorrido entre os extratantes, sendo o sistema extrator proposto superior aos extratantes usados individualmente nas condições avaliadas. O espectro FT-IR do Cyanex 272, D2EHPA e n-heptano puros foram obtidos e concordaram com a literatura, porém as análises das amostras de fase orgânica carregadas com organometálicos nas condições estudadas foram inconclusivas sobre as estruturas formadas em decorrência das baixas concentrações de organocomplexos obtidas.
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Rafiq, Shagufta. "Microbial transformations of nitro- and cyano-arenes." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/11292.
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Ouillon, Isabelle. "Copolymérisation de monomères captodatifs avec des dérives cyanés : caracterisations et propriétés." Saint-Etienne, 1997. http://www.theses.fr/1997STET4010.
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Depuis la découverte du caractère piézoélectrique du copolymère alterne et amorphe préparé à partir du cyanure de vinylidene et de l'acétate de vinyle, de nombreux copolymères similaires ont été synthétisés. Nous avons effectué la copolymérisation de dérives cyanés avec des monomères captodatifs. Ils possèdent sur le même carbone un groupe donneur et accepteur d'électrons. Les synthèses de deux monomères captodatifs ont été effectuées : le méthyl - - acétoxyacrylate (maa) et le méthyl - 4 - méthoxycarbonylvinycarbonate (mmc) ainsi que la synthèse d'un dérive cyané le cyanure de vinylidene (vcn). Les autres monomères commerciaux utilises sont l'acrylonitrile, le méthacrylonitrile et le cyanovinylacétate. Diverses copolymérisations en masse sont effectuées à partir d'un dérivé cyane et un monomère captodatif. Sur chaque nouveau copolymère, différentes caractérisations physiques ont été effectuées, telles que la mesure de la température de transition vitreuse, la détermination des masses moléculaires et pour certains d'entre eux une mesure de la viscosité. La microstructure de ces polymères a été étudiée par rmn #1#3c pour déterminer la répartition des stéréoséquences. La détermination des taux de réactivite suivant les méthodes Fineman-Ross et Kelen-Tudos permet de confirmer les hypothèses émises lors de l'étude rmn #1#3c. L'étude thermique de certains copolymères a mis en évidence les mécanismes de décomposition en température, leur stabilité thermique et certains paramètres cinétiques tels que les constantes de vitesse, les énergies d'activation. Le modèle d'élimination aléatoire et autocatalytique a été validé pour l'un des polymères. Des mesures diélectriques ont été effectuées, elles ont permis de mettre en évidence un phénomène de relaxation aux abords de tg. La valeur de l'incrément diélectrique est faible pour tous les composés étudiés.
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Hort, Mariana Appel. "Estudo das atividades vasodilatadora e antioxidante de Cyathea phalerata Mart (Cyatheaceae)." Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/88723.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em FarmacologiaMade available in DSpace on 2012-10-22T12:49:31Z (GMT). No. of bitstreams: 1 230241.pdf: 975395 bytes, checksum: e71c6d82630aa4dba1e9f2852b78bd59 (MD5)
O estresse oxidativo desempenha um importante papel na patogênese de várias doenças humanas, tais como injúria por isquemia e reperfusão, aterosclerose, doenças neurodegenerativas e câncer. No sistema cardiovascular, os radicais livres estão envolvidos principalmente no desenvolvimento da hipertensão e aterosclerose. Neste contexto, o presente trabalho teve como objetivo investigar, in vitro e in vivo, a atividade antioxidante de Cyathea phalerata, além de sua atividade vasodilatadora em anéis de aorta torácica isolada de rato. A atividade antioxidante in vitro foi avaliada através da medida da capacidade seqüestradora do Extrato Bruto (EB), Precipitado (PPT), Fração Aquosa (FAQ), Fração n-Butanol (FBU) e Fração Acetato de Etila (FAE), sobre os radicais DPPH, O2"- e OH", e sobre a peroxidação lipídica. Nestes ensaios foi possível observar o relevante potencial antioxidante da FAE, principalmente a sua capacidade de captar o radical OH" e inibir a peroxidação lipídica. A avaliação in vivo do estresse oxidativo foi realizada em camundongos pré-tratados com a FAE (10, 30 ou 100 mg/kg) e posteriormente expostos ao tetracloreto de carbono (CCl4), através da medida ex vivo de fragmentação do DNA, carbonilação de proteínas e lipoperoxidação de membranas, e das defesas antioxidantes (concentração de GSH e atividades de CAT e GST). A FAE foi capaz de reduzir o dano induzido pelo agente estressor (CCl4) ao DNA, lipídeos e proteínas e aumentar a atividade das enzimas CAT e GST. O importante potencial antioxidante apresentado pela FAE de Cyathea phalerata levou ao estudo desta fração em um modelo de reatividade vascular in vitro (aorta torácica isolada de ratos). A FAE apresentou um efeito vasodilatador dependente da camada de células endoteliais, principalmente nas menores concentrações. A incubação prévia com L-NOARG e ODQ demonstrou a participação da via NO/GMPc no efeito vasodilatador desta fração. Além disso, prostaciclina produzida pelas células endoteliais também parece participar desta atividade. A FAE não alterou a contração induzida pela fenilefrina e nem o relaxamento induzido pelo SNP. O relevante potencial antioxidante e a atividade vasodilatadora de Cyathea phalerata podem estar relacionados à sua composição química, rica em flavonóides. Esta planta pode ser importante para o tratamento de patologias que envolvem estresse oxidativo, podendo diminuir os dano causados à macromoléculas (lipídeos, proteínas e DNA) e aumentar as defesas antioxidantes. Destaca-se a importância da FAE de Cyathea phalerata, rica em flavonóides, para a prevenção e tratamento de doenças cardiovasculares.
