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Medidas de seccoes de choque medias no espectro de fissao do U-235 para algumas reacoes de limiarMAIDANA, NORA L. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:37:13Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:04Z (GMT). No. of bitstreams: 1
04784.pdf: 1414862 bytes, checksum: dd92e9abc5bb1044dcef6e7b745b4846 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Desenvolvimento de método de recuperação de 131I no processo de produção de 99Mo pela fissão de 235U / Development of a recovery method of 131I in the 99Mo process through the fission of 235UBignardi, Aline Moraes Teixeira 24 June 2013 (has links)
O 131I é um radioisótopo de iodo amplamente utilizado em medicina nuclear, pode ser utilizado tanto para diagnóstico quanto para tratamento devido às suas características físicas de decaimento - e sua elevada emissão de raios-y. Sua produção no IPEN é realizada utilizando um reator nuclear a partir da reação indireta: 130Te (n,y) 131mTe 131Te 131I, onde são irradiados alvos contendo Te. Pode também ser produzido via produto de fissão de 235U, onde, o 235U irradiado produz cerca de 300 elementos diferentes, entre eles o 131I. O 131I produzido nesse método apresenta altas atividade específica e concentração radioativa, o que facilita a produção de compostos marcados com o radionuclídeo. O objetivo deste trabalho é desenvolver um método de recuperação de 131I no processo de produção de 99Mo pela rota de dissolução ácida de alvos de 235U, com a qualidade necessária para ser utilizado em Medicina Nuclear. O 131I encontra-se em 2 fases no processo, tanto na fase gasosa produzida na dissolução ácida dos alvos de U metálico e a menor parte em solução. Foram utilizados diversos materiais para captura e recuperação de 131I nas 2 fases do processo, a fase gasosa e a solução de dissolução dos alvos de U. Foram testadas colunas de alumina com Cu, alumina ácida com Cu, nanoesferas de Ag, cartuchos aniônicos, resina aniônica, colunas de carvão ativado, microesferas de Ag e microesferas de Cu. Soluções contendo 131I em NaOH 0,1 mol.L-1 foram percoladas pelos materiais e os eluídos foram analisados em calibrador de dose. Foi também estudada a precipitação de AgI e dissolução desse precipitado em NH4OH 0,1 mol L-1 e Na2S2O3 5%. Dentre os testes realizados, a princípio, os resultados de recuperação variaram de acordo com o material, o carvão ativado apresentou rendimento de recuperação entre 42% a 83%. Já o rendimento de recuperação da coluna de alumina com Cu variou de 20% a 85%. Os testes com nanoesferas de Ag apresentaram rendimento de recuperação de 26% utilizando NaOH 0,1 mol L-1 e 72% utilizando Na2S2O3 como eluentes. Testes com cartuchos aniônicos apresentaram os melhores resultados com uma porcentagem de recuperação de 81 a 90%. Testes utilizando 131I na sua forma gasosa apresentaram uma retenção de 66,45% e não foram realizados testes para recuperação do 131I retido. Nos testes utilizando precipitação de AgI a porcentagem de retenção de 131I foi de 100%. É possível concluir que os cartuchos aniônicos e a precipitação de AgI foram as melhores opções para a retenção de 131I, e as colunas de alumina com Cu tem um grande potencial para eluição do radionuclídeo 131I na forma química adequada. / 131I is an iodine radioisotope widely used in nuclear medicine that can be used either for diagnostic or for treatment due to its physical decay by - and its high emission of -rays. It is produced at IPEN using the indirect reaction: 130Te(n,)131mTe 131Te 131I where TeO2 targets are irradiated in a Nuclear Reactor. There is also the possibility of producing 131I by the fission of 235U, where about 300 different elements are produced together with 131I. The 131I produced through this method presents high specific activity and radioactive concentration suitable for the labeling of molecules. The aim of this work was to develop a recovery method of 131I with the required quality to be used in Nuclear Medicine in the 99Mo production process through the route of acid dissolution of metallic 235U targets. 