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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Measurement, Characterization, and Source Apportionment of the Major Chemical Components of Fine Particulate Material, Including Semi-Volatile Species

Grover, Brett D. 16 February 2006 (has links) (PDF)
The promulgation of revised standards for atmospheric fine particles (PM2.5) by the US EPA has sparked renewed interest in the ability to accurately measure and characterize suspended atmospheric particulate matter. Semi-volatile material (SVM), consisting of ammonium nitrate and semi-volatile organic material (SVOM), is not accurately measured by EPA accepted methods such as the Federal reference method (FRM) or Tapered Element Oscillating Microbalance (TEOM). However, SVM is often a major fraction of urban aerosols. Recent advances in atmospheric sampling instrumentation allowed for the semi-continuous characterization of urban PM2.5, including SVM. The Filter Dynamic Measurement System (FDMS) was shown to measure total PM2.5 mass including semi-volatile species. Validation of the FDMS was performed by comparison with the particle concentrator-Brigham Young University organic sampling system (PC-BOSS) and the real-time total ambient mass sampler (RAMS). Semi-continuous ambient particulate concentrations of sulfate, nitrate and ammonium ion were measured by a newly developed Dionex instrument which was field tested and validated for the first time in Fresno, CA. Either a modified Sunset Laboratory carbon monitor, collocated with a conventional Sunset carbon monitor employing a common inlet, or the newly developed dual-oven Sunset monitor allowed for the semi-continuous determination of both nonvolatile and semi-volatile organic material. This was the first attempt to characterize both nonvolatile and semi-volatile fractions of an urban aerosol in a semi-continuous manner using all semi-continuous instruments. A suite of instruments for semi-continuous PM2.5 monitoring was recommended including, an R&P FDMS for the measurement of PM2.5 mass, a dual-oven Sunset monitor for the measurement of nonvolatile and semi-volatile carbonaceous species, and a Dionex GP-IC for the measurement of inorganic species. A TEOM monitor is also recommended to measure nonvolatile PM2.5 mass. Using these instruments, semi-continuous mass closure was obtained for the first time during a study conducted in Riverside, CA. The advantage of using semi-continuous sampler data in the application of source apportionment was elucidated. Local aerosols are often impacted by short-term pollution episodes that cannot be temporally resolved using integrated samplers. One-h averaged data applied to source apportionment models was shown to increase the power of the model to predict sources, both primary and secondary, that exhibit diurnal short-term episodes.
82

eco-Technoeconomic-Analysis of Steel Manufacturing Off-gas Valorization

DENG, LINGYAN January 2020 (has links)
The steel manufacturing industry is one of the largest emitters of CO2, accounting for upwards of 8.8% of all anthropogenic CO2 emissions. The governments are charging taxes on CO2 emissions, which incentivize the industry to further reduce CO2 emissions. At present, much of the CO2, produced in the steel manufacturing process occurs as a result of coke oven and blast furnace gas by-products. As such, two major strategies have been proposed to reduce steel-manufacturing-related CO2 emissions: producing more electricity via optimized combined cycle power plants (CCPP), and converting off-gas by-products into methanol (CBMeOH). The present research consists of an economic and environmental analysis of the status quo, CCPP, and CBMeOH systems for five locations: Ontario, the USA, Finland, Mexico, and China. The economic analysis considered factors such as carbon tax, electricity price, methanol price, electricity carbon intensity, power purchasing parity, and income tax. In the CCPP process, desulphurization is conducted using ProMax with MDEA as the solvent, while the CBMeOH process uses a membrane to separate the bulk H2S, with organic sulfurs such as thiophene being removed via CO2+steam reforming and middle-temperature removal. The results of the economic analysis revealed the CBMeOH plant to be the most profitable in Ontario, the USA, China, and Mexico, while the CCPP system was shown to be the most profitable in Finland. The environmental analysis was conducted using the TRACI, CML-IA, ReCiPe2016, and IMPACT2002+ tools in SimaPro V9, with the results showing the CBMeOH system to be the most environmentally option in Ontario, Finland, and China, and the CCPP system as the most environmentally friendly option in the USA and Mexico. / Dissertation / Doctor of Philosophy (PhD)
83

Uticaj kvaliteta semenki grožđa na bioaktivne komponente i održivost hladno presovanog ulja / Impact of grape seed quality on bioactive components and stability of cold pressed oil