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McClurg, Ryan W. "Synthesis of 2-amino-3-cyano-4H-chromenes." CardinalScholar 1.0, 2010. http://liblink.bsu.edu/uhtbin/catkey/1569021.
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The Knoevenagel reaction is defined by the condensation of an aldehyde or ketone with a carbon nucleophile produced by the deprotonation of a methylene species whose acidity is dramatically increased by bonds to strongly electron withdrawing groups. Previously, our group developed an effective one-pot method for the preparation of 4H-chromenes using sodium borohydride reduction of the cyclized intermediates formed by the Knoevenagel condensation of malononitrile with salicylaldehydes in aqueous ethanol. In this study we outline the extension of these strategies to include 2’-hydoxyphenylketones as the starting material. Many of these compounds are also unique and were prepared by Friedel-Crafts acylation of phenols with acyl chlorides and/or Fries Rearrangement of the corresponding phenyl ester. The objective of this project has been to expand the application of the methods optimized in our lab for the simple and efficient formation of carbon-carbon bonds via the selective reduction of the alkylidene portion of the Knoevenagel reaction products. These methods have allowed for the production of several important classes of natural product-like compounds. Specifically, in this investigation, we have adapted these methods to the production of various 4-alkyl and 4-aryl substituted 3-amino-2-cyano-4H-chromenes. These types of molecules exhibit diverse pharmacological activity and have been shown to be potentially useful for the treatment of various diseases. A subset of the synthesized compounds will be submitted to Eli Lilly through their PD2 program. Further variation of substrates included the reaction of salicylaldehydes with ethyl cyanoacetate or cyanoacetamide which provided products unreported in the literature. Reactions with cyanoacetates gave the expected 3-carboethoxy(ester) functionalized 4H-chromene compounds. Products from cyanoacetamide were found to occur in open rather than cyclized forms.Introduction and background literature -- Synthesis of 2'-hydroxyphenylketones -- Synthesis of 2-amino-3-cyano-4H-chromenes -- One pot method applied to salicylaldehydes with ethylcyanoacetate or cyanoacetamide.
Department of Chemistry
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Al-Jebouri, Hamza Yaseen. "Synthesis of butadiene sulphone derivatives with cyano substituents." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/847181/.
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The vicinal dicyano compounds are good starting materials for the synthesis of macromolecules such as phthalocyanines and tetrazaporphins. The synthesis of cyano compounds and vicinal dicyano compounds, particularly the cyano derivatives of butadiene sulphones have been studied in this work. This thesis is divided into five chapters as follows: The first chapter contains a general introduction about organic cyanides; their preparations, reactions and applications. In the second chapter, the synthesis of butadiene sulphone derivatives leading to mono and dicyano substituents is dealt with. It includes some mechanistic studies as well as spectroscopic studies by means of ir, [1]H nmr and mass spectrometry. Chapter three discusses the synthesis of 3-cyano-and 3,4-dicyanodihydrothiophene. Oxidation of dihydrothiophenes into butadiene sulphones is also discussed in this chapter. The synthesis of alpha,beta-unsaturated nitriles from ketones and aldehydes, and in particular, the synthesis of 2,3-dicyano-1,3-butadiene is discussed in chapter four. The addition of hydrogen cyanide to alpha,beta-unsaturated nitriles is also discussed. Chapter five deals with the multistep synthesis of 2,3-dicyano-1,3-butadiene from phthalic anhydride. It also contains some mechanistic studies.
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Raynaud, Michèle. "Application des méthodes de la chimie quantique à l'étude de la réactivité et des propriétés électroniques de composés organiques cyanés." Paris 11, 1989. http://www.theses.fr/1989PA112298.