131I can appear in two phases of the process, both in the gaseous phase produced during the dissolution of metallic U targets and in the dissolution solution. This work studied the recovery of 131I in these two phases. Several materials were used for the capture and recovery of 131I at the two phases of the process, the gaseous one and the solution of dissolution of U targets. Columns of alumina with Cu, acid alumina with Cu, Ag microspheres, Cu microspheres, Ag nanospheres, anionic cartridges, Ag cartridges, anion exchange resin and activated charcoal columns were tested. Solutions containing 131I in 0.1 mol.L-1 NaOH were percolated through the materials and the eluted solutions were analyzed in a dose calibrator. The precipitation of AgI was also studied wth further dissolution of this precipitate with 0.1 mol L-1 NH4OH and 5% Na2S2O3. The recovery results varied according to the material, activated charcoal showed recovery yields between 42% and 83% but the recovery yield of the alumina column with Cu ranged from 20% to 85%. Tests with Ag nanospheres showed recovery yield of 26% using 0.1 mol L-1NaOH and 72% for Na2S2O3. Tests with anionic cartridges showed the best results with a recovery percentage ranging between 81 to 90%. Tests using 131I in the gaseous phase presented retention of 66.45% and its elution was not studied. The experiments with the AgI precipitation showed total retention of 131I. It can be concluded that the anionic cartridges and the precipitation of AgI have higher affinity for the retention of 131I, and alumina columns with Cu have great potential for its elution in a suitable chemical form.
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Desenvolvimento de método de recuperação de 131I no processo de produção de 99Mo pela fissão de 235U / Development of a recovery method of 131I in the 99Mo process through the fission of 235UAline Moraes Teixeira Bignardi 24 June 2013 (has links)
O 131I é um radioisótopo de iodo amplamente utilizado em medicina nuclear, pode ser utilizado tanto para diagnóstico quanto para tratamento devido às suas características físicas de decaimento - e sua elevada emissão de raios-y. Sua produção no IPEN é realizada utilizando um reator nuclear a partir da reação indireta: 130Te (n,y) 131mTe 131Te 131I, onde são irradiados alvos contendo Te. Pode também ser produzido via produto de fissão de 235U, onde, o 235U irradiado produz cerca de 300 elementos diferentes, entre eles o 131I. O 131I produzido nesse método apresenta altas atividade específica e concentração radioativa, o que facilita a produção de compostos marcados com o radionuclídeo. O objetivo deste trabalho é desenvolver um método de recuperação de 131I no processo de produção de 99Mo pela rota de dissolução ácida de alvos de 235U, com a qualidade necessária para ser utilizado em Medicina Nuclear. O 131I encontra-se em 2 fases no processo, tanto na fase gasosa produzida na dissolução ácida dos alvos de U metálico e a menor parte em solução. Foram utilizados diversos materiais para captura e recuperação de 131I nas 2 fases do processo, a fase gasosa e a solução de dissolução dos alvos de U. Foram testadas colunas de alumina com Cu, alumina ácida com Cu, nanoesferas de Ag, cartuchos aniônicos, resina aniônica, colunas de carvão ativado, microesferas de Ag e microesferas de Cu. Soluções contendo 131I em NaOH 0,1 mol.L-1 foram percoladas pelos materiais e os eluídos foram analisados em calibrador de dose. Foi também estudada a precipitação de AgI e dissolução desse precipitado em NH4OH 0,1 mol L-1 e Na2S2O3 5%. Dentre os testes realizados, a princípio, os resultados de recuperação variaram de acordo com o material, o carvão ativado apresentou rendimento de recuperação entre 42% a 83%. Já o rendimento de recuperação da coluna de alumina com Cu variou de 20% a 85%. Os testes com nanoesferas de Ag apresentaram rendimento de recuperação de 26% utilizando NaOH 0,1 mol L-1 e 72% utilizando Na2S2O3 como eluentes. Testes com cartuchos aniônicos apresentaram os melhores resultados com uma porcentagem de recuperação de 81 a 90%. Testes utilizando 131I na sua forma gasosa apresentaram uma retenção de 66,45% e não foram realizados testes para recuperação do 131I retido. Nos testes utilizando precipitação de AgI a porcentagem de retenção de 131I foi de 100%. É possível concluir que os cartuchos aniônicos e a precipitação de AgI foram as melhores opções para a retenção de 131I, e as colunas de alumina com Cu tem um