Bjelica Miloš 27 September 2019 (has links)
<p>Podizanje novih zasada i povećanje kapaciteta prerade<br />grožđa povećava količinu otpada sa kojim se suočava<br />industrija proizvodnje vina i rakije. Najbolji i najodgovorniji<br />način upravljanja otpadom je njegovo dalje iskori&scaron;ćenje<br />kao nusproizvoda. U ovoj disertaciji sagledavana je mogućnost iskori&scaron;ćenja<br />nusproizvoda iz različitih faza proizvodnje u vinarijama i<br />destilerijama za dobijanje semenki grožđa koje su<br />kori&scaron;ćene za proizvodnju hladno presovanog ulja. Hipoteza<br />se zasniva na činjenici da semenke grožđa raznih sorti iz<br />različitih faza proizvodnje vina (bela, roze ili crvena vina),<br />odnosno, rakije mogu imati sasvim različit hemijski sastav i<br />kvalitet koji svakako može da se reflektuje na kvalitet,<br />bioaktivne komponente i održivost hladno presovanog ulja.<br />Ovakav proizvod, obzirom da je dobijen hladnim<br />presovanjem, može biti veoma atraktivan za potro&scaron;ače,<br />zbog svojih specifičnih senzorskih i nutritivnih<br />karakteristika.<br />Za potrebe izrade disertacije prikupljeni su nusproizvodi<br />i pripremljeni su uzorci iz vinarija i destilerija fru&scaron;kogorskog<br />vinogorja. Dobijene su semenke i proizvedeno hladno<br />presovano ulje od semenki crnog grožđa sorte Merlot,<br />belog grožđa sorte Italijanski rizling i belog grožđa sorte<br />Sila, kao autohtone sorte vinove loze. Hladno presovana<br />ulja su proizvedena od semenki grožđa koje nisu pro&scaron;le<br />nikakav tretman, odnosno dobijene su nakon presovanja,<br />prilikom proizvodnje belih (Italijanski rizling i Sila) i roze<br />(Merlot) vina, zatim od semenki koje su pro&scaron;le proces<br />fermentacije prilikom proizvodnje crvenih vina (Merlot) i od<br />semenki koje su pro&scaron;le proces fermentacije i destilacije<br />prilikom proizvodnje rakije (Merlot, Italijanski rizling i Sila).<br />Pored navedenih semenki i ulja, pripremljen je i prosečan<br />proizvodni uzorak koji predstavlja uzorak dobijen od svih<br />prikupljenih semenki. Kao uporedni uzorci kori&scaron;ćeno je<br />nerafinisano i rafinisano ulje od semenki grožđa nabavljeno<br />na trži&scaron;tu. Za realizaciju postavljenog cilja, rad na izvođenju ove<br />disertacije obuhvatio je različite faze. U prvoj fazi<br />prikupljene su semenke grožđa i ispitivane su njihove<br />tehničko-tehnolo&scaron;ke karakteristika i kvalitet. Zatim su od<br />navedenih semenki proizvedena hladno presovana ulja.<br />U sledećim fazama, ovako dobijena uja, zajedno sa<br />uzorkom nerafinisanog i rafinisanog ulja od semenki<br />grožđa sa trži&scaron;ta ispitivana su sa aspekta senzorskog i<br />nutritivnog kvaliteta i praćene su razlike u održivosti ulja.<br />Izvr&scaron;ena je senzorska analiza, određivane su frakcije<br />pigmenata, karotenoidi i hlorofili, merena je transparencija,<br />a parametri boje ulja određivani su i instrumentalno.<br />Nutritivni kvalitet ulja sagledavan je na osnovu sadržaja i<br />sastava bioaktivnih komponenti, pre svega tokoferola i<br />tokotrienola, fenola i sterola. Budući da ova jedinjenja<br />ispoljavaju značajne antioksidativne aktivnosti izvr&scaron;eno je i<br />ispitivanje antiradikalske aktivnosti uzoraka. Odživost ulja<br />od semenki grožđa sagledana je na osnovu početnog<br />kvaliteta i oksidativnog stanja, kao i rezultata ubrzanih<br />testova, kao &scaron;to je Rancimat test, Schaal-oven test i<br />fluorescentni test.<br />Na osnovu dobijenih rezultata, može se konstatovati da<br />su svi dobijeni uzorci semenki imali dobru skladi&scaron;nu vlagu,<br />koja, obzirom na mali sadržaj ulja u semenkama, može da<br />osigura čuvanje semenki u dužem periodu. Sadržaj ulja u<br />semenkama, pored uticaja sorte vinove loze, zavisi i od<br />uticaja procesa kome su podvrgnute semenke pre<br />presovanja (fermentacija, destilacija).<br />Senzorska analiza ulja od semenki grožđa pokazala je<br />značajne razlike u karakteristikama koje su posledica ne<br />samo načina dobijanja ulja (hladno presovano ili rafinisano), sorte vinove loze, već i postupka dobijanja,<br />porekla i kvaliteta semenki grožđa. Uslovi kojima su<br />semenke grožđa izložene u toku alkoholne fermentacije i<br />posebno destilacije utiču na formiranje specifične arome<br />hladno presovanog ulja. I pored toga &scaron;to se pojavljuje<br />izuzetno &scaron;irok spektar različitih aroma, mirisa i ukusa u ulju<br />i &scaron;to postoje značajne razlike u aromi ulja u zavisnosti od<br />sorte grožđa, moguće je prepoznati da li je hladno<br />presovano ulje dobijeno od semenki grožđa bez<br />fermentacije, posle fermentacije ili posle destilacije.<br />Takođe, sa aspekta boje ulja može se kazati da rafinisano<br />ulje od semenki grožđa ima svetlo žutu boju sa<br />zelenkastom nijansom, dok su hladno presovana ulja<br />intenzivnijih boja i kreću se od žuto-zelenkaste, preko<br />zelenkasto žute i svetlo zelenkaste do tamno zelene. Veći<br />udeo zelene boje imaju hladno presovana ulja od semenki<br />grožđa dobijenih posle destilacije.<br />U radu je pokazano da sadržaj pigmenata (karotenoida i<br />hlorofila) u velikoj meri zavisi od porekla semenki.<br />Postupak fermentacije doprinosi povećanju sadržaja<br />pigmenata, dok postupak destilacije, zbog visokih<br />temperatura ima negativan efekat.<br />Transparencija uzoraka hladno presovanih ulja od<br />semenki grožđa proizvedenih za potrebe disertacije kretala<br />se od 32,8% do 53,8%.<br />Sadržaj nezasićenih masnih kiselina u svim uzorcima<br />ulja od semenki grožđa veći je od 90%, pri čemu<br />dominantnu masnu kiselinu čini linolna, omega-6, masna<br />kiselina.<br />Sadržaj tokotrienola je veći od sadržaja tokoferola u uljima od semenki grožđa, a dominantni tokoferol je alfatokoferol.<br />Njegov sadržaj je veći u uzorcima ulja dobijenim<br />iz semenki nakon fermentacije i destilacije.<br />Sadržaj fenolnih jedinjenja, u zavisnosti od sorte, u<br />proseku je ne&scaron;to vi&scaron;i u hladno presovanim uljima dobijenim<br />od crvene sorte grožđa, ali uočava se i značajan porast<br />(akumulacija) fenola u hladno presovanim uljima dobijenim<br />iz semenki grožđa nakon procesa fermentacije i destilacije.<br />Najveći pojedinačni sadržaju u ulju od semenki grožđa ima<br />ursolna kiselina, a pored nje značajniji sadržaj, mada<br />mnogo manji, pokazuju rezveratrol, kemferol i vanilinska<br />kiselina.<br />Najzastupljeniji steroli ulja semenki grožđa su &beta;-<br />sitosterol sa udelom od 62,59-69,74%, stigmasterol sa<br />udelom od 12,13-15,00% i kampesterol sa udelom od 6,59-<br />11,94% u ukupnim sterolima. Na sadržaj fitosterola u<br />uljima od semenki grožđa nemaju uticaja procesi<br />fermentacije i destilacije kojima su podvrgnute semenke<br />pre preosvanja.<br />U radu je dokazan negativan uticaj procesa fermentacije<br />i destilacije kojima su povrgnute semenke grožđa na<br />antiradikalski potencijal dobijenih ulja. Antiradikalski<br />potencijal ulja od semenki grožđa zavisi i od sorte vinove<br />loze, kao i od načina dobijanja ulja (hladno presovano ili<br />rafinisano).<br />Procesi fermentacije i destilacije utiču i na osnovni<br />hemijski kvalitet dobijenih hladno presovanih ulja na način<br />da dovode do povećanja kiselinskog i peroksidnog broja.<br />Hladno presovana ulja od semenki grožđa pokazuju<br />dobru oksidativnu stabilnost. Rancimat test je pokazao razlike u indukcionom periodu hladno presovanih ulja od<br />semenki grožđa kao posledicu razlike u sorti, kao i u<br />načinu dobijanja semenki. Proces fermentacije utiče na<br />povećanje, a proces destilacije na smanjenje indukcionog<br />perioda.<br />Na osnovu svih dobijenih rezultata istraživanja može se<br />konstatovati da su hladno presovana ulja od semenki<br />grožđa pokazala različit nutritivni kvalitet i oksidativnu<br />stabilnost, zbog specifičnih razlika koje su posledica razlika<br />u sorti i poreklu semenki, tj. zbog specifičnog efekta<br />fermentacije i destilacije na semenke od kojih je ulje<br />proizvedeno, čime je i potvrđena hipoteza.