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Les fonctions d'ondes ab-initio de molécules vinyliques cyanées, comme l'acrylonitrile et l'allyl cyanide, en présence d'un champ électrique intense, ont été calculées dans le but d'étudier les effets in duits par le champ sur les propriétés et la réactivité de ces composés. Un champ très intense doit être imposé pour induire un déplacement électronique significatif par rapport à celui provoqué hors champ par le groupement CN lui-même. On observe un transfert électronique opposé entre élec tron pi et sigma et une augmentation de la polarité de la liaison vinylique. L'évolution sous champ des distributions spatiales des orbitales moléculaires de l'acrylonitrile accroît le recouvrement de la dernière occupée et de la première vide lors de l'interaction de deux monomères. L'allyl cyanide a un comportement différent. Les propriétés électroniques du poly acrylonitrile ont été étudiées par Spectrocopie de Photoemission X. Les structures de cœur et de valence observées sont interprétées grâce au calcul des potentiels d'ionisation de molécules modèles. On observe une levée de dégénérescence des niveaux pi CN et la signature d'effets liés à la tacticité et la conformation du polymère est recherchée par simulation théorique. Enfin, les niveaux vides de films supportés de polyacrylonitrile ont été étudiés par Spectroscopie d'Absorption X près du seuil d'absorption. On observe une levée de dégénérescence ce des niveaux inoccupés pi CN et dans le film de vingt angström d'épaisseur, des effets d'intensité liés à la polarisation de la lumière incidente qui mettent en évidence une orientation perpendiculaire au substrat et aux groupements CN du squelette carboné de polymère.
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Randi, Áurea Maria. "Aspectos fotomorfogênicos, bioquimicos e citoquímicos durante a germinação de cyathea delgadii sternb." Campinas, 1987. http://repositorio.ufsc.br/xmlui/handle/123456789/75382.
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Dissertacão (mestrado) - Universidade Estadual de Campinas. Instituto de Biologia. Programa de Pós-Graduação de Ciências BiologicasMade available in DSpace on 2012-10-16T00:47:40Z (GMT). No. of bitstreams: 0Bitstream added on 2013-07-16T17:09:23Z : No. of bitstreams: 1 264782.pdf: 4740486 bytes, checksum: fdda9cf55fbe989717731fe2b009df86 (MD5)
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McCullagh, John Francis. "Chromatographic studies of nucleophilic substitution in cyano cobalt complexes." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356946.
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Etienne, Michel. "Réactivité de complexes dinucléaires hydrure et alcénylidène ponte du fer vis-a-vis d'hydrocarbures cyanes insatures (mono et dicyanoacétylène, tétracyanoethylène)." Brest, 1988. http://www.theses.fr/1988BRES2009.
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Preparation de complexes avec des coordinats cyano-4 butadienyldene portants. On obtient egalement des complexes dinucleaires avec le tricyano-3,4,4 butadienylidene-1,3. Mecanisme ses reactions de migration de l'hydrogene allylique
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Guimaraes, Alexandre Silva. "Purificação de níquel a partir de soluções sulfúricas por extração por solventes utilizando-se Cyanex 272 e misturas de extratantes." Universidade Federal de Minas Gerais, 2014. http://hdl.handle.net/1843/BUBD-9KGT73.
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The purification of aqueous solutions simulating leach liquors of sulfuric acid lateritic ores containing calcium, cobalt, copper, magnesium, manganese, nickel and zinc employing the solvent extraction technique using the extractant Cyanex 272 and mixtures of Cyanex 272 with versatic acid, Cyanex 301, naphthenic acid, mixture of carboxylic acids (MAC) and D2EHPA, diluted in n-heptane, was investigated in the present work. The main objective was to develop an organic extraction system formed by combining suitable extractants aiming to obtain a liquor purity in conditions such that allow its direct routing to the nickel eletrodeposition step. The solvent extraction tests were carried out at 50°C maintaining the volume ratio of the aqueous and organic phases (A/O) at unit, and varying the conditions of acidity of the liquor in the pH range from 2 to 7 (the pre-treatment step of liquor, when solely Cyanex 272 was used as extractant), and from 3.8 to 7.0 (in the purification step of nickel, when mixtures of extractants were used). The liquor was pre-purified in relation to the metals Co, Cu, Mn and Zn at pH = 3.88 and 20%v/v Cyanex 272, so that remain in the raffinate about 98.5% nickel, 76% calcium and 64% magnesium. Potential extractants systems have been identified: versatic acid (10%v/v), naphthenic acid (10%v/v), MAC (5 and 10%v/v) and D2EHPA (5 and 10%v/v) mixed with Cyanex 272 (20%v/v), which were found to be susceptible to promote the purification of liquor to nickel against alkaline earth metals calcium and magnesium. The combination of 5%v/v D2EHPA with 20%v/v Cyanex 272, at pH 4.8, was identified as the most suitable for the purification of organic liquor extractor system for extracting preferably high levels of calcium (about 72%) and magnesium (about 60%) over nickel (extractions around 2%), thus allowing to obtain a raffinate stream with about 96% nickel that can be routed directly to step eletrodeposition.A purificação de soluções aquosas simulando licores da lixiviação sulfúrica de minérios lateríticos contendo cálcio, cobalto, cobre, magnésio, manganês, níquel e zinco empregando-se a técnica de extração por solventes utilizando-se o extratante Cyanex 272 e misturas de Cyanex 272 com ácido versático, Cyanex 301, ácido naftênico, misturas de ácidos carboxílicos (MAC), e D2EHPA, diluídos em n-heptano, foi investigada no presente trabalho. O objetivo principal consistiu no desenvolvimento de um sistema extrativo orgânico formado pela