grande potencial para eluição do radionuclídeo 131I na forma química adequada. / 131I is an iodine radioisotope widely used in nuclear medicine that can be used either for diagnostic or for treatment due to its physical decay by - and its high emission of -rays. It is produced at IPEN using the indirect reaction: 130Te(n,)131mTe 131Te 131I where TeO2 targets are irradiated in a Nuclear Reactor. There is also the possibility of producing 131I by the fission of 235U, where about 300 different elements are produced together with 131I. The 131I produced through this method presents high specific activity and radioactive concentration suitable for the labeling of molecules. The aim of this work was to develop a recovery method of 131I with the required quality to be used in Nuclear Medicine in the 99Mo production process through the route of acid dissolution of metallic 235U targets. 131I can appear in two phases of the process, both in the gaseous phase produced during the dissolution of metallic U targets and in the dissolution solution. This work studied the recovery of 131I in these two phases. Several materials were used for the capture and recovery of 131I at the two phases of the process, the gaseous one and the solution of dissolution of U targets. Columns of alumina with Cu, acid alumina with Cu, Ag microspheres, Cu microspheres, Ag nanospheres, anionic cartridges, Ag cartridges, anion exchange resin and activated charcoal columns were tested. Solutions containing 131I in 0.1 mol.L-1 NaOH were percolated through the materials and the eluted solutions were analyzed in a dose calibrator. The precipitation of AgI was also studied wth further dissolution of this precipitate with 0.1 mol L-1 NH4OH and 5% Na2S2O3. The recovery results varied according to the material, activated charcoal showed recovery yields between 42% and 83% but the recovery yield of the alumina column with Cu ranged from 20% to 85%. Tests with Ag nanospheres showed recovery yield of 26% using 0.1 mol L-1NaOH and 72% for Na2S2O3. Tests with anionic cartridges showed the best results with a recovery percentage ranging between 81 to 90%. Tests using 131I in the gaseous phase presented retention of 66.45% and its elution was not studied. The experiments with the AgI precipitation showed total retention of 131I. It can be concluded that the anionic cartridges and the precipitation of AgI have higher affinity for the retention of 131I, and alumina columns with Cu have great potential for its elution in a suitable chemical form.
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Cherubim and Seraphim in the Old TestamentCarlill, A. J. January 2013 (has links)
This thesis is the first modern joint study of biblical Cherubim and Seraphim. I begin by setting out the recent history of their interpretation, before taking each of the biblical texts in turn. Chapter 1 looks at the references to Cherubim in Ezekiel. I argue that the Cherubim in Ezek. 1-11 are based upon the two large Cherubim in the sanctuary in Jerusalem. I investigate the different traditions represented by LXX and MT versions of Ezek. 28 and identify a tradition which may account for the MT of this chapter. Chapter 2 covers the other descriptions of living Cherubim in the biblical texts in Gen. 3 and Ps. 18. I argue for a conscious link with the Jerusalem Temple in both texts but for their independence from each other. All the references to Cherubim in the Temple and the Tabernacle are looked at in Chapter 3, and I offer a radical re-imagining of the two large Cherubim in the Solomonic Temple and on the Kapporeth in the Mosaic Tabernacle. In Chapter 4 I question the validity of translating the Cherubim Formula as “enthroned upon the Cherubim”, and offer an alternative translation which makes reference to all the Cherubim mentioned in the text. In Chapter 5, looking at the references to saraph, I follow Joines and others in arguing for a serpentine form for the Seraphim, but argue that this identity was forgotten at an early stage of the textual transmission, and that they were then seen as part of Yhwh’s heavenly host. Finally, I argue that the role of Cherubim and Seraphim is similar, being primarily apotropaic, but that both are associated with theophany and, less frequently, with heavenly worship.
