958 resultados para NUCLEAR REACTORS


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The main purpose of this work is to describe the use of the technique Site-Specific Natural Isotopic Fractionation of hydrogen (SNIF-NMR), using ²H and ¹H NMR spectroscopy, to investigate the biosynthetic origin of acetic acid in commercial samples of Brazilian vinegar. This method is based on the deuterium to hydrogen ratio at a specific position (methyl group) of acetic acid obtained by fermentation, through different biosynthetic mechanisms, which result in different isotopic ratios. We measured the isotopic ratio of vinegars obtained through C3, C4, and CAM biosynthetic mechanisms, blends of C3 and C4 (agrins) and synthetic acetic acid.

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Coffee is one of the beverages most widely consumed in the world and the "cafezinho" is normally prepared from a blend of roasted powder of two species, Coffea arabica and Coffea canephora. Each one exhibits differences in their taste and in the chemical composition, especially in the caffeine percentage. There are several procedures proposed in the literature for caffeine determination in different samples like soft drinks, coffee, medicines, etc but most of them need a sample workup which involves at least one step of purification. This work describes the quantitative analysis of caffeine using ¹H NMR and the identification of the major components in commercial coffee samples using 1D and 2D NMR techniques without any sample pre-treatment.

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During the last five decades, as a result of an interaction between natural product chemistry, synthetic organic chemistry, molecular biology and spectroscopy, scientists reached an extraordinary level of comprehension about the natural processes by which living organisms build up complex molecules. In this context, 13C nuclear magnetic resonance spectroscopy, allied with isotopic labeling, played a determinant role. Nowadays, the widespread use of modern NMR techniques allows an even more detailed picture of the biochemical steps by accurate manipulation of the atomic nuclei. This article focuses on the development of such techniques and their impact on biosynthetic studies.

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The relationship between the magnetic dipole-dipole potential energy function and its quantum analogue is presented in this work. It is assumed the reader is familiar with the classical expression of the dipolar interaction and has basic knowledge of the quantum mechanics of angular momentum. Except for these two points only elementary steps are involved.

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Glass ionomer cements (GICs) are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid) in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental and to investigate the structural changes during hardening of the cements by FTIR and Al MAS NMR. These analyses showed that the experimental glass powder reacted with organic acid to form the GICs and it is a promising material to manufacture dental cements.

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In this work, ¹H Nuclear Magnetic Resonance (¹H NMR) was employed to evaluate changes in apple juice in response to the addition of Panzym® Yieldmash and Ultrazym® AFP-L enzymatic complexes and compare it with premium apple juice. The juice was processed at different temperatures and concentrations of enzymatic complexes. The differences in the results were attributed mainly to the enzyme concentrations, since temperature did not cause any variation. A quantitative analysis indicated that the concentration of fructose increased while the concentrations of sucrose and glucose decreased in response to increasing concentrations of the enzymatic complexes.

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Nuclear magnetic resonance is a technique that is widely used for elucidating and characterizing organic substances. Organofluorine substances have applications in many areas from drugs to liquid crystals, but their NMR spectra are often challenging due to fluoride coupling with other nuclei. For this reason, NMR spectra of this class of substances are not commonly covered in undergraduate and graduate chemistry courses and related fields. Thus, the aim of this work was the presentation and discussion of 1H, 13C, and 19F NMR spectra of eleven organofluorine substances which, in the case of 1H and 13C nuclei, showed classic patterns of first-order coupling and the effects of the fluorine nucleus in different chemical and magnetic environments. In addition, the observation of long distance coupling constants was possible through the use of apodization functions in the processing of the spectra. It is expected that the examples presented herein can be utilized and discussed in undergraduate and graduate NMR spectroscopy disciplines and thus improve the teaching and future research of organofluorine compounds.