combinação mais apropriada entre extratantes visando-se obter um licor em condições de pureza tal que permita seu encaminhamento direto à etapa de eletrorrecuperação de níquel. Os ensaios de extração por solventes foram conduzidos a 50°C, mantendo-se a razão entre os volumes das fases aquosa e orgânica (A/O) unitária, e variando-se a condição de acidez do licor na faixa de pH entre 2 e 7 (na etapa de Pré-tratamento do licor, quando se utilizou somente Cyanex 272 como extratante), e entre 3,8 a 7,0 (na etapa de Purificação de níquel, quando se utilizou misturas entre extratantes). O licor foi pré-purificado em relação aos metais Co, Cu, Mn e Zn, em pH = 3,88 e 20%v/v de Cyanex 272, de forma que permanecem no refinado cerca de 98,5% de níquel, 76% de cálcio e 64% de magnésio. Foram identificados os seguintes potenciais sistemas extratores: ácido versático (10%v/v), ácido naftênico (10%v/v), MAC (5 e 10%v/v) e D2EHPA (5 e 10%v/v) misturados com Cyanex 272 (20%v/v), suscetíveis de promover a purificação do licor em relação ao níquel frente aos metais alcalinos terrosos, cálcio e magnésio. A combinação de 5%v/v de D2EHPA com 20%v/v de Cyanex 272, em pH = 4,8, foi identificada como o sistema extrator orgânico mais adequado para purificação do licor, por extrair preferencialmente elevados teores de cálcio (aproximadamente 72%) e magnésio (cerca de 60%), em detrimento do níquel (extrações em torno de 2%), permitindo a obtenção de um refinado com aproximadamente 96% de níquel passível de ser encaminhado diretamente para a etapa de eletrorrecuperação.
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GOMES, DE LIMA LUIS CARLOS. "Reactions d'alcynes cyanes (monocyanoacethylene et dicyanoacethylene), vis-a-vis de complexes organometalliques du fer, du cobalt, du molybdene et du tungstene." Brest, 1986. http://www.theses.fr/1986BRES2009.
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Etude de la reactivite de complexes thiolates du fer et du tungstene (cp(co)::(n) m(sch::(3))) vis a vis du mono et du dicyanoacetylene. Aptitude des complexes de co(i) a intervenir dans la formation de molecules organiques. Nature des liaisons m-pb(m=mo ou w) dans les complexes cp(co)::(3)m-pbr::(3) et (cp(co)::(3)m)::(2) pbr::(2). Donnes de rmn de **(95)mo et **(207)pb
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Bellanger, Solène. "Etude de la biologie d'une messicole en régression : le bleuet (Centaurea cyanus L.)." Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00741148.
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Depuis les années 1950, l'intensification des pratiques agricoles concourt à une augmentation de la pression anthropique entraînant une raréfaction des espèces spécialistes des parcelles cultivées, ce qui contribue à l'érosion de la diversité biologique des agroécosystèmes. Parmi les espèces en déclin, on compte de nombreuses messicoles dont le bleuet (Centaurea cyanus L.), fleur emblématique des moissons. Or, cette espèce peut rendre des services écosystémiques comme hôte de prédateurs de ravageurs des cultures et ressource privilégiée de certains pollinisateurs qui justifieraient son maintien dans les champs. Nous étudions ici des facteurs biologiques qui pourraient potentiellement contribuer à son déclin : distribution spatiale, potentialité de croissance, diversité génétique des populations, survie des semences, système de reproduction. Nous avons montré, par deux campagnes de relevés, que C. cyanus n'est pas une espèce indicatrice de diversité floristique dans la parcelle cultivée. Toutefois, lorsque que le bleuet est rare dans une région, il est associé à d'autres messicoles peu fréquentes. Par contre, s'il est commun, il est associé aux zones ayant la plus forte diversité végétale. Une expérience de semis dans différents compartiments de l'agrosystème, en absence de traitements herbicides, a mis en évidence que la potentialité de croissance des bleuets est plus élevée dans le plein champ du blé que dans la moutarde et les interfaces blé/bordure. Cette croissance est limitée de manière variable par les communautés adventices présentes dans les compartiments hors champs (bordures). L'analyse de la diversité génétique à l'aide de marqueurs microsatellites de bleuets dans une petite zone agricole montre que les populations sont connectées par des flux de gènes importants. Les barrières écologiques telles que les chemins, semblent être des facteurs de structuration plus importants que la distance géographique séparant les populations. La répartition du bleuet dans le paysage agricole n'est donc pas aléatoire et apparaît dépendante de la fréquence de l'espèce dans la région ainsi que des différents éléments du paysage. Les caractéristiques du cycle biologique du bleuet ont été étudiées grâce à des expériences au champ et en serre. Nous avons montré que la longévité des akènes enfouis dans le sol chute rapidement après deux ans. Le cycle saisonnier de la dormance permet deux cohortes de levées (automne et printemps). L'étude du système de reproduction a permis de mettre en évidence que les pollinisateurs sont nécessaires pour la fécondation et que les populations sont majoritairement auto-incompatibles. Il existe cependant des individus pseudo auto-incompatibles mais leur fréquence n'est pas liée à la taille des populations ou à leur niveau d'isolement spatial. Par ailleurs, dès que le coefficient de consanguinité augmente dans les populations, la valeur phénotypique des individus baisse. La dépression de consanguinité s'exprime alors principalement pendant la phase de la germination. L'ensemble de ces caractéristiques biologiques peuvent s'avérer défavorables au bleuet dans les agroécosystèmes simplifiés actuels et ont pu entraîner son déclin dans certaines régions
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Karlsson, Emil. "Examining the competitive abilities of cornflower (Centaurea cyanus) in a growth chamber experiment." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-155573.