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Depictions of sainthood in the Latin saints' lives of twelfth-century EnglandHarris, Eilidh January 2014 (has links)
This thesis examines the depiction of saintly figures within the Latin vitae of twelfth-century England (1066–c.1215). It tests the extent to which these depictions are homogeneous and examines what factors may have shaped representations. Analysis focuses on vitae of twelfth-century saints, a sample of texts that have not previously been examined as a corpus in this way. By encompassing a range of different types of saint, authors and contexts, utilising this corpus allows a comparative examination of how different facets of sainthood could be expressed in hagiography. The textual analysis at the heart of this study aims to unpick individual texts' ideals of saintly behaviour. Whilst hagiographers functioned within a well-established genre, considering a wide range of saints' vitae allows scrutiny of the impact of context in shaping depictions. It will be argued that these portrayals of saintly figures demonstrate thematic harmony which is tempered by individuality and context to form recognisable and yet distinctive depictions of sainthood. The analysis is structured around four common hagiographical themes, each worthy of detailed examination: Outer Appearance, Sexuality and Chastity, Food and Fasting, and Death. Chapter 1 investigates how saintly figures are described in terms of physical appearance, deportment and demeanour, and clothing. Chapter 2 focuses upon sexuality, exploring the manifestations of chastity and virginity within the Lives and testing how this might vary from saint to saint and between the sexes. Chapter 3 examines food and food abstention, previously under-represented in secondary literature on twelfth-century hagiography and on male saints. The thesis ends with a consideration of death, a surprisingly understudied theme in Anglophone scholarship. By examining the process of dying and the moment of mortality, this chapter will fill an important analytical vacuum between lived sanctity and sanctity in death.
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The cult of St Thomas Cantilupe and the politics of remembranceFleming, Andrew January 2013 (has links)
The thesis aims to answer the following question: how did the relationships people had with Thomas Cantilupe, Bishop of Hereford between 1275 and 1282, shape the nature of his posthumous cult? The thesis rejects the idea that the veneration of saints in medieval England was politically neutral, or that their cults represented a stable, uncontentious means of resolving social discord. Instead, it posits that the invocation and memorialisation of Cantilupe was an intrinsically political act, and one that was available to ordinary people; these memories were formulated through their personal experiences of life in thirteenth century Hereford, and the people and institutions that populated it. These arguments are primarily based on evidence drawn from Cantilupe’s canonisation proceedings, particularly records and testimonies of his purported miracles. The first chapter discusses the historiography of saints’ cults in medieval Europe, and how their social function has typically been characterised, and outlines the principal sources for the thesis and how they will be used. The second chapter of this thesis takes the form of a brief biography of Cantilupe’s life and career, with a particular focus on how his actions might have affected the ways different people perceived him after his death. The third chapter enumerates the principal institutions and individuals that exercised power alongside Cantilupe in the diocese, and situates miracle recipients for whom we otherwise have little evidence within these contexts. Chapter four deals with the perspectives generated by Cantilupe’s interactions with the other lay and ecclesiastical authorities that constituted the structures of power in the diocese. Chapter five concerns the attitudes generated through direct experience of Cantilupe himself, or the way in which these attitudes were mediated by someone who did know him personally. Evidence that helps us to establish how ideas about Cantilupe were memorialised is discussed in chapter six.