</p> / <p>Raising new plantations and increasing the grape<br />processing capacity increases the amount of waste faced<br />by the wine and brandy industry. The best and most<br />responsible way of waste management is its further<br />exploitation as by-products.<br />In this dissertation, the possibility of using by-products from different stages of production in wineries and distilleries for<br />obtaining grape seeds, which were used for the production<br />of cold pressed oil, was examined. The hypothesis is<br />based on the fact that grape seeds of various varieties<br />from different stages of wine production (white, rose or red<br />wine), that is, brandy can have a completely different<br />chemical composition and quality that can certainly be<br />reflected on the quality, bioactive components and stability<br />of cold pressed oil.<br />Such a product, as it is obtained by cold pressing, can<br />be very attractive to consumers, due to its specific sensory<br />and nutritional characteristics.<br />For the needs of the dissertation, the by-products were<br />collected and samples were prepared from the wineries<br />and distilleries of the Fru&scaron;ka Gora vineyard. Seeds were<br />obtained and cold pressed oil produced from Merlot grape<br />seed, as representatives of red grape varieties, Italian<br />Riesling, as representatives of white grape varieties and<br />Sila, as new white grape varieties. Cold pressed oils were<br />produced from grape seeds that did not undergo any<br />treatment, that is, they were obtained after pressing, during<br />the production of white (Italian Riesling and Sila) and rose<br />(Merlot) wines, then from the seeds that were fermented<br />during the production of red wines (Merlot ) and seeds that<br />have undergone fermentation and distillation process<br />during the production of brandy (Merlot, Italian Riesling and<br />Sila). In addition to the mentioned seeds and oils, an<br />average production sample was prepared, which is a<br />sample obtained from all collected seeds. Unrefined and<br />refined grape seed oil purchased on the market was used<br />as comparative samples. For realization of the set goal, the work on the<br />performance of this dissertation encompassed different<br />phases. In the first phase, grape seed were collected and<br />their technical and technological characteristics and quality<br />were examined. Then cold-pressed oils were produced<br />from these seeds.<br />In the following phases, the resulting ear, together with a<br />sample of unrefined and refined grape seed oil from the<br />market, were examined from the aspect of sensory and<br />nutritional quality and differences in oil stability were<br />observed. Sensory analysis was performed, pigmentate<br />fractions, carotenoids and chlorophylls were determined,<br />transparency was measured, and oil color parameters<br />were also determined instrumentally. The nutritive oil<br />quality was examined based on the content and<br />composition of bioactive components, primarily tocopherols<br />and tocotrienols, phenols and sterols. Since these<br />compounds exhibit significant antioxidant activities, the<br />antiradical activity of the samples was also tested. The<br />stability of grape seed oils was examined based on the<br />initial quality and the oxidative state, as well as the results<br />of accelerated tests, such as Rancimat test, Schaal-oven<br />and fluorescence test.<br />On the basis of the obtained results, it can be concluded<br />that all the obtained seed samples had good storage<br />moisture, which, given the small content of oil in the seeds,<br />can ensure the storage of seeds for a longer period. The<br />content of oil in the seed, in addition to the influence of the<br />grape variety, depends on the influence of the process to<br />which the seeds are subjected to pressing (fermentation,<br />distillation). Sensory analysis grape seed oils showed significant<br />differences in characteristics that are due not only to the<br />method of obtaining oil (cold pressed or refined), grape<br />varieties, but also the method of obtaining, the origin and<br />quality of grape seed. The conditions for grape seeds<br />exposed during fermentation and especially distillation<br />affect the formation of a specific cold pressed oil. Although<br />an extremely wide range of different flavors, odors and<br />flavors in oil appear, and there are significant differences in<br />the aroma of the oil, depending on the grape variety, it is<br />possible to recognize whether the cold-pressed oil is<br />derived from the grape seed without fermentation, after<br />fermentation or after distillation. Also, from the aspect of oil<br />color it can be said that refined grape seed oil has a light<br />yellow color with a greenish shade, while cold pressed<br />grape seed oils have more intense colors range from<br />yellowish-greenish, over greenish yellow and light greenish<br />to dark green. A higher proportion of green color has cold<br />pressed grape seed oils obtained after distillation.<br />The thesis has shown that the content of pigments<br />(carotenoids and chlorophyll) depends to a great extent on<br />the origin of the seed. The fermentation process<br />contributes to increasing the content of pigments, while the<br />distillation process has a negative effect due to high<br />temperatures.<br />Transparency of cold pressed grape seed oils produced<br />for the dissertation ranged from 32.8% to 53.8%.<br />The content of unsaturated fatty acids in all samples of<br />grape seed oil is greater than 90%, with the dominant fatty<br />acid being linoleic, omega-6, fatty acid. The content of tocotrienols is higher than the content of<br />tocopherols in grape seed oils, and the dominant<br />tocopherol is alpha-tocopherol. Its content is higher in oil<br />samples obtained from the seed after fermentation and<br />distillation.<br />The content of phenol compounds, depending on the<br />variety, is somewhat higher in cold pressed oils obtained<br />from red grape varieties, but there is also a significant<br />increase in accumulation of phenol in cold pressed oils<br />obtained from the grape seed after the fermentation and<br />distillation process. The largest individual oil content of<br />grape seeds has ursolic acid, and besides it, significant<br />content, although much smaller, shows rezveratrol,<br />kemferol and vanillinic acid.<br />The most prevalent sterols of grape seed oils are &beta;-<br />sitosterol with a share of 62.59-69.74%, stigmasterol with a<br />share of 12.13-15.00% and campesterol with a share of<br />6.59-11.94% in total sterols. Fermentation and distilation<br />processes, to which the seeds have been exposed, have<br />no effect on the content of phytosterols in grape seed oils.<br />The paper has shown the negative influence of the<br />fermentation and distillation process, to which the seeds<br />have been exposed, onto the antiradical potential of the<br />obtained oils. The antiradical potential of grape seed oils<br />depends on grape varietes, as well as on the way oil is<br />obtained (cold pressed or refined).<br />Processes of fermentation and distillation also affect the<br />basic chemical quality of obtained cold pressed oils in such<br />a way as to increase the acid and peroxide values.<br />Cold pressed grape seed oils show good oxidative stability. The Rancimat test showed differences in the<br />induction period of cold pressed grape seed oils as a result<br />of the variation in the variety, as well as in the method of<br />obtaining the seed. The fermentation process affects the<br />increase, and the process of distillation decreases the<br />induction period.<br />Based on all the obtained results, it can be concluded<br />that cold pressed grape seed oils showed different<br />nutritional quality and oxidative stability due to specific<br />differences resulting from differences in variety and seed<br />origin, i.e. due to the specific effect of fermentation and<br />distillation processes on the seeds from which the oil was<br />produced, thus confirming the hypothesis.</p>
84