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Competition between different species (interspecific competition) is an important factor to consider when estimating population trends, geographic distributions, and management options of species. Many historically common vascular plant species found in agricultural environments have been negatively affected by changes in community composition and in turn, changes in competition pressures. Even so, the relative importance of plant competition in an ecological context is still unclear. In this study I examine the competitive ability of the meadow plant cornflower (Centaurea cyanus L.) when grown together with common oat (Avena sativa) and common poppy (Papaver rhoeas), during a seven-week long growth chamber experiment. Seeds were sown in pots in four different setups; 1) C. cyanus control, 2) C. cyanus + P. rhoeas, 3) C. cyanus + A.sativa, 4) All three species. Six different growth parameters were measured (aboveground dry-weight, belowground dry-weight, root length, leaf area, number of leaves and above/belowground dry-weight ratio). I found that growth rates of C. cyanus were significantly inhibited according to all six growth parameters when C. cyanus competed solely with A. sativa. Competition from P. rhoeas had an insignificant effect on C. cyanus growth in five out of six growth parameters. Finally, I discuss the possibility that historically common meadow plants have declined in abundance in part because of weak competitive abilities, and that rare vascular plant species are negatively affected by growing in proximity with cereal crops.
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FALQUE, VIRGINIE. "Syntheses de 2-cyano-1,2,5,6-tetrahydropyridines substituees et de 4-cyano-1,4,6,7,12,12b-hexahydroindolo2,3-aquinolizines par transfert monoelectronique photocatalytique. Applications a la synthese d'alacaloides indoliques." Paris 6, 1997. http://www.theses.fr/1997PA066325.
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Ce travail a consiste en l'extension d'une nouvelle methode efficace de formation d'-aminonitriles, aux derives n-tryptophyl-#3-piperidiniques, aux indolo2,3-aquinolizidines et aux 1,2,5,6-tetrahydropyridines chirales. Cette methode mise au point au laboratoire, realisee par une photocatalyse par transfert monoelectronique a partir d'une amine tertiaire, conduit a un iminium piege in situ sous forme d'-aminonitrile. Ce derive cyane, ainsi obtenu reagit avec un nucleophile pour conduire a des additions 1,2 ou 1,4. Ainsi, une etude d'obtention de 2-cyano-n-tryptophyl-1,2,5,6-tetrahydropyridines a montre que ces derives etaient obtenus avec de bons rendements, et fonctionnalisables en position 4 par une fonction diester, selon une addition de michael, pour conduire apres cyclisation aux derives tetracycliques correspondants. Une seconde etude d'obtention efficace d'indolo2,3-aquinolizidines cyanes nous a permis d'elaborer des systemes tetracycliques fonctionnalises en position 4 par une fonction diester, representatifs d'alcaloides de type corynanthe. Ces systemes resultant de l'addition de l'anion du malonate de dimethyle sur l'iminium conjugue, preforme a partir de l'-aminonitrile, suivie de l'hydrogenation de l'enamine formee ; sont prepares diastereoselectivement. Une synthese formelle et diastereoselective de l'hirsutine a ete realisee. Une derniere etude de photocyanation d'une 1,2,5,6-tetrahydropyridine chirale, obtenue par reduction du sel de pyridinium de (-)--benzylamine prepare par la methode de zincke, a permis la preparation d'-aminonitrile correspondant. Une approche de la 20-epiuleine impliquant une condensation de l'indole en de l'atome d'azote piperidinique a ete envisagee. Cette etape n'a pas conduit de facon satisfaisante au produit de condensation attendu. Ces travaux ont montre l'efficacite de cette photocyanation et son application dans l'approche de composes naturels tels que les alcaloides indoliques.
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Szafranowska, Barbara [Verfasser]. "Coordination Complexes and Networks with Cyano-Substituted Azolates / Barbara Szafranowska." Bonn : Universitäts- und Landesbibliothek Bonn, 2015. http://d-nb.info/1079273271/34.
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Magnier, Dominique. "Structure et thermodynamique de cristaux mixtes de cyano et chloroadamantane." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37599329s.
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Randi, Aurea Maria. "Aspectos fotomorfogenicos, bioquimicos e citoquimicos durante a germinação de esporos de cyatha delgadii Sternb." [s.n.], 1987. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315052.
