Dissertations / Theses on the topic 'Zinc content'
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Evens, Nicholas Philip. "The regulatory mechanisms controlling zinc content in wheat." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/407446/.
Full textPULS, ROBERT WILLIAM. "ADSORPTION OF HEAVY METALS ON SOIL CLAYS (KAOLINITE, CADMIUM, MONTMORILLONITE, ZINC)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183889.
Full textNeilsen, Denise. "Characterization and plant availability of zinc in British Columbia orchard soils." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72835.
Full textMarsh, Sally. "Impact of traffic pollution on the nitrogen metabolism and zinc content of roadside vegetation." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1445685/.
Full textHenshel, Judy 1958. "Copper, manganese, and zinc in Puerco River sediments." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276725.
Full textWijesundara, Chandra. "Response of corn to high levels of CuSO₄ and ZnSO₄ applications." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45959.
Full textMaster of Science
Pietrzak, Kornel. "Fabrication and studies of porous coatings containing calcium, magnesium and zinc on a titanium substrate for mechanical engineering applications : PhD thesis summary : [synopsis]." Rozprawa doktorska, [s.n.], 2021. http://dlibra.tu.koszalin.pl/Content/1316.
Full textRamesh, Sunita. "Molecular mechanism of zinc uptake and regulation in cereals." Title page, table of contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phr1724.pdf.
Full textMfeka, Nonkululeko. "Morphology and mineral content of cowpea lines in response to planting date and zinc application rate." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2672.
Full textCowpea (Vigna unguiculata (L.) Walp) is an important grain and fodder legume grown around the world. It is a dual purpose grain legume crop, providing food for man and livestock. Cowpea is identified as a potential crop to diversify food production, minimize production input by improving soil fertility and improve micronutrients of seed, therefore, improving human nutrition. There is limited information available on cowpea production and suitable agronomic practices including planting date to best suit different environmental conditions in South Africa. The objective of this study was therefore to i) evaluate two soil types (sandy and clay soil) and its effect on cowpea, yield components and mineral composition, ii) the effect of different planting date and iii) assess the effect of zinc fertilizer application rate on vegetative, reproductive parameters and mineral content of cowpea seed. A field trial was conducted in Agricultural Research Council (ARC), in two locations Nietvoorbij (clay loam soil) and Bien Donne’ (sandy soil) during the 2015 summer planting season. The trial layout was conducted in a randomised complete block design (RCBD) with five replicates. The factors of the study include three cowpea lines: Cowpea Veg1, M217 and Qukawa with zinc application rate of (0, 15 and 30 kg/ha) through soil application and two planting date (2 October and 2 November 2015). The following agronomic variables were collected, in both locations: germination rate, number of leaves, number of branches, plant height, number of seed per pod, number of pods per plant, pod length, pods per treatment, pod weight, 100 seed weight, morphological traits, moisture content and seed mineral content. Vegetative data was collected on a fourth-night basis on six middle plants per treatment and reproductive parameters were taken after harvest. The variables were subjected to ANOVA using software SAS (2012). Treatments were tested at 5% level of significance and differences between treatments were separated using LSD and DMRT of the SAS 2012 test. The results indicated that vegetative and reproductive parameters measured varied significantly among cowpea lines in each location and across locations due to different cowpea lines and soil type. Line Cowpea Veg1 and Qukawa were the best performing line in both vegetative and yield parameters across the two planting dates in 2015. These lines significantly obtained higher plant height than line M217. Yield and yield parameters were significantly affected by cowpea line. Qukawa obtained the highest seed yield at Bien Donne’ with a mean of 1184.2 kg/ha and seed yield of 686.25 kg/ha for Cowpea Veg1 at Nietvoorbij. The second planting date (2 November 2015) improved germination of plants across the two locations, therefore improving vegetative growth. Zinc (Zn) fertilizer significantly improved plant height across all treatments. An inconsistent response to yield parameters due to Zn application rate was observed. However, though not significant, Zn application of 15 kg/ha increased most of the measured parameters. It was concluded that line Cowpea Veg1 and Qukawa were the best performing lines. The second planting date (2 November) increase germination rate for both locations. It is therefore, recommended that future research should evaluate Zn fertilizer time of application.
Tadayyon, Ali, Sedigheh Beheshti, and Mohammad Pessarakli. "Effects of sprayed humic acid, iron, and zinc on quantitative and qualitative characteristics of niger plant ( Guizotia abyssinica L.)." Taylor & Francis, 2017. http://hdl.handle.net/10150/626135.
Full textGettier, Stacy W. "Corn response to long-term application of CuSO₄, ZnSO₄ and Cu-enriched pig manure." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49779.
Full textThyrén, Linnea. "Plant-based meat substitutes and their nutritional composition : A study on iron content, zinc content, calcium content and protein quality in meatballs and plant-based substitutes and how they contribute to the goal of reaching recommended daily intakes." Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-96761.
Full textSingbo, Arnaud. "The effect of zinc and soil ph on grain yield and nutrient concentrations in spring wheat cultivated on potted soil." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2845.
Full textZinc deficiency on various soil types have been reported in arable soils of sub Saharan Africa (SSA) including South Africa. A pot trial was conducted at the Cape Peninsula University of Technology, Wellington campus to investigate the interaction of different application rates of Zn at various soil pH on the grain yield and quality of spring wheat in a completely randomized factorial design replicated three times. The four soil pH tested were: pHA: 5.1, pHB: 5.6, pHC: 6.1, pHD: 6.6 which correspond to lime application at 0, 0.5, 1 and 1.5 t/ha. Five Zn rates (Zn1: 3.5; Zn2: 4.5; Zn3: 5.5 Zn4: 6.5, and Zn5: 7.5 mg /kg soil which correspond to Zn1: 7; Zn2: 9; Zn3: 11; Zn4: 13 and Zn5: 15 kg /ha) were applied at two (planting and flowering) growth stages. Yield and yield component data collected were analyzed using SAS version 9.2 and means were separated by Duncun’s Multiple Range Test (DMRT). The results showed that grain yield and yield components were significantly affected by lime application pHC (6.1): 1t/ha at planting. Zn application at planting had no significant effect on the grain yield and yield components. However, at flowering, the simultaneous increase of Zn along with increase in lime positively affected grain yield and yield components. Plant analysis showed that at both stages (planting and flowering), Zn application, especially at pH 6.6, significantly increased P, K, Ca, Na, Mg Fe, Cu and B concentrations in wheat grain, but the concentrations of N, Mn, Zn and protein remained unaffected. Zn application had no effect on most nutrients due to the presence of lime. While the absence of lime, Zn4: 6.5mg/kg (corresponding to 13kg/ha) significantly increased the nutrients. In addition, Zn3: 5.5mg/kg (corresponding to 11kg/ha) promoted Zn absorption by grain in all treatments.