Design and development of an automated temperature controller for curing ovens

Schoeman, Ruaan Mornè 12 1900 (has links)
Thesis (M. Tech. - Engineering: Electrical, Department Electronic Engineering, Faculty of Engineering and Technology)--Vaal University of Technology. / Curing of materials in order to obtain different properties has been a practice for many years. New developments in composite materials increase the need to control certain variables during the curing process. One very significant variable is temperature. Temperature control by itself is an old practice, however when the need for repeatedly controlling the process accurately over long periods of time arises, a system is required that outperforms normal manual control. One of the aspects within such a system that needs to be considered is the ability to replicate the temperatures within an oven which were originally used for a specific material’s curing profile. This means that a curing profile would need to be defined, saved for later and finally be interpreted correctly by the controlling system. Different control methods were simulated to enable the system to control the temperature which has been defined by literature. This dissertation introduces a variation on the standard control methods and shows improved results. Switching the oven on and off in order to increase or decrease internal oven temperature seems simple, but can cause switching devices to decrease their operational life span, if not designed carefully. A combination switch was introduced which harnesses the advantages of two very common switching devices to form an improved combination switch. Software for the personal computer environment, as well as software for the embedded environment were developed and formed a control system that produced acceptable results for temperature control. Accuracies of 98% and more were achieved and found to be acceptable according to standard engineering control practices. An accurate temperature profile controller was designed, simulated and built in order to control the temperature inside a specific curing oven which, in turn, determined the curing properties of specific materials. The overall results were satisfactory which lead to achieving the objectives outlined in this dissertation.
85

"Avaliação da alteração dimensional da base de prova permanente da prótese total de resina acrílica ativada termicamente, processada em forno microondas, por meio da imagem digital" / Evaluation of the dimensional alteration according to the permanent proof base for complete denture made of thermally activated acrylic resin, in microwave process, using digital image

Lima, Ana Paula Barbosa de 11 August 2006 (has links)
Foram confeccionados 50 corpos de prova, divididos em 30 próteses totais superiores e 20 bases de provas permanentes, padronizados, para se avaliar a alteração dimensional da base de prova permanente, com dupla polimerização, processada em forno de microondas convencional; base de prova permanente com dupla polimerização, processada no método convencional; e a prótese total em uma única polimerização. Para essa análise, essas próteses foram divididas em 5 grupos: grupo I – prótese total convencional – banho de água (controle); grupo II – base de prova permanente processada convencionalmente; grupo III – base de prova permanente processada em forno de microondas convencional; grupo IV – prótese total superior padronizada com base de prova permanente processada convencionalmente, com as bases do grupo II; grupo V – prótese total superior com base de prova permanente, processada no forno de microondas convencional, com as bases de prova do grupo III. Para avaliar essa alteração foi usado o recurso do scaneamento da região posterior das próteses, “Post-dam", desses corpos de prova. Após esse processo, a imagem capturada foi levada para o programa Photoshop 8.0 determinando a região de avaliação. Após essa seleção, a imagem é acessada no CorelTrace 11 para ser transformada em preto e branco e vetorizada, sendo, então, levada para o CorelDraw 11 para ser feita a medição do espaço da região posterior, entre o modelo e a base de prova/prótese total, para permitir a análise dos valores da alteração dimensional dos corpos de prova em questão, após o processamento. Os resultados mostram que: 1) a diferença da variação média para os lados esquerdo, centro e direito, respectivamente, na ordem de décimos ou centésimos de milímetros, para o grupo IV e I (0,07; 0,08 e 0,09); para o grupo V e I (0,10; 0,32 e 0,25) e para o grupo V e IV (0,17; 0,24 e 0,16) não pode ser considerada relevante clinicamente para afetar o ajuste da prótese na boca e promover a ocorrência de maiores transtornos clínicos; 2) A alteração média das áreas do lado esquerdo e direito para o grupo I, II e IV obtiveram uma homogeneidade na alteração, diferindo os Grupos III e V em relação aos outros, não existindo porém, diferença significante a nível de 5% entre as áreas desses segmentos; 3) A análise da variância do índice da área dos cinco (5) grupos não apresentou resultado significante que desabonasse a utilização de qualquer um dos métodos para a confecção da prótese total. No entanto, mais estudos devem ser realizados com o intuito de se aprimorar o uso do forno de microondas para o processamentos da prótese. / The 50 samples of pattern maxillary complete denture were processed, divided in 30 maxillary complete denture and 20 permanent proof base, to evaluated of dimensional changes in the permanent proof base with twice polymerization, process in microwave oven, to compare with the others two groups, the complete denture with conventional process and the complete denture with permanent proof base with twice polymerization in a conventional process. To evaluated this complete dentures they were divided in 5 groups: group I – conventional complete denture; group II – proof base conventional process; group III – proof base in microwave process; group IV – complete denture using the proof base of the group, with the conventional process and the group; group V – complete denture using the proof base of the group III, microwave process. To evaluated this alteration used the scanner in the “Post-dam", in this samples. After this proceding the image was putting in the Adobe Photoshop 8.0 program to determinate what region was evaluated. After this selection, the image access in the CorelTrace 11 program and transformed in black and white, and after to access in the CorelDraw 11 that was measured the region between the cast and the complete/permanent proof base, to allow the analysis of the values the dimensional alteration of the proof body, after the process. The results show: 1) The linear dimensional alteration the difference mean variation for the left, center and right sides, respectively, it was in decimal order or centesimal of millimeters, for the group IV and I (0,07; 0,08 and 0,09); and for the group V and I were (0,10; 0,32 and 0,25) and for the group V and IV (0,17; 0,24 and 0,16) and it cannot be considered clinically relevant to affect the prosthesis adjustment in the mouth, and promote the occurrence of more clinical disruptions; 2) The dimensional alterations in the areas (left and right side) of the proof bodies of the three groups I, II and IV were uniform, and the groups III and V weren’t homogeneous, but there is not a statically significant difference, about 5%, between the segment left and right areas; 3) The variation of the area index about five groups there is not a statically significant that couldn’t use of the both method to build the complete denture. Although, more studies are important to realize with the objective to improve the use the microwave over to process the denture.
86