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Orientador : Gil Martins FelippeTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-07-16T23:16:42Z (GMT). No. of bitstreams: 1 Randi_AureaMaria_D.pdf: 10867051 bytes, checksum: 82addb5c87143254204dfb5c093700f1 (MD5) Previous issue date: 1987
Resumo: As pteridófitas representam um grupo que produz esporos potencialmente úteis para análises fisiológicas e bioquímicas da germinação. No Brasil, há poucos estudos sobre a germinação de esporos de samanbaias. Decidiu-se então realizar estudos dos aspectos da fotomorfogênese de esporos de Cyathea delgadii, cuja germinação dependente de luz. Estudou-se também aspectos da mobilização e síntese de metabólicos durante a germinação. Paralelamente, foram feitos estudos citoquímicos. A germinação foi realizada em meio de cultura líquida, em câmara de crescimento, com temperatura e luz controladas. Foi verificada a germinação sob luz branca constante para esporos coletados em diferentes épocas do ano. Efeito de tratamento luminosos curtos únicos ou intermitentes e de tratamentos luminosos longos foi verificado em esporos secos e em esporos pré-emvebidos em vapor de água, utilizando-se diferentes fontes luminosas. Foi obsevada a reversão do efeito da luz vermelha pelo vermelho extremo. Efeito de luz azul foi estudado. Esporos foram pré-embebidos em solução osmótica de polietilenoglicol e seu efeito na geminação sob luz branca foi estudado. Efeito de DCMU também foi estudado. Verificou-se o efeito de temperaturas constantes e temperaturas alternadas para esporos que receberam tratamento luminosos indutores de curta duração. Extrações e dosagens de lipídios, clorofila, proteínas, açucares solúveis totais, açucares redutores e amido foram realizadas para esporos secos e após 7 e 11 dias de embebição para germinação, sob luz branca contínua a '25GRAUS¿C. ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Not informed.
Doutorado
Biologia Vegetal
Doutor em Ciências Biológicas
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Villarreal, y. López Eva Gloria. "NMR-spektroskopische Untersuchungen an Peptiden und Proteinen Untersuchungen zu Omphalotin und unter Verwendung des Programms CYANA zur IIB-Domäne des Mannosetransporters /." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972265880.
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Urban, Victoria. "Synthesen und Strukturuntersuchungen von Cyano- und Thiocyanato-halogeno-d10-metallaten(I)." [S.l. : s.n.], 2000. http://www.diss.fu-berlin.de/2001/26/index.html.
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Jalilehvand, Farideh. "Structure of hydrated ions and cyano complexes by X-absorption spectroscopy." Doctoral thesis, KTH, Chemistry, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2963.
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Tominaga, Taiga. "Structural studies on cyano group biosynthesis by [NiFe] hydrogenase maturation proteins." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180637.
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Hergué, Noémie. "Nouveaux polymères conjugués dérivés de 4-cyano-3alcoxythiophènes et de dialcoxythiénothiophènes." Angers, 2007. http://www.theses.fr/2007ANGE0049.
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Ce travail porte sur la synthèse de nouveeux polymères utilisant des motifs alcoxythiophènes. Après un rappel sur les propriétés des systèmes conjugués linèaires, la première partie est consacrée à la présentation de nombreux polyalcoxythiophènes décrit dans la littérature. Elle met l'accent sur les effets éléctroniques et structurant des groupements alcoxy sur les propriétés des système conjugués. La seconde partie décrit la synthèse d'un nouveau système donneur/accepteur et la préparation des polymères associés. L'introduction des deux groupements donneur ( alcoxy) et accepteur (nitrile)d'électron sur le même motif thiophène est utilisée pour améliorer l'homogénéité de la densité éléctronique et ainsi préparer des polymères à faible gap. La dernière partie est consacrée à la synthèse de 3,6-dialcoxythiéno[3,2-b]thiophènes et de 3,4-dialcoxythiéno[3,2-b]thiophènes, qui associent la structure intrinsèquement rigide des thiénothiophènes à une autorigidification due à la présence des groupements alcoxy. Les deux types de structures étudiées conduisent à des systèmes présentant des propriétés très différentes et permettent ainsi de moduler les prpriétés électroniques des systèmes conjuguésThis work deals with the synthesis of new polymers using alkoxythiophene derivatives. After a rapid review on the linear conjugated systems properties, a first part is devoted to the presentation of several polyalkoxythiophenes reported in literature. The electronic and structuring effects of the alkoxy groups on the properties og conjugated systems are demonstrated. The second part describes the synthesis of new donner/acceptor systems and the preparation of the resulting polymers. The introduction of electron releasing (alkoxy) and the electron withdrawing (nitrile) groups on the same thiophene ring is used to increase the electronic density homogeneity and to prepare low bandgap polymers. The last part is devoted to the synthesis of 3,6-dialkoxythiéno[3,2-b]thiophene and de 3,4-dialkoxythiéno[3,2-b]thiophene, wich associate the intrinsically rigid structure of thienothiophenes and the autorigidification due to the presence of alkoxy groups. The two structure leads to systems presenting very different properties, thus allowing the modulation of the electronic properties of the various conjugatede systems
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Claytor, Robinson C. P. "Structure and microwave spectrum of the 2-cyano-2-propyl radical." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53935.