Owojori, Olugbenga J. (Olugbenga John). "Influence of clay content and salinity on the bioavailability and toxicity of metals (copper and zinc) to soil organisms." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1484.
Full textENGLISH ABSTRACT: Metal pollution is a problem of increasing global concern. It could arise from industrial activities, as well as pesticide use in agriculture, among other sources. For adequate protection of the soil ecosystem from metal toxicity, the bioavailability of metals must be properly evaluated. A plethora of soil factors affect the bioavailability of metals to soil organisms. These include pH, clay and organic matter contents, salinity among others. While much is known about the influence of some of these parameters, little is known on how clay content and salinity modify the bioavailability of metals to soil organisms. This study investigated the influence of clay content and salinity on partitioning, uptake and toxicity of two essential metals (Cu and Zn) to the earthworm Eisenia fetida in separate laboratory trials. Partitioning of the metals was evaluated with 0.01 M CaCl2, DTPA (di-ethylene-triamine-penta acetic acid), and nitric acid extractions. The metal content of worms was determined by acid digestion, while growth, cocoon production, and mortality were used as endpoints showing toxicity to metals and/or salinity. To test the validity of some of the laboratory results, a field study was undertaken, using the earthworm Aporrectodea caliginosa. Further, the study assessed the effect of salinity, using a battery of laboratory tests (acute, chronic and avoidance tests) with natural and/or artificial soils on four species of organisms (a collembolan Folsomia candida, a potworm Enchytraeus doerjesi and two earthworm species E. fetida and A. caliginosa), representing different feeding patterns and ecological roles in soil. Results showed that with increased clay content, there was increased availability of Cu in the substrate, and increased toxicity to E. fetida as shown by data for mortality and growth. The situation with Zn was less significant at sub-lethal concentrations but much so at lethal concentrations. DTPA and CaCl2 extracted metals revealed changes in partitioning of Cu and Zn with changes in clay content, but this trend was not always consistent. Both DTPA and CaCl2 revealed increased availability of Zn in substrates with increased salinity. Salinity had an additive to synergistic effect with Zn in toxicity to E. fetida. When combined with Cu, salinity also increased the availability of Cu as shown by CaCl2 extracted fraction, and had additive effect on toxicity of Cu to the earthworm. The field study did not succeed in in iv confirming the results of the laboratory study due to confounding role of flooding after heavy rainfall and subsequent leaching of salts and Cu. The results of the experiment on acute and chronic toxicity tests for NaCl on E. fetida showed LC50 of 5436 mg/kg NaCl and EC50 for growth and cocoon production of 4985 and 2020 mg/kg NaCl. These values showed that earthworms might be negatively affected in many soils containing fairly moderate concentrations of salts. Similarly, A. caliginosa could not survive in natural soil containing relatively low salt concentrations (EC = 1.62 dS/m) while reproduction was severely affected at lower EC value of 0.52 dS/m. F. candida and E. doerjesi could survive in the highest salinity soil (EC = 1.62 dS/m) used in this study but their reproduction was severely affected from 1.03 dS/m. Overall, it appears that of all the taxa used, earthworm species were the most sensitive to saline stress and could proof useful in determining ‘safe levels’ of salt in contaminated soils. The results of the avoidance test showed that A. caliginosa avoided both natural and artificial saline soil containing concentrations lower than those avoided by E. fetida. The conclusion is that the influence of clay content and salinity on the bioavailability of Cu and Zn depends largely on the metal in question, but generally speaking, bioavailability and toxicity of the metals were reduced with increased clay content while the opposite was true for salinity. If the species used in this study can be seen as fairly representative of a wide range of soil organisms, the conclusion is that salinisation of soil will be detrimental to most soil organisms at relatively low saline concentrations. Given the role of beneficial soil organisms in several soil processes which in turn contribute to soil fertility and sustainable use of land, it is recommended that any farming practices that may lead to an increase in salt content of agricultural soils should be discouraged.
AFRIKAANSE OPSOMMING: Metaalbesoedeling is ‘n probleem wat toenemende globale kommer veroorsaak. Dit kan ontstaan as gevolg van industriële aktiwiteite sowel as van plaagmiddelgebruik in die landbou en ander bronne.Ten einde die grondekostelsel genoegsaam te beskerm, moet die biobeskikbaarheid van metale ge-evalueer word. ‘n Verskeidenheid van grondfaktore be-invloed die biobeskikbaarheid van metale vir grondorganismes Hulle sluit onder andere in pH, klei, organiese inhoud en soutgehalte. Hoewel heelwat bekend is oor die rol van sommige van hierdie parameters, is min bekend oor hoe klei en soutgehalte die biobeskikbaarheid van metale vir grondorganismes kan modifieer. Hierdie studie het die invloed van kleiinhoud and soutgehalte op die verdeling/partisie, opname en toksisiteit van twee essensiële metale (Cu en Zn) vir die erdwurm Eisenia fetida in afsonderlike laboratoriumproewe ondersoek. Kompartementele verdeling van die metale is geevalueer deur middel van ekstraksie-metodes met 0.01 M CaCl2, DTPA (di-etileentriamien- penta asysnsuur), en salpertersuur ekstraksies. Die metaalinhoud van wurms is bepaal deur suurverterings en spektrofotometriese analises te doen terwyl groei, kokonproduksie en mortaliteit van organismes gebruik is as gevoeligheidseindpunte om toksisiteit van metale en soutgehalte aan te toon. Om die geldigheid van somige van die laboratoriumresultate te toets, is ‘n veldstudie ook onderneem met die erdwurm Aporrectodea caliginosa. Die effek van soutgehalte is verder ondersoek deur ‘n battery van laboratoriumtoetse met vier spesies (‘n kollembool Folsomia candida,’n potwurm Enchytraeus doerjesi en twee erdwurmspesies E. fetida en A. caliginosa), wat verskillende voedingspatrone verteenwoordig. Die resultate het getoon dat met toenmende klei-inhoud was daar ‘n toename in die beskikbaarheid van Cu vir opname vanuit die substraat, asook ‘n toename in toksisiteit vir E. fetida soos deur die gegewens vir mortaliteit en groei uitgewys. Die situasie met Zn was minder betekenisvol by subletale konsentrasies en selfs baie minder so by letale konsentrasies. DTPA en CaCl2 ge-ekstraheerde metale het veranderinge in die partisie/verdeling van Cu en Zn uitgewys met verandering in klei-inhoud, maar die tendens was nie altyd konstant