Estudo das sínteses de peptídeos em fase sólida passo a passo e convergente a 60 °C usando aquecimento convencional e micro-ondas / Study of stepwise and convergent solid-phase peptide syntheses at 60ºC using conventional and microwave heatings

Loffredo, Carina 21 December 2009 (has links)
É sabido que: (i) as sínteses individual e múltipla (manual e automática), bem como a construção de bibliotecas e micro-arranjos de peptídeos sintéticos empregam a metodologia da fase sólida (SPFS); (ii) apesar do desenvolvimento atual desta metodologia sintética, os químicos de peptídeos continuam se deparando com problemas e limitações inerentes a ela; (iii) muitos trabalhos relatam a sua agilização pelo uso de altas temperaturas, mas poucos revelam preocupação com a integridade quiral dos peptídeos-alvo. Portanto, o presente trabalho objetivou dar continuidade à nossa investigação pioneira das: 1) incidência da enantiomerização dos aminoácidos e/ou de outras reações secundárias nas SPFS passo a passo de peptídeos a 60 °C; 2) viabilidade de realização de todas as etapas da síntese convergente em fase sólida (SCPFS) a 60 °C. Em relação ao tópico 1, os peptídeos-alvo escolhidos tinham tamanho e sequência variáveis que incluiam os aminoácidos trifuncionais problemáticos Cys, Ser, His, Met e Trp. Todos eles foram obtidos por SPFS passo a passo convencional e a 60 °C usando aquecimento convencional e micro-ondas. A identificação e a quantificação dos isômeros contaminantes foram feitas com a ajuda de padrões resultantes da SPFS passo a passo convencional e de métodos analíticos (RP-HPLC, LC-ESI/MS, CE e análise quiral de aminoácidos) em condições estabelecidas por nós. Foi constatado que: (i) as nossas condições de acoplamento são mais econômicas que as usuais, pois empregam menor concentração e excesso molar de N-acil-aminoácidos; (ii) nelas, a SPFS a 60 °C usando o aquecimento convencional é simples, prática, de custo relativamente baixo, demanda ½ do tempo da SPFS convenciona e não compromete significativamente a integridade quiral dos aminoácidos; (iii) nas condições similares, a SPFS passo a passo a 60 °C assistida por micro-ondas é mais rápida (realizada em ¼ do tempo gasto na SPFS convencional), porém mais cara e acompanhada de aumento significativo da enantiomerização da Cys; (iv) a mistura 25% DMSO/tolueno, nunca antes utilizada na SPFS assistida por micro-ondas, favoreceu a formação de contaminantes contendo Met oxidadas a sulfóxidos durante as sínteses do fragmento CCK24-33NS, mas o mesmo ocorreu quando DMF foi usado nas sínteses da CCK-33 NS; (v) outras reações secundárias típicas da SPFS passo a passo não foram intensificadas significativamente nas nossas condições sintéticas a 60 °C. Quanto ao tópico 2, foi escolhida a CCK-33 NS como modelo peptídico. Foi constatado que: (i) a etapa de obtenção dos fragmentos peptídicos protegidos que atuariam como doadores de acila (D.A.) e aceptor de acila (A.A.) de partida pode ser ágil e bem sucedida pela SPFS passo a passo a 60 °C nas nossas condições experimentais usando o aquecimento convencional; (ii) DMF, NMP e 25% DMSO/Tolueno foram adequados à solubilização dos fragmentos D.A. e dos reagentes necessários à sua ativação a 60 °C; (iii) a 60 °C, tais solventes também intumesceram satisfatoriamente a CCK24-33NS-resina Rink amida, A.A. de partica; (iv) o aquecimento convencional permitiu que algumas reações de acoplamento entre os D.A. e A.A. escolhidos fossem realizadas com sucesso; na maioria dos casos em que isso não ocorreu, o uso combinado das micro-ondas e agitação sob atmosfera inerte mediaram a formação do produto desejado; (v) a natureza dos fragmentos D.A. e A.A. é fator limitante na SCPFS, mesmo a 60 °C e usando o aquecimento convencional ou as micro-ondas, e, portanto, ele precisa ser melhor estudado. / It is well known that: (i) individual and multiple peptide syntheses (manual and automatic) as well as construction of synthetic peptide libraries and micro-arrays are all based on solid phase chemistry (SPPS); (ii) despite the current development of such synthetic methodology, peptide chemists are still facing its problems and inherent limitations; (iii) many previous works employed high temperatures to accelerate stepwise SPPS, but only a few showed concern about the preservation of the chiral integrity of the target peptide. Therefore, the main goal of the present work was to continue our pioneering investigation of: 1) the incidence of amino acids enantiomerization and/or other side-reactions in the stepwise SPPS at 60°C, 2) the viability of performing all steps of the convergent synthesis on a solid support (CSPPS) at 60°C. With regard to the topic 1, the peptides chosen as targets had variable size and sequence, which included the tricky trifunctional amino acids Cys, Ser, His, Met and Trp. The peptides were synthesized by conventional stepwise SPFS and at 60 °C using conventional or microwave heating. Identification and quantification of the contaminant isomers was done with the aid of standards resultant from conventional stepwise SPPS and of analytical methods (RP-HPLC, LC-ESI/MS, CE and chiral amino acids analysis) in conditions established in our laboratory. It was shown that: (i) our coupling conditions are cheaper than the usual ones as they employ lower concentration and excess of N-acyl-amino acids; (ii) under them, stepwise SPPS at 60 °C using the conventional heating is simple, practical, relatively low-cost, demands half of the time required by conventional stepwise SPPS and does not cause the enhancement of amino acids enantiomerization; (iii) under similar conditions, microwave-assisted stepwise SPPS at 60 °C is faster (it demands only one-fourth of the time spent in the conventional stepwise SPPS), but it is more expensive and causes significant damage specially to the chiral integrity of Cys; (iv) the binary mixture 25% DMSO/toluene, never used earlier in microwave-assisted stepwise SPPS, led to the formation of contaminants with Met oxidized to its sulfoxides during the synthesis of CCK24-33NS; however, it also occurred when DMF was used in the synthesis of CCK-33 NS; (v) other side reactions typical of stepwise SPPS were not significantly intensified under our conditions at 60 °C. Concerning to the topic 2, CCK-33 NS was chosen as the model peptide. It was shown that: (i) the synthesis of the protected peptides that would act as acyl donor (A.D.) or as the starting acyl aceptor (A.A.) can be fast and successfully achieved at 60 °C under our experimental conditions using conventional heating; (ii) DMF, NMP and 25% DMSO/toluene dissolved all A.D. and the reagents required for their activation at 60 °C; (iii) at this temperature, such solvents were also able to properly swell CCK24-33NS-Rink amide resin, the starting A.A.; (iv) the conventional heating allowed for some coupling reactions between A.D. and A.A., but in most cases in which it did not occur, the combined use of microwaves and stirring under inert atmosphere mediated the formation of the desired products; (v) the nature of fragments A.D. and A.A. is a limiting factor in the CSPPS even at 60 °C and using the conventional or microwave heating; therefore, it should be further studied.
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Determinação de Cu e Fe em Biodiesel por Espectrometria de Absorção Atômica com Atomização Eletrotérmica e Estudo do Efeito Catalítico destes Metais sobre a Estabilidade Oxidativa do Biodiesel / Determination of Cu and Fe in Biodiesel by Absorption Spectrometry Electrothermal atomic and Study of the Effect of Catalytic Metals on the Oxidative Stability of Biodiesel