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The rotational spectra of the 2-cyano-2-propyl and d⁶-2·cyano-2-propyl radicals were observed using a Stark modulated spectrometer. The radicals were generated in the gas phase by UV irradiation of sublimed azoisobisbutyronitrile. They were detectable in the cell for approximately one hour. Thirty-three transitions were assigned for (CH₃)₂CCN and twenty-one for (CD₃)₂CCN. The rigid rotor rotational constants determined by calculation of the hypothetical unsplit rotational transitions are A=8276.7, B=3919.7, C=2751.5Mhz for (CH₃)₂CCN and A=6241.3, B=3490.7, C=2372.6Mhz for (CD₃)₂CCN.
A program to calculate the fine splittings and hyperfine splittings due to the ¹⁴N nucleus and six protons was written. The spin rotation constants determined for the two species were Eaa=-69.9, Ebb=-36.1, Ecc=2.7Mhz and Eaa=-55.4, Ebb=-32.6 Mhz for (CH₃)₂CCN and (CD₃)₂CCN respectively. The hyperfine coupling constants for ¹⁴N are identical for both isotopic species and were found to be Taa=-17.2, Tbb=-17.1 and Tcc=34.4 Mhz. The proton and deuteron hyperfine splittings were not resolved. The structural parameters determined from an Ph. D.
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Molina, Calderón Lorena Paola. "Transferencia de lantano (III), cerio (III), praseodimio (III) y neodimio (III) a través de membranas líquidas emulsificadas utilizando cyanex 272 como agente transportador." Tesis, Universidad de Chile, 2012. http://www.repositorio.uchile.cl/handle/2250/111235.
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Memoria para optar al título de QuímicoEn esta Memoria de Titulo se estudió la transferencia del lantano (III), cerio (III), praseodimio (III) y neodimio (III), desde una fase acuosa de alimentación hacia una fase acuosa de retroextracción, por medio del transportador órgano fosforado CYANEX 272 contenido en una membrana liquida emulsificada. En primera instancia se estudió el comportamiento ácido base de cuatro extractantes (D2EHPA, PC-88A, CYANEX 272, CYANEX 301) permitiendo conocer sus pKa aparentes y su disponibilidad para reaccionar con los iones Tierras Raras (TR) a ciertos pH. A partir de este conocimiento y las reacciones de extracción propiamente tales fue posible proponer la utilización de una fase acuosa de alimentación tamponada con el ácido 3-cloropropiónico a pH 4. A través de los experimentos de extracción por solvente de cada uno de los iones TR con los cuatro extractantes en estudio, se determinó que el extractante más adecuado para el proceso fue el CYANEX 272, debido a su alta capacidad de extracción y mayor selectividad con los cuatro iones TR. Si bien en un principio todos los experimentos se realizaron con alimentaciones monometálicas, después fue preciso probar el grado de competencia que se generaría al realizar la extracción de los iones lantánidos desde una alimentación polimetálica. Los resultados fueron coincidentes con los experimentos de extracción individuales de los iones TR, en donde el lantano es el ión que menos se extrajo en comparación con los otro tres. Por otro lado, los experimentos de retroextracción revelaron que ion cerio presentaba el menor grado de transferencia hacia la fase acuosa interna. Todos estos conocimientos generados revelaron que la dupla Nd-Pr era difícil de separar con las condiciones ya establecidas. Por esta razón se agregó EDTA como agente quelante a una alimentación que contenía estos dos iones en iguales concentraciones (2mM), lográndose un coeficiente de selectividad máximo (SPr/Nd) de 1,7. Los experimentos de extracción por solvente (SX) generaron el conocimiento base para los experimentos de transporte de los cuatro iones lantánidos con CYANEX 272 a través de las Membranas Líquidas Emulsificadas (MLE). Previo al inicio de los experimentos de transferencia fue necesario lograr una doble emulsión de estabilidad adecuada en función de las concentraciones variables de sus componentes: transportador CYANEX 272, tensoactivo SPAN 80, Ln+3 (lantánidos) total y HCl en la fase acuosa de retroextracción. A partir del estudio de estabilidad, se observó que la concentración del tensoactivo SPAN 80 presentó el efecto más crítico, donde una cantidad insuficiente produjo pérdida de la fase acuosa interna, disminuyendo el rendimiento de extracción. Por otro lado, una cantidad excesiva de SPAN 80 provocó el hinchamiento de la emulsión primaria. Como consecuencia de esto la fase acuosa interna que contiene al ion de interés se diluye o pierde pureza. En términos generales, para conservar el volumen de 75 mL de emulsión primaria, formada por 25 mL de fase acuosa interna más 50 mL de fase orgánica, es necesario utilizar alrededor de 1,2% p/v de SPAN 80, cuando la concentración en la alimentación de cada uno de los ETR es 0,5 mM. Para concentraciones mayores se necesita aproximadamente entre 2-2,1% p/v de tensoactivo. Con los experimentos preliminares de transferencia de los iones TR en estudio, se pudo determinar que los elementos lantano, cerio, praseodimio y neodimio fueron extraídos eficientemente en el orden del 90% desde la alimentación, mientras que fueron transportados a través de la membrana hacia la fase acuosa interna en un rango entre 40-60%. Posteriormente, un estudio cinético de la extracción de cada uno de los ETR, permitió observar que durante los primeros 5 min los iones cerio, praseodimio y neodimio experimentaron un rápido decaimiento en su concentración en la fase acuosa externa, mientras que para el ion lantano se requirió al menos de 10 min. Finalmente, para lograr un enriquecimiento de cada uno de los iones metálicos mediante MLE desde una solución polimetálica, se realizaron dos diseños experimentales, uno de tipo screening y otro de optimización. Los resultados del primer diseño indicaron que el factor tiempo fue el único que presentó un efecto significativo sobre los porcentajes de extracción y transferencia de los ETR a través de la doble emulsión. En el segundo diseño los resultados indicaron que la presencia de EDTA en la fase acuosa externa tuvo un efecto negativo sobre el grado de transferencia de los iones TR hacia la fase orgánica.