nie. Beide DTPA en CaCl2 ekstraksie het toenemende beskikbaarheid van Zn in substrate uitgewys met toenemende soutinhoud. Soutinhoud het ‘n additiewe/toegevoegde tot sinergistiese vi toksisiteitseffek saam met Zn vir E. fetida. In kombinasie met Cu het soutgehalte ook die geskatte biobeskikbaarheid van Cu verhoog soos uitgewys deur die CaCl2, geekstraheerde fraksie, en het ‘n additiewe effek gehad op die toksisitiet van Cu vir die erdwurm. Die veldstudie kon nie die resultate van die laboratoriumstudie bevestig nie weens die belemmerende rol van vloede na swaar reënneerslae en daaropvolgende uitloging van soute en Cu. Die resultate van die eksperimentele ondersoek na die akute en chroniese effekte van NaCl op E. fetida het ‘n LC50 van 5436 mg/kg NaCl en EC50 vir groei en kokonproduksie van 4985 en 2020 mg/kg NaCl opgelewer. Hierdie waardes het aangetoon dat erdwurms moontlik negatief beinvloed kan word in baie gronde wat ‘n redelike gemiddelde konsentrasie van soute bevat. Soortgelyk kon A. caliginosa nie oorleef in natuurllike grond wat relatief lae soutkonsentrasies bevat het (EC=1.62 dS/m) nie terwyl voortplanting sterk ge-affekteer is by ‘n lae EC waarde van 0.52 dS/m. F. candida en E. doerjesi kon oorleef in die grond met die hoogste soutgehalte (EC= 1.62 dS/m) maar hulle voortplanting is ernstig geknou vanaf 1.03 dS/m. In geheel blyk dit dat van allle taksa wat gebruik is, erdwurms die sensitiefste was vir die stres wat deur soutgehalte veroorsaak is. Die kennis kan nuttig wees in die bepaling van “veilige vlakke” van sout in gekontamineerde gronde. Die resultate van die vermydingstoetse het getoon dat A. caliginosa beide natuurlike en kunsmatig versoute gronde vermy het by konsentrasies wat heelwat laer was as dié wat deur E. fetida vermy is Die gevolgtrekking is dat die invloed van klei en soutgehalte op die biobeskikbaarheid van Cu en Zn grootliks afhanklik is van die metale wat betrokke is en dat biobeskikbaarheid en toksisiteit normaalweg verminder het met verhoogde klei-inhoud, met die teenoorgestelde wat waar was in die geval van soutgehalte. Indien die spesies wat in die studie gebruik is beskou kan word as redelik verteenwoordigend van ‘n wye reeks van grondorganismes, is die gevolgtrekking dat versouting van gronde nadelig sal wees vir meeste grondorganismes, selfs by relatief lae soutkonsentrasies. In die lig van die rol wat nuttige grondorganismes speel in verskeie grondprosesse wat bydraend is tot grondvrugbaarheid en volhoubare gebruik van gronde, word dit aanbeveel dat enige boerderypraktyk wat mag lei tot verhoging van die soutinhoud van landbougronde ontmoedig moet word.
Bush, Peter G. "Maternal cigarette smoking and placental function : morphology, oxygen diffusive capacity, amino acid and zinc transport, and trace element content." Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU106462.
Full textWheal, Matthew Simon. "The influence of chlorsulfuron on the uptake and utilization of zinc by wheat /." Title page, table of contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phw556.pdf.
Full textSadeghzadeh, Behzad. "Mapping of chromosome regions associated with seed zinc accumulation in barley." University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0204.
Full textAsente, Rebecca Ann. "The effect of non-weight-bearing exercise and protein intake during pregnancy on maternal and fetal zinc content in the Sprague-Dawley rat." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/90906.
Full textM.S.
Achen, Jasinta H. "Evaluation of the nutritional correlates of growth of early and middle stage HIV-infected children in Uganda and zinc content of Ugandan food plants." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83957.
Full textBosshard, Gabriela Zanotto 1986. "Propriedades ópticas e estruturais de óxido de zinco contendo enxofre." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250265.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: O objetivo deste projeto foi investigar a síntese de óxido de zinco contendo enxofre obtido a partir de sulfeto de zinco nas fases wurtzita (hexagonal) e blenda de zinco (cúbica), assim como fazer a caracterização e estudar as alterações estruturais e ópticas dos materiais sintetizados e compará-las às propriedades do óxido de zinco sintetizado a partir de hidroxicarbonato de zinco. O método de síntese utilizado permite a obtenção de sulfeto de zinco hexagonal ou cúbico a baixa temperatura, permitindo um estudo comparativo da influência da estrutura cristalina do sulfeto de zinco na formação do óxido de zinco. Os estudos por difração de raios X mostram que há leve variação nos parâmetros de rede do material obtido, principalmente quando a síntese parte da fase hexagonal do ZnS. Somado a isso, a análise da luminescência dos materiais obtidos mostra emissão em torno de 520 nm, que pode ser atribuída a transição eletrônica entre defeitos de Frenkel (Zni e VZn") que foram formados a temperaturas inferiores à requerida para a formação deste tipo de defeito, indicando, portanto alterações na rede do óxido de zinco contendo enxofre.
Abstract: This project aimed to investigate the synthesis of sulfur-containing zinc oxide obtained from zinc sulfide in the wurtzite (hexagonal) or zinc blende (cubic) phases, in order to study possible changes in the structural and optical properties of the obtained, material which were compared to the properties of zinc oxide synthesized from zinc hydroxicarbonate. The used method of synthesis allowed obtaining zinc sulfide hexagonal or cubic at low temperature and therefore comparative studies of the influence of crystalline structure of zinc sulfide in the formation of zinc oxide was possible. X-ray diffraction data show that there is a slight variation in the lattice parameters of the obtained material, especially in the material synthesized from hexagonal ZnS. In addition to that, luminescence emission around 520 nm, assigned to the electronic transition among Frenkel defects (Zni and VZn"), indicate changes in the network of the sulfur-containing zinc oxide, since this type of defect is expected to be formed at temperatures above the ones used in the present work.
Mestrado
Quimica Inorganica
Mestra em Química
Bueche, Blaine. "The Effect of PEG-Insulin and Insulin Hexamer Assembly on Stability in Solution and Dry Powders. Hexamer Assembly of PEGylated-Insulin and Insulin Studied by Multi-Angle Light Scattering to Rationally Choose the pH and Zinc Content for Analytical Methods and Formulations of Dry Powders." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5688.
Full textFotovat, Amir. "Chemistry of indigenous Zn and Cu in the soil-water system : alkaline sodic and acidic soils." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phf761.pdf.
Full textColán, Victoria Amelia Lázaro. "Perdas em ferritas de manganês zinco: o papel da sinterização e de parâmetros microestruturais." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-30112010-144937/.