Ghisi, Mirela 16 May 2011 (has links)
Made available in DSpace on 2016-08-19T12:56:36Z (GMT). No. of bitstreams: 1 MIRELA GHISI.pdf: 1324849 bytes, checksum: 5d9ca5c5a49c366f3bf4959e2e942a14 (MD5) Previous issue date: 2011-05-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The metals content in biodiesel is directly related with the raw material used and also with the utilized biodiesel production method. In this work, an evaluation of the main metals present in biodiesel samples from different sources was done. The qualitative analysis of the metal content was assessed using the Inductively Coupled Plasma Mass Spectrometry technique after sample digestion in microwave oven. The main metals identified in the analyzed biodiesel samples were Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn. Metals like Ag, As, Ba, Cd, Co, Tl and V have not significant presence in the samples. Among these, Cu and Fe were selected due to their relevance and importance in oxidative process of biodiesel, to the development of an analytical methodology to be used in the determination by Electrothermal Atomic Absorption Spectrometry, and also evaluate the effect of these metals over the oxidative stability of the soy biodiesel. The samples were prepared with tetramethylammonium hydroxide (TMAH), and the pyrolysis and atomization temperatures were optimized pyrolysis and atomization curves. The high pyrolysis temperature adopted, 1000 oC, certainly minimized potential interferences, but calibration had to be carried out with aqueous standard solutions in the presence of the TMAH. The detection limits in the sample (3s, n=10), were quite low 15 ng g-1 and 24 ng g-1 for Cu and Fe, respectively. Seven biodiesel samples, produced from different raw materials, including vegetable seed, waste frying oil and animal fat were analyzed. Accuracy was validated by applying the recovery test (recoveries from 105% to 120%) and through comparison with the obtained results by High Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry. The precision, expressed by the relative standard deviation, was better than 3% for Cu and than 7% for Fe. Copper could be quantified in two and Fe in three of the seven samples. The biodiesel sample from fodder turnip was especially rich in the analytes in comparison to the other samples. The influence of metals Cu and Fe on soy biodiesel oxidative stability was evaluated by Rancimat method through induction period, according with the Standard EN 14112. The metals Cu2+ and Fe3+ were added to the biodiesel samples in the form of theirs salts, and different storage times of the samples were evaluated. Due to the catalytic behaviour of these metals, the oxidative stability of the samples was affected, even under low metal concentrations. Compared to Cu2+, the effect over the biodiesel stability was higher when Fe3+ was added. / A presença de metais no biodiesel está diretamente relacionada com a matéria-prima utilizada e também com o processo utilizado para a obtenção do biodiesel. Neste trabalho realizou-se uma avaliação dos principais metais presentes em amostras de biodiesel provenientes de diferentes fontes. A análise semi-quantitativa nas amostras de biodiesel foi realizada utilizando a técnica de Espectrometria de Massa com Plasma Indutivamente Acoplado após a digestão das amostras em micro-ondas. Os principais metais identificados nas amostras de biodiesel analisadas são Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr e Zn. Metais como Ag, As, Ba, Cd, Co, Tl e V não estão presentes em concentrações significativas nessas amostras. Em função de sua relevância e importância em processos oxidativos do biodiesel, selecionou-se Cu e Fe para o desenvolvimento de uma metodologia analítica para a determinação destes por Espectrometria de Absorção Atômica com Atomização Eletrotérmica e também a avaliação do efeito destes metais sobre a estabilidade oxidativa do biodiesel de soja. As amostras foram preparadas com hidróxido de tetrametilamônio (TMAH), e as temperaturas de pirólise e atomização foram otimizadas através de curvas de pirólise e atomização. A alta temperatura de pirólise adotada, 1000 oC, certamente ajudou a minimizar possíveis interferências; porém, a calibração teve de ser realizada com padrões aquosos na presença de TMAH. Os limites de detecção (3s, n = 10), na amostra, foram baixos, 15 ng g-1 e 24 ng g-1 para Cu e Fe, respectivamente. Sete amostras de biodiesel, produzidas de diferentes matérias-primas, incluindo óleos vegetais, óleo de fritura e gordura animal foram analisadas. A exatidão foi avaliada através do teste de recuperação (recuperações de 105% a 120%) e através da comparação com os resultados obtidos por Espectrometria de Absorção Atômica de Alta Resolução com Fonte Contínua e Atomização Eletrotérmica. A precisão, expressa pelo desvio padrão relativo foi melhor que 3% para Cu e que 7% para Fe. Cobre pôde ser quantificado em duas e Fe em três das sete amostras. A amostra de biodiesel proveniente do nabo forrageiro era especialmente rica nos analitos comparada às outras amostras. A influência dos metais Cu e Fe sobre a estabilidade oxidativa do biodiesel de soja foi avaliada pelo método Rancimat através do período de indução, de acordo com a Norma EN 14112. Os metais Cu2+ e Fe3+ foram adicionados nas amostras de biodiesel na forma de seus sais, e foram avaliados diferentes tempos de armazenamento das amostras. Devido ao efeito catalítico destes metais, a estabilidade oxidativa das amostras analisadas foi reduzida mesmo na presença de baixas concentrações dos metais. O efeito do Fe3+ sobre a estabilidade do biodiesel foi significativamente maior quando comparado ao Cu2+.
88

"Avaliação da alteração dimensional da base de prova permanente da prótese total de resina acrílica ativada termicamente, processada em forno microondas, por meio da imagem digital" / Evaluation of the dimensional alteration according to the permanent proof base for complete denture made of thermally activated acrylic resin, in microwave process, using digital image