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Diplomityössä selvitettiin Fortum Power and Heat Oy:n Loviisan VVER-440 painevesireaktorilaitosten termisen tehon laskentaan liittyviä epävarmuuksia. Laitoksen turvallisuusteknisissä käyttöehdoissa (TTKE) määrätään reaktorin suurimmaksi sallituksi lämpötehoksi 1500 MW. Tähän perustuen haluttiin selvittää nykyiseen RT1 laskentaan liittyvät epävarmuudet tarkastamalla nykyinen laskenta ja siinä käytetyt termohydrauliset laskentasovitteet. Työn alussa selostetaan lyhyesti Loviisan voimalaitoksen toimintaperiaate, jonka jälkeen esitellään laskentaan osallistuvat prosessimittaukset ja niihin liittyvät epävarmuustekijät. Mittauksille määritettiin epävarmuudet käyttäen hyödyksi komponenttivalmistajien tietoja sekä laitoksen kalibrointitodistuksia ja näiden lisäksi laskettiin standardin mukainen virhe virtauslaipoille. Edellä mainittujen virheiden perusteella voitiin laskea tehon epävarmuudet yksittäiselle höyrystimelle, josta edelleen varianssien summamenetelmällä saatiin reaktorin termiselle teholle 0,78 %:n epävarmuus 95 % luottamustasolla. Laskettua tehon epävarmuutta verrattiin Monte Carlo -menetelmällä suoritettuun tarkistuslaskentaan, jolla termisen tehon epävarmuudeksi saatiin 0,53 %, luottamustason ollessa 95 %. Työssä tarkasteltiin keskiarvotuksen vaikutusta mittausdataan. Näissä tarkasteluissa havaittiin pinnansäädöstä aiheutuva reaktoritehon huojunta, joka oli työn merkittävin havainto.

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Paper presented in ISA RC23 meeting, Gothenburg July 16th 2010

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The results shown in this thesis are based on selected publications of the 2000s decade. The work was carried out in several national and EC funded public research projects and in close cooperation with industrial partners. The main objective of the thesis was to study and quantify the most important phenomena of circulating fluidized bed combustors by developing and applying proper experimental and modelling methods using laboratory scale equipments. An understanding of the phenomena plays an essential role in the development of combustion and emission performance, and the availability and controls of CFB boilers. Experimental procedures to study fuel combustion behaviour under CFB conditions are presented in the thesis. Steady state and dynamic measurements under well controlled conditions were carried out to produce the data needed for the development of high efficiency, utility scale CFB technology. The importance of combustion control and furnace dynamics is emphasized when CFB boilers are scaled up with a once through steam cycle. Qualitative information on fuel combustion characteristics was obtained directly by comparing flue gas oxygen responses during the impulse change experiments with fuel feed. A one-dimensional, time dependent model was developed to analyse the measurement data Emission formation was studied combined with fuel combustion behaviour. Correlations were developed for NO, N2O, CO and char loading, as a function of temperature and oxygen concentration in the bed area. An online method to characterize char loading under CFB conditions was developed and validated with the pilot scale CFB tests. Finally, a new method to control air and fuel feeds in CFB combustion was introduced. The method is based on models and an analysis of the fluctuation of the flue gas oxygen concentration. The effect of high oxygen concentrations on fuel combustion behaviour was also studied to evaluate the potential of CFB boilers to apply oxygenfiring technology to CCS. In future studies, it will be necessary to go through the whole scale up chain from laboratory phenomena devices through pilot scale test rigs to large scale, commercial boilers in order to validate the applicability and scalability of the, results. This thesis shows the chain between the laboratory scale phenomena test rig (bench scale) and the CFB process test rig (pilot). CFB technology has been scaled up successfully from an industrial scale to a utility scale during the last decade. The work shown in the thesis, for its part, has supported the development by producing new detailed information on combustion under CFB conditions.

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Tässä kirjallisuustyössä tutustutaan kolmeen kaupallisissa painevesilaitoksissa käytettyyn höyrystinkonstruktioon: U-putkipystyhöyrystimeen, U-putkivaakahöyrystimeen ja läpivirtaushöyrystimeen. Työssä tutustutaan näiden ratkaisujen erityispiirteisiin ja vertaillaan niitä keskenään.

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RESUMO Este ensaio destaca a importância das competências de comunicação clínica (CCC) nas ciências da saúde. Estas competências podem ser ensinadas, aprendidas e avaliadas, e vários estudos evidenciam para as vantagens de uma formação específica nesta área, potenciando a relação que os profissionais da área da saúde estabelecem com os pacientes, cuidadores informais e equipas de saúde, com resultados melhorados nos indicadores de saúde e cuidados mais humanizados. Confrontados com dificuldades na integração de programas específicos de comunicação nos curricula, assim como um défice no processo de avaliação e feedback estruturado, é crucial um investimento na formação pedagógica e no desenvolvimento curricular. Conscientes da escassez de trabalhos sistemáticos que apontam para um consenso sobre as competências e objetivos de ensino-aprendizagem das CCC, o sub-grupo Core Curriculum do comité de ensino (tEACH) da Associação Europeia de Comunicação em Saúde (EACH) desenvolveu e alcançou um consenso para um currículo nuclear nas diferentes áreas da saúde. Neste contexto, surgiu o Health Professions Core Communication Curriculum – HPCCC, que pode servir como referencial flexível de acordo com as necessidades específicas e contribuir para uma maior sistematização das iniciativas de CCC em saúde em língua portuguesa.