Full textThe use of manganese zinc ferrite in power sources of battery chargers is growing, due to its low magnetic power losses at inductions around 0.2 T. These ferrites belong to the soft magnetic materials group, they are polycrystalline ferromagnetic oxides with face centered cubic structure. Powders of this material were compacted in uniaxial press and in automatic press of production, by ring and toroidal form, respectively. Two firing cycles, varying the atmosphere oxygen content between 5 and 15%, were applied to evaluate its effect on microstructure, density, magnetic losses in high induction and permeability. Samples sintered in warmer positions inside the furnace resulted in higher density and larger grain size, as expected, but higher losses at 25 °C were achieved. Increasing the atmosphere oxygen content from 5 to 15% did not alter density significantly, but resulted in a slight increase in grain size. On the other hand, the correlation between oxygen content and losses was complex. There are lower losses, at 60 °C. Similar behavior was observed with hysteresis loss, which is compatible with the change in magnetocrystalline magnetic anisotropy (K1). Measurements were performed from 25 to 100 °C, at 0.2 T, aiming at the evaluation of the effect of temperature on the two parcels of hysteresis loss. Samples sintered at 1290 °C with low atmosphere oxygen content showing a minimum on the losses versus temperature curve. The available techniques to analyze Fe2+ content were not capable of establishing, unequivocally, the expected relation between this variable and the oxygen content of the sintering atmosphere.
Fathi, Shida. "Kontroll av zinkskikt på monterat räckesmaterial." Thesis, KTH, Byggteknik och design, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147182.
Full textControl of zinc coating on assembled railing materials made on site lacks a common methodology. Zinc coating should have a minimum thickness requirements according to the Swedish standard ISO 1461:2009, which is determined by the dimension of the steel thickness. Trafikverket expects that with help from this thesis it could limit the number of measurements on site, otherwise it will take too much time and labor resources, in case control of road and bridge railing systems are required from the customer. Probabilities and sampling in statistics helps us to limit the number of measurements of the protective devices that are made in the field. Using normal distribution, one arrive at the element of method that with reasonable effort gives a fair picture of the layer thickness of the assembled railing materials. Upon variation of the galvanizers on road barrier systems, each part is investigated separately by measuring zinc thickness of a galvanizers, checking the zinc coating thickness on them, take conclusions and later on investigate the next manufacturer. If a crash barrier is less than 30 pieces, the zinc coating thickness is measured at each facility by itself. For calculation of the zinc coating thickness on a mounted railing material one begins with 30 measurements and the use of the central limit theorem to approximate it to normal distribution and analyze the results. The final result of the thesis is an Excel program with input formulas. The Excel program is a tool for producing 95% confidence interval. Using this interval, one can make conclusions that if the zinc coating on a crash barrier fulfills the requirement or not and later on be able to come up with a result. If the requirement is in the interval or larger than the interval, the material is approved.
Allen, Martin Ward. "Schottky Contact Formation to Bulk Zinc Oxide." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/4385.
Full textOliveira, Cristine Santos de 1990. "Sistemas nanoestruturados de ZnO contendo Eu3+ em sílica mesoporosa." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250543.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: O trabalho consistiu na síntese de sistemas nanoestruturados de ZnO contendo Eu em sílica mesoporosa, o vidro poroso Vycor (PVG), utilizando o método de ciclos de impregnação-decomposição (CIDs). Sistemas de nanopartículas puras de ZnO, na forma PVG/10ZnO mostraram que o ZnO apresentou-se predominantemente na forma de sítios de ZnO monodispersos com absorção em 245-250 nm e na forma de nanopartículas, com tamanho médio em torno de 4,5 nm, para as quais inicialmente não se observou uma absorção característica. Através de espectroscopia de luminescência observou-se transferência de energia do ZnO monodisperso para a matriz, porém nenhuma emissão no visível característica de defeitos. Para o sistema PVG/10Eu observou-se transições f-f características nos espectros de emissão e excitação, e a transferência de carga O¿¿Eu. Os sistemas seguintes sintetizados na forma PVG/ZnO@ZnO/M@ZnO, com M = Eu, Al, Sr, Pr e Yb visaram o estudo do sistema principal PVG/ZnO@ZnO/Eu@ZnO, o qual apresentou emissões do Eu relativamente mais intensas do que no sistema PVG/10Eu além de apresentar o favorecimento do crescimento do ZnO sob a forma de nanopartículas, crescendo sobre os aglomerados de dopante. Nessas condições, surge a banda proibida do ZnO em torno de 360 nm, cuja borda é deslocada para menores energias com o número de CIDs, em acordo com uma equação da literatura, indicando um regime de confinamento quântico. Esta banda é observada na luminescência e também transfere energia para a matriz, ainda não sendo observadas emissões de defeitos do ZnO. Estudos com Sr e Al não confirmaram a formação de defeito do tipo Zni decorrente da inserção do íon Eu na rede do óxido. Os espectros de excitação para os sistemas de ZnO contendo Eu não foram conclusivos quanto à transferência de energia devido à presença de bandas do Eu, e num sistema similar substituindo-se por Yb não foi observada esta transferência. Medidas de tempo de vida mostraram um aumento da estabilidade do Eu no sistema com a presença prévia do ZnO, e também sob seu recobrimento. Através das emissões excitônicas do ZnO observou-se o efeito de confinamento quântico também na luminescência, o qual se deu de forma similar ao observado para a análise por absorção no UV-Vis
Abstract: The work consisted in the synthesis of nanostructured systems of ZnO containing Eu loaded in a mesoporous silica, the porous Vycor glass (PVG), using the impregnation-decomposition cycles method (IDCs). Pure ZnO nanoparticles systems synthesized in the form PVG/10ZnO have shown that ZnO presents itself predominantly as monodisperse ZnO sites with absorption at 245-250 nm, and nanoparticles, with mean size around 4,5 nm, for which initially no characteristic absorption had been observed. Through luminescence spectroscopy an energy transfer from monodisperse ZnO to the matrix was observed, but no defect-related emissions. For the PVG/10Eu system Eu characteristic f-f transitions were observed in both emission and excitation spectra, as well as the O¿¿Eu charge transfer. The following systems synthesized in a PVG/ZnO@ZnO/M@ZnO pattern, with M = Eu, Al, Sr, Pr e Yb sought the study of the main system PVG/ZnO@ZnO/Eu@ZnO, which presented Eu emissions relatively more intense than the PVG/10Eu system, also showing favoring growth of ZnO under the form of nanoparticles, which now grow over dopant clusters. Under such condition the ZnO band gap is now observed in UV-Vis absorption analysis, with peaks around 360 nm, whose edge is displaced towards lower energies with increasing number of IDCs, also in agreement with a theoretical equation from the literature, pointing to a condition of quantum confinement. This band is observed in luminescence, and also transfers energy to the matrix, and yet no defect-related emissions are observed for ZnO. Studies with Sr and Al did not confirm the formation of a Zni defect due to the insertion of Eu ions into the oxidefs structure. Excitation spectra for Eu-containing ZnO systems were not conclusive as to the existence of an energy transfer due to the presence of Eu bands in the same range, and in the similar system exchanging Eu3+ for Yb3+ such transfer was not observed. Lifetime measurements have shown an increase in Eu stability within the system with ZnO presence previous to its insertion, or after its coating layer(s). Quantum confinement effect was also observed for the ZnO excitonic emissions in luminescence, showing a similar behavior to that obtained thru UV-Vis absorption analysis
Mestrado
Quimica Inorganica
Mestre em Química
Sellaf, Zenagui. "Élimination par voie électrochimique du zinc contenu dans les effluents industriels." Toulouse, INPT, 1999. http://www.theses.fr/1999INPT028G.