Ana Paula Barbosa de Lima 11 August 2006 (has links)
Foram confeccionados 50 corpos de prova, divididos em 30 próteses totais superiores e 20 bases de provas permanentes, padronizados, para se avaliar a alteração dimensional da base de prova permanente, com dupla polimerização, processada em forno de microondas convencional; base de prova permanente com dupla polimerização, processada no método convencional; e a prótese total em uma única polimerização. Para essa análise, essas próteses foram divididas em 5 grupos: grupo I – prótese total convencional – banho de água (controle); grupo II – base de prova permanente processada convencionalmente; grupo III – base de prova permanente processada em forno de microondas convencional; grupo IV – prótese total superior padronizada com base de prova permanente processada convencionalmente, com as bases do grupo II; grupo V – prótese total superior com base de prova permanente, processada no forno de microondas convencional, com as bases de prova do grupo III. Para avaliar essa alteração foi usado o recurso do scaneamento da região posterior das próteses, “Post-dam”, desses corpos de prova. Após esse processo, a imagem capturada foi levada para o programa Photoshop 8.0 determinando a região de avaliação. Após essa seleção, a imagem é acessada no CorelTrace 11 para ser transformada em preto e branco e vetorizada, sendo, então, levada para o CorelDraw 11 para ser feita a medição do espaço da região posterior, entre o modelo e a base de prova/prótese total, para permitir a análise dos valores da alteração dimensional dos corpos de prova em questão, após o processamento. Os resultados mostram que: 1) a diferença da variação média para os lados esquerdo, centro e direito, respectivamente, na ordem de décimos ou centésimos de milímetros, para o grupo IV e I (0,07; 0,08 e 0,09); para o grupo V e I (0,10; 0,32 e 0,25) e para o grupo V e IV (0,17; 0,24 e 0,16) não pode ser considerada relevante clinicamente para afetar o ajuste da prótese na boca e promover a ocorrência de maiores transtornos clínicos; 2) A alteração média das áreas do lado esquerdo e direito para o grupo I, II e IV obtiveram uma homogeneidade na alteração, diferindo os Grupos III e V em relação aos outros, não existindo porém, diferença significante a nível de 5% entre as áreas desses segmentos; 3) A análise da variância do índice da área dos cinco (5) grupos não apresentou resultado significante que desabonasse a utilização de qualquer um dos métodos para a confecção da prótese total. No entanto, mais estudos devem ser realizados com o intuito de se aprimorar o uso do forno de microondas para o processamentos da prótese. / The 50 samples of pattern maxillary complete denture were processed, divided in 30 maxillary complete denture and 20 permanent proof base, to evaluated of dimensional changes in the permanent proof base with twice polymerization, process in microwave oven, to compare with the others two groups, the complete denture with conventional process and the complete denture with permanent proof base with twice polymerization in a conventional process. To evaluated this complete dentures they were divided in 5 groups: group I – conventional complete denture; group II – proof base conventional process; group III – proof base in microwave process; group IV – complete denture using the proof base of the group, with the conventional process and the group; group V – complete denture using the proof base of the group III, microwave process. To evaluated this alteration used the scanner in the “Post-dam”, in this samples. After this proceding the image was putting in the Adobe Photoshop 8.0 program to determinate what region was evaluated. After this selection, the image access in the CorelTrace 11 program and transformed in black and white, and after to access in the CorelDraw 11 that was measured the region between the cast and the complete/permanent proof base, to allow the analysis of the values the dimensional alteration of the proof body, after the process. The results show: 1) The linear dimensional alteration the difference mean variation for the left, center and right sides, respectively, it was in decimal order or centesimal of millimeters, for the group IV and I (0,07; 0,08 and 0,09); and for the group V and I were (0,10; 0,32 and 0,25) and for the group V and IV (0,17; 0,24 and 0,16) and it cannot be considered clinically relevant to affect the prosthesis adjustment in the mouth, and promote the occurrence of more clinical disruptions; 2) The dimensional alterations in the areas (left and right side) of the proof bodies of the three groups I, II and IV were uniform, and the groups III and V weren’t homogeneous, but there is not a statically significant difference, about 5%, between the segment left and right areas; 3) The variation of the area index about five groups there is not a statically significant that couldn’t use of the both method to build the complete denture. Although, more studies are important to realize with the objective to improve the use the microwave over to process the denture.
89

Método de estufa para determinação do grau de umidade de sementes de arroz e soja / The oven drying method for determination of the moisture content of rice and soybean seeds

Lopes, Madelon Schimmelpfennig 05 June 2008 (has links)
Made available in DSpace on 2014-08-20T13:44:32Z (GMT). No. of bitstreams: 1 tese_madelon_lopes.pdf: 412041 bytes, checksum: 7cffdcc13d1d613161f3352ea9700569 (MD5) Previous issue date: 2008-06-05 / The aim of this work was to a) compare the standard official methodology in Brazil for the determination of the moisture content of rice and soybean seeds (i.e. oven dried at 105°C for 24 hours) to the ISTA standard method (103°C for 17 hours), and b) test the possibility to determine whether the moisture content (MC) of rice and soybean seeds can be accurately estimated drying for a period shorter than 24h. Previously, a study was performed to establish the influence of the sample position within the oven, aimed to reduce the variation of the results on MC among different seed samples. The rice and soybean seeds tested in the experiment showed MC as determined by oven drying at 105°C/24h of 9.0%; 17.6% and 7.5%; 16.8%, respectively. The MC of whole rice and soybean seeds was estimated through oven drying at temperatures of 70, 103, 105 e 130°C for periods of 1, 3, 5, 7, 17, 24, 48, 72 and 96 hours for each level of temperature. Following ISTA standards, ground seeds were employed to determine their MC through the standard procedure (oven dried at 103°C/17h), whereas for the alternative procedure rice seeds were oven dried at 130°C for two hours. It was concluded that drying at 105°C/24h either underestimate the MC of rice and soybean seeds, when the MC was under 10% and overestimate when was equal or superior of 17,6%. It is possible to estimate its value in whole soybean seeds by drying them at 130°C for less than 24h depending of the seeds MC. / O presente trabalho teve como objetivos: a) comparar o método oficial de determinação do grau de umidade de sementes de arroz e soja utilizados no Brasil (Estufa a 105°C/24 horas) com o método de referência Estufa a 103°C/17 horas, adotado pela ISTA, e b) verificar a possibilidade de determinação do grau de umidade das sementes de arroz e soja em tempo inferior a 24 horas. Estudo prévio foi realizado para verificar a influência da posição da amostra na estufa com a finalidade de reduzir a variação na determinação do grau de umidade das sementes analisadas. Foram utilizadas sementes de arroz e de soja, com graus de umidade obtidos pelo método de Estufa a 105°C/24 horas de 9,0%; 17,6% e 7,5%;16,8%, respectivamente. Foram determinados os graus de umidade das sementes inteiras de arroz e soja, em estufa do tipo mecânico de ar forçado, submetidas às temperaturas de 70, 103, 105 e 130°C por um período de 1, 3, 5, 7, 17, 24, 48, 72 e 96 horas, para cada uma das temperaturas utilizadas. Foram utilizadas sementes moídas, segundo critérios da ISTA, para a determinação do teor de água pelo método de referência (Estufa a 103°C/17 horas), e para a determinação do grau de umidade pelo método alternativo para sementes de arroz Estufa a 130°C por 2 horas. O método de Estufa a 105ºC/24h subestima o teor de água das sementes de arroz e soja com grau de umidade inferior a 10% e superestima o teor de água das sementes quando for igual ou superior a 17,6%. É possível determinar o teor de água das sementes de soja em tempo inferior a 24 horas, utilizando sementes inteiras e temperatura de 130ºC, dependendo do teor de água das sementes.
90