In this work the transference of lanthanum (III), cerium (III), praseodymium (III) and neodymium (III) were studied, from a feed aqueous phase toward a backextraction aqueous phase by means of the organophosphorous CYANEX 272 carrier contained into an emulsified liquid membrane. In the first instance the acid-base behavior of the four extractants (D2EHPA, PC-88A, CYANEX 272 and CYANEX 301) were studied allowing to know their apparent pKa and through it the availability to react with the rare earth ions (RE) at certain pH. From this knowledge and the actual such extraction reactions it was possible to propose the use of a buffered feed aqueous phase with 3-cloropropionic acid at pH 4. Through the solvent extraction experiments for each one of the RE with the considered four extractants, it was determined that the most appropriated extractant for the process was CYANEX 272, owing to its high extraction capacity and better selectivity for the four RE ions. Although at first all experiments were performed with monometallic feeds, afterward it was necessary to test the degree of competition that would be generated to perform the extraction of lanthanide ions from a polymetallic feed solution. The results were consistent with the individual extraction experiments of the RE ions, wherein lanthanum is the lesser extracted ion compared with the other three ones. On the other hand, the backextraction experiments showed that the cerium ion had the lowest degree of transference toward the internal aqueous phase. All this generated knowledge revealed that the pair Nd-Pr was difficult to separate at the established conditions. For this reason, EDTA as a chelating agent was added to the feed solution that contained these two ions at identical concentrations (2 mM), achieving a maximum selectivity coefficient (SPr/Nd) of 1.7. The solvent extraction (SX) experiments generated the base knowledge for the transport experiments of the four lanthanide ions with CYANEX 272 through Emulsified Liquid Membranes (ELM). Before starting the transfer experiments it was necessary to achieve a satisfactory stability of the double emulsion as a function of the variation of the component concentrations: carrier CYANEX 272, surfactant SPAN 80, total Ln3+ (lanthanides) and HCl in the backextraction aqueous phase. From this stability study it was observed that the concentration of SPAN 80 surfactant showed the most significant effect, where an insufficient amount caused the loss of the internal aqueous phase, decreasing the efficiency of extraction. On the other side, an excessive amount of SPAN 80 caused a swelling degree of the primary emulsion. As a consequence the internal aqueous phase that contains the ion of interest is diluted or lost its purity. In general terms, for keeping the volume of 75 mL of the primary emulsion, consisting of 25 mL of internal aqueous solution plus 50 mL of the organic solution, it is necessary to use about 1.2% w/v of the SPAN 80, when the concentration of each the REE in the feeding is 0.5 mM. For higher concentrations of the total REE about 2 to 2.1% w/v of surfactant are needed, approximately. From the preliminary experiments related with the transfer study of the RE ions, it was determined that the lanthanum, cerium, praseodymium and neodymium elements are removed efficiently in the order of 90% from the feed solution, while they were transported across the membrane toward the internal aqueous phase in the range of 40-60%. Afterward, a kinetic study of the extraction of each one of the REE, allowed to note that during the first 5 min of the carrying out tests the cerium, praseodymium and neodymium ions experimented a fast decline in the concentration in the external aqueous phase, whereas for the ion lanthanum at least 10 min was required. Finally, to achieve an enrichment of each one of the metal ions from a polymetallic solution by means MLE, two experimental designs were conducted, a screening one and another one related with the optimization type. The results of the first design indicated that the time factor was the unique significant effect on the extraction and transfer rates of the REE through the double emulsion. In the second design the results indicated that the presence of EDTA in the external aqueous phase has a negative effect on the transfer degree of the RE ions towards the organic phase.
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