Full textSantos, Marcia Cristina Gonçalves dos. "Avaliação do desempenho de filmes contendo silanos e sais de terras raras para proteção contra corrosão de camadas de ZnFe eletrodepositadas." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263579.
Full textTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Aço galvanizado e aço eletrodepositado com liga ZnFe são materiais comuns na indústria de construção civil e automotiva. Esses materiais à base de zinco necessitam, entretanto, serem protegidos de ambientes corrosivos através de um tratamento de superfície que geralmente contém cromo hexavalente ( Cr6+), tóxico para o meio ambiente e cancerígeno para o homem. O presente trabalho apresenta um estudo com filmes contendo diferentes silanos: viniltrietoxissilano (VS), bis-(1,2-[trietoxissilil] etano) (BTSE) ou bis-(3-[trietoxissilil]-propil? tetrassulfeto (BTESPTS) e nitratos de terras raras (Ce ou La), como revestimentos de conversão para a camada de liga ZnFe. Esses sistemas foram avaliados através das análises de Espectroscopia Fotoelétrica de Emissão de Raios-X (XPS), das Curvas de Polarização, da Espectroscopia de Impedância Eletroquímica (EIE), da Microscopia Eletrônica de Varredura (MEV) e Espectrometria de Energia Dispersiva (EDS). Os resultados de EIE e polarização indicaram que os sistemas estudados foram eficientes contra corrosão e que seu desempenho dependia do tipo de silano. Os sistemas ZnFe+Ce+BTSE+BTESPTS e ZnFe+La+BTSE+BTESPTS mostraram o melhor resultado contra corrosão.
Abstract: Galvanized and zinc electroplated steels are very useful materials in automotive and construction industries. These zinc based materials, however, need to be protected against corrosive environments through a surface treatment that generally has hexavalent chromium wich is toxic to the environment and may cause cancer to human being. This thesis shows a study about films containing different silanes: vinyltriethoxysilane (VS), bis-(1,2-[triethoxysilyl]ethane) (BTSE) or is-(3-[triethoxysilyl]-propyl]tetrasulfide (BTESPTS) and rare earth nitrates (Ce, La) as conversion coatings to the zinc-iron alloy electroplated steel. These systems were evaluated using X-Ray Photoelectron Spectroscopy (XPS), Polarization Curves, Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscopy (SEM) and EDS. The EIS and Polarization results have shown that the systems under study were efficient against corrosion and its performance depended upon the type of silane. The inciron+Ce+BTSE+ BTESPT and zinc-iron+La+BTSE+BTESPT systems have shown the best result against corrosion.
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
Diawara, Jules. "Mouillabilité de surfaces hétérogènes (fer/oxyde) par un alliage de zinc liquide." Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00658768.
Full textGu, Qilin. "Hydrogen peroxide treatment induced rectifying behavior of Au/n-ZnO contact." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/HKUTO/record/B39558344.
Full textSurmann, Luciana Loffredo. "Desenvolvimento de microemuls?es contendo fotoprotetores inorg?nicos nanoparticulador." Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/13437.
Full textCoordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The inorganic actives, represented mainly by microfine zinc oxide and titanium dioxide, have shown great potential to protect against large UV spectrum. The aim of this study is the development, characterization and analysis of stability in the short term of microemulsions containing inorganic fotoprotection agents. The microemulsions identified by the phases diagram containing the metallic oxides were produced by two different methods and subjected to the centrifugation test and thermal stress cycles, and subsequently characterized by macroscopic evaluation, test dilution, electrical conductivity, pH, particle size, and zeta potential. This study highlights the influence of the metal oxides addition in the structure and distribution of micelles in the microemulsions
Os agentes fotoprotetores inorg?nicos, representados principalmente pelo ?xido de zinco e di?xido de tit?nio microfinos, t?m mostrado grande potencial de prote??o contra amplo espectro de radia??o UV. O objetivo deste trabalho consiste no desenvolvimento, caracteriza??o e estudo de estabilidade a curto termo de microemuls?es contendo agentes fotoprotetores inorg?nicos. As microemuls?es identificadas pelo diagrama de fases e adicionadas dos ativos fotoprotetores foram elaboradas a partir de dois m?todos diferentes e submetidas ao teste de centrifuga??o e ciclos gelo-degelo, sendo posteriormente caracterizadas pela avalia??o macrosc?pica, teste de dilui??o, condutividade el?trica, pH, granulometria e determina??o de potencial zeta. Este estudo evidencia a influ?ncia da adi??o dos ?xidos met?licos na estrutura??o micelar e distribui??o de tamanho de part?culas das microemuls?es
Warner, Ronald Douglass. "Zinc and calcium effects on nickel dermatitis in the guinea pig /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487330761217158.