Le four de Sévrier en Haute-Savoie à l’âge du Bronze : Reprise des données et nouvelles perspectives / The Sévrier kiln (Haute-Savoie, France) in the Bronze Age : Data recovery and new perspectives

Coulon, Jean 24 October 2012 (has links)
Découvert dans les années 1970 sur le site palafitte aujourd’hui immergé du Crêt de Châtillon (lac d’Annecy, Haute-Savoie, France), le four de Sévrier, daté de l’âge du Bronze, est considéré comme un des plus anciens fours de potier d’Europe occidentale. Il incarne l’arrivée d’une nouvelle technologie qui marquera la disparition progressive des modes de cuisson en fosse ou en meule en usage depuis l’invention de la poterie. En cette fin de l’âge du Bronze l’acmé de l’art céramique, représenté par les productions de poteries fines, pouvait donc être lié à l’utilisation d’un tel dispositif. Le caractère unique de cette construction en argile, de dimensions modestes et à parois étonnamment minces, réside dans sa conception modulaire et portable. La découverte publiée en 1975 (Bocquet et Couren 1975) recueille aussitôt un échoeuropéen et près de quarante ans après, elle reste pratiquement sans équivalent. L’utilisation de fours de potier à l’âge du Bronze, dans un contexte occidental, demeure pourtant une question ouverte et depuis les années 80, l’interprétation avancée pour le four de Sévrier alimente régulièrement ce débat. L’objectif de cette thèse de doctorat est de porter un nouveau regard sur cet objet de référence quelque peu voilé par sa célébrité et réexaminer les hypothèses fonctionnelles non encore étudiées. Après une présentation du contexte et de l’historique de la découverte, un premier volet aborde différents aspects de l’objet archéologique: sa morphologie, sa conception, sa restauration, son comportement lors d’expérimentations de cuissons de céramiques, ses traits singuliers qui le rapprochent ou le distinguent des fours de potiers plus tardifs ou des structures d’argile à parois fines diversement interprétées. Notre analyse du four de Sévrier comporte trois volets : a) l’inventaire du matériel découvert sur le Crêt de Châtillon et l’intégration éventuelle d’éléments non pris en compte dans la reconstruction, b) une analyse archéométrique (minéralogie des argiles) portant sur les tessons du four et sur des argiles des gisements situés à proximité du Crêt de Châtillon. Une analyse des changements de phases des argiles cuites en fonction de l’intensité de la température, c) l’évaluation de la température minimale et maximale subie par le four afin de confirmer ou exclure certaines utilisations. L’analyse fonctionnelle du four aborde, en premier lieu, l’hypothèse privilégiée, celle consacrée à la cuisson des poteries. Une méthode expérimentale comparative permet de préciser les avantages et inconvénients de différents procédés de cuisson de poteries noires et cherche à évaluer l’apport technologique supposé avoir été introduit par le four de Sévrier. D’autres alternatives sont abordées, en particulier la fonction culinaire. Cette interprétation est confortée par la découverte d’inédits indices d’usages observés lors de cette étude sur des matériels similaires de même époque et provenance. L’inventaire des structures comparables constitue un autre volet de cette recherche. Elle témoigne de l’usage courant des structures de cuisson en argile de faible épaisseur aux âges du Bronze et du Fer. Leur diffusion géographique s’étend des Balkans à l’Espagne et de la Grande Bretagne à la Grèce. Le recensement d’une famille large et multiforme de dispositifs portables en argile à vocation domestique nous permet de poser les bases d’une typologie et de proposer un scénario d’évolution et d’influences entre des régions parfois très éloignées. / This study focuses on a unique archaeological finding from the Crêt de Châtillon, a late Bronze Age lacustrine village situated on a now submerged island in Lake Annecy (Haute-Savoie, France). The Sévrier kiln is considered to be one of the oldest pottery kiln in Western Europe. Over the years it has become internationally known and still forms the basis of research projects and experiments relating to Bronze Age ceramic technology. It embodies the arrival of a new technology that would mark the gradual disappearance of the open fire or pit firing modes that had been used since the invention of pottery. As such, the acme of ceramic art which marks the end of the Bronze Age, may therefore be related to the use of such a device. The uniqueness of this clay building of modest proportions and surprisingly thin walls, lies in it modular and portable design. The discovery, published in 1975 (Bocquet and Couren 1975) soon received a valuable feedback in Europe and nearly forty years later remains virtually unparalleled. However, the use of pottery kilns in the Bronze Age in a Western context remains an open question. Since the 1980s, several arguments will gradually undermine this interpretation. The purpose of this study is to take a fresh look at this inescapable object, somewhat veiled by its celebrity and review functional hypotheses hitherto not studied. After describing the background and the history of the discovery, we discuss various aspects of the archaeological kiln: morphology, design, restoration, use, experimentations and singular features that approximate or distinguish this furnace from later pottery kilns or thin-walled clay structures wich have been variously interpreted. This analysis of the kiln of Sévrier has been threefolds: (a) an inventory of the findings from the Crêt de Châtillon and a discussion about the integration of many components excluded from the reconstruction ; (b) archaeometric analysis (clay mineralogy) of the kiln and the clay deposits located near the site and (c) identification of the changing phases in clays, subjected to high temperatures and determination of the temperature experienced by the furnace. The functional analysis, reviews different hypotheses : (a) pottery firing : a comparative experimental method that aims to highlight the benefits and disadvantages of different processes to produce black pottery. The purpose is to underscore the technological contribution assumed to have been introduced by the Sévrier kiln. (b) Other functional alternatives will be discussed, especially the culinary function. This interpretation is supported by the discovery of unprecedented indices discovered during this study. The inventory of comparable structures is another aspect of this research. The relatively widespread use of such thin-walled clay structures during the Bronze and Iron ages is highlighted. Their geographical distribution extends from the Balkans to Spain and from Great Britain to Greece. The census of a multiform family of domestic portable clay ovens allows us to propose a new typology and a scenario of diffusion between regions sometimes very remote, completes this new outlook and draw new perspectives for the research.

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