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The nucleus is a membrane enclosed organelle containing most of the genetic information of the cell in the form of chromatin. The nucleus, which can be divided into many sub-organelles such as the nucleoli, the Cajal bodies and the nuclear lamina, is the site for several essential cellular functions such as the DNA replication and its regulation and most of the RNA synthesis and processing. The nucleus is often affected in disease: the size and the shape of the nucleus, the chromatin distribution and the size of the nucleoli have remained the basis for the grading of several cancers. The maintenance of the vertebrate body shape depends on the skeleton. Similarly, in a smaller context, the shape of the cell and the nucleus are mainly regulated by the cytoskeletal and nucleoskeletal elements. The nuclear matrix, which by definition is a detergent, DNase and salt resistant proteinaceous nuclear structure, has been suggested to form the nucleoskeleton responsible for the nuclear integrity. Nuclear mitotic apparatus protein, NuMA, a component of the nuclear matrix, is better known for its mitotic spindle organizing function. NuMA is one of the nuclear matrix proteins suggested to participate in the maintenance of the nuclear integrity during interphase but its interphase function has not been solved to date. This thesis study concentrated on the role of NuMA and the nuclear matrix as structural and functional components of the interphase nucleus. The first two studies clarified the essential role of caspase-3 in the disintegration of the nuclear structures during apoptosis. The second study also showed NuMA and chromatin to co-elute from cells in significant amounts and the apoptotic cleavage of NuMA was clarified to have an important role in the dissociation of NuMA from the chromatin. The third study concentrated on the interphase function of NuMA showing NuMA depletion to result in cell cycle arrest and the cytoplasmic relocalization of NuMA interaction partner GAS41. We suggest that the relocalization of the transcription factor GAS41 may mediate the cell cycle arrest. Thus, this study has given new aspects in the interactions of NuMA, chromatin and the nuclear matrix.

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Kandidaatintutkielmassa esitellään kolmannen sukupolven painevesireaktorilaitosten passiivisia turvallisuusjärjestelmiä.

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Diplomityön tarkoituksena oli tutkia vaatimusten hallintaa suunnittelu- ja konsultointiyrityksen kannalta Suomen ydinvoimaprojekteissa keskittyen ydinturvallisuus- ja laatuvaatimuksiin. Ydinvoimaprojekteissa toimiminen on edellyttänyt menettelyohjeiden ja laatujärjestelmän uudelleen organisointia yrityksessä ja esiin on noussut haasteita liittyen muun muassa vaatimusten tunnistamiseen ja todentamiseen erityyppisissä ja erilaajuisissa projekteissa. Työ toteutettiin perehtymällä ydinvoimaan liittyvään lainsäädäntöön Suomessa, ohjeisiin ja standardeihin sekä haastattelemalla yrityksen omia asiantuntijoita. Viimeaikaisista sekä meneillään olevista projekteista kerättiin kokemuksia sekä arvioitiin ydinvoima projekteja varten laaditun projektin toteutusohjeen toimivuutta ja käytettävyyttä esimerkkiprojektin avulla. Suurimmiksi haasteiksi tunnistettiin lainsäädännöllisten vaatimusten, kuten ydinvoima- laitosohjeiden (YVL) muuttuminen ja tulkinnanvaraisuus sekä asiakkaiden perehtymät- tömyys Suomen lainsäädäntöön ja vaatimustasoon liittyen ydinturvallisuuteen. Työn tuloksena tunnistettiin hyviä vaatimusten hallintaan liittyviä projektinhallintaa ja ydin- turvallisuutta edistäviä asioita, kuten vaatimusten täsmentäminen jo sopimustasolla sekä niiden täyttymisen seuranta projektin aikana. Erillisen vaatimustietokannan luomista ydinvoimaprojekteja varten tutkittiin, mutta siitä luovuttiin teknisten vaatimusten osalta kannattamattomana, sillä standardien ja vaatimusten määrä kasvoi niin suureksi, että niiden hallitseminen vaatisi enemmän työtä kuin mitä projektien taso yleensä sallisi.