Full textSantos, Marcia Cristina Gonçalves dos. "Estudo de filmes polimericos contendo silanos y-UPS e VS como revestimentos promotores de adesão em superficies galvanizadas e eletrodepositos de ligas ZN/FE e ZN/Co." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263596.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia mecanica
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Resumo: A excelente resistência do Zinco em diferentes ambientes corrosivos e sua habilidade em proteger o aço, fazem do aço galvanizado e eletrodepósitos, materiais comuns na indústria automotiva e de construção civil. Os substratos de aço galvanizado e eletrodepósitos de Zinco necessitam, no entanto, ser protegidos em ambientes altamente corrosivos por revestimentos orgânicos (pinturas).A má aderência do sistema Zinco/pintura faz com que a superfície do substrato de Zinco receba um pré-tratamento contendo Cromo relativamente barato e efetivo porém, tóxico ao homem e ao meio ambiente. Filmes poliméricos contendo silanos organofuncionais surgem como alternativa à substituição de pré-tratamento livre de Cromo hexavalente 'CR POT. +6¿, pois são moléculas que podem atuar como agente de acoplamento, promotores de adesão e como protetoras de superfície. A principal vantagem da sua utilização é a promoção da adesão entre materiais orgânicos (pinturas) e inorgânicos (metais). Os sistemas Galvanizado/Silano e Ligas eletrodepositadas/Silano, foram estudados nesta dissertação. Para tanto, técnicas como EIE (Espectroscopia de Impedância Eletroquímica), XPS (Espectrometria Fotoelétrica de Emissão de Raios-X), Ângulo de Contato e análises microscópicas foram utilizadas. A avaliação da resistência por barreira foi feita através da Espectroscopia de Impedância Eletroquímica em solução de 0,1 M de NaCI, comparando-se os desempenhos dos revestimentos. A cura induziu uma modificação importante nos diagramas de impedância, além de outras variáveis, como a concentração, o tempo de hidrólise, os tipos de silano e os substratos diferentes. Os resultados indicaram o Zn/Co revestido por VS e Zn/Fe revestido por 'gama¿-UPS como os sistemas mais promissores
Abstract: The Zinc' s excellent resistance, as used in differents corrosive environments, and its hability to protect steel, make galvanized steel (HDG) and Zinc electrodepositions very usual materiaIs in the automotive and construction industries. Galvanized steel and Zinc electrodepositions substrates need, however, to be protected from strongly corrosive environments by organic coatings (painting). Zinc/paint system weak adhesion results in a relatively cheap and effective zinc substrate pretreatment, however toxic to humam being, and also to the environment. Organofunctional silanes appear as an altemative to substitute this pretreatment, without making use of hexavalent chromium 'CR POT. +6¿), because they are bifuncional molecules that can act as adhesion promoters and surface protectors. The main benefit to employ them is to promote adhesion between organic (painting) and inorganic (metals) materiaIs. The GalvanizedlSilane and Electrodeposition Alloys/Silane systems had been studied in this essay. Techniques like EIS (Electrochemical Impedance Spectroscopy), XPS (X-Ray Emission Photoeletric Spectrometry), Contact Angle and microscopical analyses were used in this work. The barrier for resistance was evaluated through Electrochemical Impedance Spectroscopy in a 0,1M NaCI solution comparing coatings performances. Curing caused as importante modification in the impedance diagrams, as well as other variables like concentration, hydrolysis time, silane types and different substrates. The results indicate the Zn/Co alloy coated for VS and Zn/Fe alloy coated for 'gama¿-UPS as the systems most promising
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
顧啟琳 and Qilin Gu. "Hydrogen peroxide treatment induced rectifying behavior of Au/n-ZnO contact." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39558344.
Full textAndrade, Jirrah Pedro de. "Desenvolvimento e eficácia clínica de dermocosméticos para a pele acneica contendo vitamina B3 e derivados de vitamina B6 e zinco." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/60/60137/tde-30012014-081127/.
Full textAcne is a skin disease with high prevalence and its treatment is important to prevent permanent skin lesions or the aggravation of psychological disorders due to self-esteem shaken. This way, the development of effective dermocosmetic formulations, that can improve the conditions of this skin type, is very important. Vitamin B3, a vitamin B6 derivative and zinc PCA are among the active ingredients which present potential benefits in the controlling of some pathogenic factors of acne. Thus, the aim of this research was to develop cosmetic formulations for acneic skin containing vitamin B3, vitamin B6 lipophilic derivative and zinc PCA, as well as the evaluation of stability and clinical efficacy. For this purpose, were developed different formulations which, at first, were evaluated in terms of stability face to zinc PCA addition. After this, the others active ingredients were added and the formulations were submitted to preliminary tests of stability and physical stability studies by rheological behavior determination. The most stable formulation was subject to skin compatibility evaluation and vehicle comedogenicity. The formulation with the active ingredients was also evaluated regarding their sensorial characteristics and clinical efficacy. Efficacy studies were performed by means of objective and subjective methods, after a sixweek- period of use of the formulation. The objective methods consisted in non-invasive in vivo methodologies (biophysical techniques and image analysis) where were evaluated hydration, barrier function, lipid content, skin pH and the counting of porphyrins, microcomedones and inflammatories lesions. In relation to subjective methods, was performed the efficacy perception using a questionnaire in order to compare the skin before and after the treatment. The results showed that among the formulations developed, only one kept stable after the stability tests. The formulations were considered as \"very good\" on skin compatibility test and showed no comedogenic potential. In sensorial evaluation, frequencies obtained for the parameters considered bad were low, which indicate the sensorial of the formulation was adequate for the purposes. In clinical efficacy study, the formulation under study did not alter the parameters related to hydration and skin barrier function and was effective in reducing the counting of porphyrins and inflammatories lesions (p<0,05). Clinical evaluation by subjective methods showed the formulation effectiveness regarding the improvement of inflammatory acne, skin oiliness, hydration and softness. Finally, the results obtained showed the formulation developed is effective and compatible with the skin and, besides the importance of research and development for obtaining stable, safe and effective formulations with suitable sensorial.
Meroufel, Abdelkader. "Étude de nouvelles formulations de peintures en poudre riches en zinc et contenant PANI." La Rochelle, 2006. http://www.theses.fr/2006LAROS180.
Full textZinc Rich Primers are widely used in industry to protect the metal structures against corrosive environment. Metal zinc is dispersed in a polymeric matrix in the form of fine dust. These particles must be in electrical contact between them and with the metal substrate, in order to be sacrified and to place the substrate under cathodic protection. However, currently available formulations do not exceed 50 % weight of zinc. This weak zinc rate induces a weak electrical contact in painting and requires the addition of other conducting species for a better cathodic protection. In the continuity of previous works using the carbon black as a conducting pigment, one proposed to study three new formulations containing a conducting polymer as conducting pigment. The results obtained are compared with those of a commercial formulation containing carbon black. The exploration of the mechanisms of protection of its formulations was carried out mainly thanks to the electrochemical spectroscopy of impedance. Microscopic analyses (SEM, EDS) and spectroscopic (Raman) made it possible to bring essential elements in the comprehension of the degradation of various primers in condition of immersion. Finally, an accelerated ageing with the salt sprays and an immersion in the presence of defect were carried out and studied in order to classify the various coatings in terms of protective qualities
Snider, James M. "Zinc pot bearing material wear rate as a function of contact pressure and velocity." Morgantown, W. Va. : [West Virginia University Libraries], 2002. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=2721.
Full textTitle from document title page. Document formatted into pages; contains x, 80 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 69-70).
Tsin, Fabien. "Développement d'un procédé sur grande surface d'électrodépôt d'oxyde de zinc comme contact avant transparent et conducteur de cellules solaires à base de Cu(In,Ga)Se2." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066311/document.
Full textCu(In,Ga)(S,Se)2 (CIGS) thin films based solar cells are a promising technology for high efficiency energy conversion. A window layer completes the stack of the cell. It is commonly constituted by an intrinsic and aluminum doped bi-layer of zinc oxide (ZnO) deposited by magnetron sputtering, an expensive vacuum process. Alternative processes, using low cost and atmospheric techniques, have been developed in order to reduce the costs. The aim of this work was to achieve a functional window layer of ZnO by a photo-assisted electrodeposition process on large scale substrates of CIGS/CdS in aqueous medium and replace the sputtered one. For this purpose, several studies have been carried out in order to determine the optoelectronic properties such as doping level and mobilities of the electrodeposited ZnO and optimize the deposition process. Firstly, the effect of three different electrolytes on the zinc oxide properties and doping has been studied on metallic substrate: chloride medium (Cl-), perchlorate medium (ClO4-) and a mixed medium of perchlorate with boric acid (H3BO3). Then, electrochemical synthesis of zinc oxide as window layer has been performed on CIGS/ CdS substrates. This study allowed to establish the need to synthesize an in situ seed layer which promotes the growth and the compactness of the final layer of zinc oxide. This two-step method has led to the achievement of high photovoltaic performances on large scale with promising efficiencies up to 14.3 % for a solar cell made entirely by atmospheric processes
Buitrago, Leidy Julieth Hernández. "Avaliação microestrutural, cinética e mecânica do comportamento de pelotas auto-redutoras a base de resíduos de aciaria elétrica contendo zinco do processo Waelz." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-17072018-152706/.
Full textSteel production from scrap melting in electric arc furnaces, generates about 10 to 20 kg of waste per metric ton of molten steel, which are composed by fumes and dust containing mainly oxides of iron, zinc, calcium and lead. Thus, these residues are highly dangerous and toxic. To find ecofriendly solutions and mitigate problems of the solid waste, it was proposed to agglomerate electric steel dust (PAE) in the form of self-reducing pellets. The latter are thermally treated by the Waelz process, which consists of a rotary kiln fed by the pellets, recovering the zinc by means of reduction and oxidation metallurgical reactions. In this study, kinetic and mechanical behavior, as well as microstructural changes, were evaluated by fractional factorial design of type 3III experiments (4-2), varying: binder, reducer, temperature and binary basicity. Chemical and microstructural characterization were performed using: Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction XRD, X-ray fluorescence spectrometry (FRX), differential thermal analysis/thermogravimetric (DTA/TG), elemental analysis C-N-H and laser granulometric analysis. The PAE studied presented 37. 50 % of iron in the form of hematite and 19. 40 % of zinc in the form of zincite. Most of the particles showed a spherical morphology of ~1 ?m in size. Using the time-reduced method, the following models were tested: (i) spherical interface-symmetry reaction model; (ii) exponential continuous reaction model; and (ii) unreacted core model. The results obtained showed a kinetic behavior with the combination of the first two models. At 800 and 950 °C the formation of zinc oxide needles was observed, in which was detected chloride and lead impurities. Mechanical behavior studies after the heat treatments showed that the pellets agglomerated with glucose syrup and Ca(OH)2 presented the best behavior at all temperatures.
Santos, Claudia Joanita. "Aplicação da polianilina contendo nanopartículas de zinco em revestimentos de carrocerias automotivas." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2957.
Full textThe protection against corrosion in the automotive industry is a high impact problem on the economic view. Besides of an antirust characteristic, the coatings used in the automotive industries needs to have a good appearance and phisical resistance. The multilayer coatings used normally are compound of e-coat, primer, base and clear coat, where the primer can also be used as an e-coat substitute in rework processes. In the other side, the conductive polymers has been widely discussed as an anti-rust coating material and the Polyaniline-zinc composite (PZn) had presented good results concerning the corrosion protection. Then, this study had applied the PZn in a multilayer coating used in the automotive industry, substituting the commercial primer in a common rework process. In addition, the PZn results were compared with the commercial primers used currently (FLASH and GLASURIT). To the material characterization, were done a MEV and EDS analysis of the substrate and were measured the coating thickness of the painted sets. To determinate the visual characteristics, were measured color, gloss and aspect. For corrosion, were performed electrochemical measurements (OCP and Tafel) and the cyclic test. Moreover, the phisical resistance were evaluated with humidity, flexibility and adherence tests: cross cut, steam jet, punctual impact and stone chip. The visual aspects results were similar for all the painted sets. For corrosion, the electrochemical tests presented similar results with the chemical test done by cycle test, in which the CJ_PANI and CJ_FLASH sets had showed them equivalent and the CJ_GLASURIT had better results, being the set more resistant. The phisical resistance could be divided in two types: dry and wet. The dry tests had similar results between the painted sets, but in the wet ones, the PZn set had presented susceptible for defects. In conclusion, the PZn composite had presented good results regarding visual aspects, electrochemical corrosion and dry technical tests when used in multilayer paint systems of the automotive industry. However, it presented a susceptible for defects in humidity environmental, losing adherence.
Petit, Fabien. "Contribution à l'étude de la réduction par plasma d'arc de fines oxydées contenant du plomb et du zinc." Limoges, 1997. http://www.theses.fr/1997LIMO0054.
Full textMerlin, Cécile. "Approches analytique et électrochimique de la dégradation des tôles d'acier revêtues cataphorésées en atmosphères corrosives contenant des ions sulfates." Nancy 1, 1999. http://www.theses.fr/1999NAN10286.
Full textJahed, Mohammed Nazeem. "The application of differential pulse anodic stripping voltammetry for the determination of copper, lead, zinc and cadmium in airborne particulate matter." Thesis, [S.l. : s.n.], 1995. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1007&context=td_ptech.
Full textHedroug, Karima. "Influence des chromates sur l'hydratation de la pate de ciment portland, durcissant au contact d'armatures galvanisees." Toulouse 3, 1987. http://www.theses.fr/1987TOU30192.
Full textCaovilla, Alessandra. "Catalisadores de zinco(II) e alumínio(III) contendo ligantes imina-pirrol e imina-fenolato aplicados na polimerização de lactídeos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/181332.
Full textThis work describes the preparation of novel ZnII and AlIII preprecatalysts containing pyrrole-imine or imine-phenolate as ligands and it’s structurally characterization by solution and solid-state techniques. The performance of the preprecatalysts were carried out through the ring-opening polymerization of rac- and L-lactide either in solution or in solvent-free (at 130°C) using an alcohol as co- initiator/chain-transfer agent (BnOH and iPrOH). Zinc bis-pyrrolide-imine precatalysts Zn1-Zn4 demonstrated the flexibility of the backbone structure, as well as the donor atom (oxygen versus sulfur), influence the activity of the polymerization. At 80 °C, the conversion of 100 equivalents of rac-lactide occurred within 24 h or 96 h, depending on the initiator, while only 1 h was required for high conversion under bulk conditions. When the ZnII bis-imine-phenolate Zn6 and Zn7 precatalysts were used, it was observed the formation of polymers with experimental molar mass values in good agreement with the calculated values, (according to the ratio []0:[]0) and with relatively narrow molar mass distribution were obtained in 180 min in toluene solution at 80 ° C. Also, the catalytic efficiency of Zn6 was evidenced in solvent-free reactions at 130 °C, mainly using 5 or 10 equivalents of benzyl alcohol. All ZnII bis-ligated systems, via activated monomer mechanism, leads to the formation of PLA with a slight heterotactic bias. AlIII pyrrolide-imine (Al5) and imine-phenolate (Al6-Al8) precatalysts, under bulk conditions, formed polymers with experimental molar mass values in good agreement with the calculated values, according to the ratio []0:[]0, and with relatively narrow molar mass distribution. Satisfactory results were observed for Al5 and Al6 precatalysts using toluene solution at 80 °C and 1 equivalent of benzyl alcohol. All the PLA polymers formed with the AlIII precatalysts tended to isoselectivity. The highest selectivity was obtained for the Al6 precatalyst which showed = 0.66 and =167 °C. With L-lactide monomer polymerization, conducted at 130 °C, the Al7 and Al8 precatalysts demonstrated that the activity was influenced by the nature of the alcohol (primary versus secondary alcohol). Independently of the monomer, it’s being proposed that the AlIII systems performed via coordination-insertion mechanism.
Badre, Chantal. "Etude de la réactivité de surface par mesure d'angle de contact : influence de la fonctionnalisation et de la structure : applications aux films d'oxyde de zinc électrodéposés." Paris 6, 2007. https://pastel.archives-ouvertes.fr/pastel-00004902.
Full textIn this work, we studied the surface reactivity by contact angle measurements. In our case, we were particularly interested in preparing textured surfaces with different roughness scales. Firstly, we have prepared smooth polyvinylchloride polymers acidified with lauric acid. Then, aerosil balls are added to create some roughness on the polymer. Controlling the roughness and the morphology of these polymers remain a main disadvantage that leaded us to use other materials with easier roughness control like Zinc Oxide (ZnO). Different morphologies were prepared by electrodeposition such like nanorods and nanowires. It is well known that the wettability of ZnO can be modified by applying the bottom-up process. We used self assembled layers (SAMs) of organic molecules like octadecylsilane and fatty acids. We succeeded to prepare superhydrophobic surfaces with the highest contact angle 176° ever obtained on ZnO. The study was extended and ferrocene probe molecules were used
Cohen, Serge. "Détermination et étude de la structure d'un nouveau module se fixant à l'ADN et contenant du zinc : le domaine GCM." Université Joseph Fourier (Grenoble), 2002. http://www.theses.fr/2002GRE10173.
Full textFaÿ, Sylvie Shah Arvind V. Shah Arvind V. Shah Arvind V. "L'oxyde de zinc par dépôt chimique en phase vapeur comme contact électrique transparent et diffuseur de lumière pour les cellules solaires /." [S.l.] : [s.n.], 2003. http://library.epfl.ch/theses/?display=detail&nr=2899.
Full textRomero, João Henrique Saska. "Propriedades ópticas e estruturais de hidróxidos duplos lamelares luminescentes contendo zinco, alumínio, európio e ligantes orgânicos /." Araraquara, 2017. http://hdl.handle.net/11449/150013.
Full textBanca: Édson Pecoraro
Banca: Fernando Aparecido Sigoli
Banca: Vera Regina Leopoldo Constantino
Banca: Sérgio Antonio Marques de Lima
Resumo: O desafio da Química no século XXI é a obtenção de materiais promissores em aplicações e perspectivas inovadoras. Um ótimo candidato para estudos específicos é a síntese de materiais luminescentes bidimensionais. Entre as matrizes bidimensionais disponíveis, pode-se destacar os Hidróxidos Duplos Lamelares (HDLs) sintetizados no laboratório por rotas simples e de baixo custo, que têm como fórmula geral [M2+(1-x)M'3+x(OH)2](An-)x/n.zH2O (M, M' = íons metálicos que constituem as lamelas, e An- = ânion interlamelar). Preparou-se as amostras pelo método de coprecipitação e troca iônica. Na primeira etapa do trabalho otimizou-se os parâmetros de síntese. Após, obteve-se as amostras [Zn2Aℓ1-xEux(OH)6]A·zH2O-HDL (A = NO3- ou Cℓ- e x = 0,1 ou 1 ou 5 ou 10% em mol) e a fase formada é de HDL, conforme dados de XRD. O perfil de luminescência indica sítios de baixa simetria, emissão com alta pureza de cor e, que alta concentração de grupos -OH intensifica os processos não-radiativos diminuindo a eficiência quântica. Na segunda etapa do trabalho, as amostras [Zn2Aℓ1-xEux(OH)6]A·zH2O-HDL (A = bca (4-ácido-bifenilcarboxílico) ou acac (acetilacetona) ou tta (2-tenoiltrifluoroacetona) obtidas pelo método de coprecipitação não formam a estrutura lamelar. Assim, optou-se pelo método de troca iônica para as amostras [Zn2Aℓ1-xEux(OH)6]A·zH2O-HDL (A = bca, bpdc (4,4-ácido-bifenildicarboxílico), tta e acac e x = 0,1% em mol). A intercalação das espécies aniônicas na matriz HDL nas condições utiliza... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The challenge of chemistry in the 21st century has being the study of promising materials for applications and innovative perspectives. A great example is the synthesis of two-dimensional luminescent materials. Among the available structures, it can be highlighted Layered Double Hydroxides (LDH) synthetized in the laboratory by simple route and low cost. LDH have the general formula [M2+(1-x)M'3+x(OH)2](An-)x/n.zH2O (M, M' = layer metal ions, and An- = interlayer anion). The samples have been prepared by co-precipitation or ion exchange method. In the first stage, several experimental steps have performed to acquire the better synthesis parameters. Then, [Zn2Aℓ1-xEux(OH)6]A·zH2O-LDH (A = NO3- or Cℓ- and x = 0.1 or 1 or 5 or 10 at.%) samples were achieved according to XRD data. Luminescent properties indicate low-symmetry sites, emission with high color purity, and low quantum yield due to the high -OH groups concentration that enhances the non-radiative processes. In the second step, attempts to prepare [Zn2Aℓ1-xEux(OH)6]A·zH2O-LDH (A = bca (biphenyl-4-carboxylic acid) or acac (acetylacetone) or tta (2-thenoyltrifluoroacetone) by co-precipitation method did not lead to a LDH structure. Thus, it has been chosen the ion exchange method to prepare [Zn2Aℓ1-xEux(OH)6]A·zH2O-LDH (A = bca, bpdc (biphenyl-4,4′-dicarboxylic acid), tta e acac e x = 0.1 at.%) samples. Anionic species intercalation into LDH under the used conditions is efficient to the bca and is limited to th... (Complete abstract click electronic access below)
Doutor
Kenmoe, Stephane [Verfasser], Jörg [Gutachter] Neugebauer, and Ralf [Gutachter] Drautz. "Ab initio study of the low-index non-polar Zinc oxide surfaces in contact with water / Stephane Kenmoe ; Gutachter: Jörg Neugebauer, Ralf Drautz." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1121909388/34.
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