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Developmentally Appropriate Practice And Parental Involvement In Preschools: Parent And Teacher PerspectivesDemircan, Hasibe Ozlen 01 June 2012 (has links) (PDF)
The purpose of the study was to investigate the relationships among preschool teachers&rsquo / and preschoolers&rsquo / parents&rsquo / developmentally appropriate practice (DAP) and developmentally inappropriate practice (DIP) beliefs in relation to parental involvement attitudes and perceived parental involvement barriers.
To reach to the purposes of the study, data were collected from 279 teachers and 589 parents via a demographic information questionnaire and two main data collection instruments. The demographic information questionnaire aimed to obtain information about the participant&rsquo / s gender, age and educational level. In order to collect information from teachers and parents regarding their beliefs about developmentally appropriate practice / Teachers&rsquo / Beliefs Scale (TBS) (Burts et al., 2000) and the parent adaptation of the scale, Parents&rsquo / Beliefs Scale (Yen, 2008) were used. To ascertain parents&rsquo / and teachers&rsquo / attitudes and the barriers on parental involvement, the School and Family Partnerships Questionnaire (Epstein & / Salinas, 1993) was used.
The investigation of the relationship between the teachers&rsquo / and parents&rsquo / DAP and DIP beliefs in relation to their parent involvement attitudes (PIA), parent involvement barriers (PIB) revealed significant results. The findings of the study revealed that both the teachers&rsquo / and parents&rsquo / PIA and PIB made significant contributions to their DAP and DIP beliefs.
As found in the current study, the interaction between the teachers and parents should be increased to help children develop in the most appropriate way. In order to increase this relationship, a detailed focus on the parental involvement paradigm should be undertaken.
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Šiurkštaus darbo pareigų pažeidimo samprata pagal DK 235 straipsnio 2 dalies 11 punktą ir jo taikymo praktika / The concept of a gross breach of work duties according to article 235 part 2 (11) of the labour code and its practical applicationPažėrienė, Danguolė 23 June 2014 (has links)
Šiurkštaus darbo pareigų pažeidimo institutas darbo teisėje atsirado neseniai- tai yra tik įsigaliojus naujam Darbo Kodeksui. Šio pažeidimo sąvoka bei nebaigtinio sąrašo šiurkštaus darbo pareigų pažeidimo sudėčių įtvirtinimas kelia nemažai problemų taikant teisės normas praktikoje. Darbo kodekse esanti šiurkštaus darbo pareigų pažeidimo sąvoka nėra aiški ir išsami , be to numatytų pažeidimų sąrašas tik pavyzdinis, įstatymo leidėjo pozicija įtvirtinti ir kitus nusižengimus, kuriais šiurkščiai pažeidžiama darbo tvarka sukelia įvairių vertinimo bei interpretavimo problemų.Darbo teisės doktrinoje bei praktikoje kyla nesutarimų, kas tie kiti Darbo kodekso 235 straipsnio 2 dalies 11 punkto minimi atvejai? Dėl šių priežasčių darbe pirmiausia, analizuojama šiurkštaus darbo pareigų pažeidimo samprata , po to atsižvelgiant į sisteminį Darbo kodekso aiškinimą bei LAT suformuotas kryptis bandoma atskleisti, pagal kokius požymius, kriterijus kiti nusižengimai priskiriami prie šiurkščių darbo pareigų pažeidimų, kurie nėra išvardinti Darbo kodekse. Darbe svarbu išskirti kokie aktualiausi klausimai dėl šio straipsnio 11 punkto taikymo ir kaip LAT išvados susijusios su teisiniu reglamentavimu, pažymėti kiek tai aktualu. Šiurkštaus darbo pareigų pažeidimo institutas darbo teisėje itin svarbus tuo, kad suteikia teisę darbdaviui už vienkartinį šiurkštų darbo pareigų pažeidimą paskirti darbuotojui griežčiausią drausminę nuobaudą – atleidimą iš darbo. Todėl šis darbas yra naudingas ir tuo, kad be... [toliau žr. visą tekstą] / The institute of the rude work duty violation just recently has appeared in the Labor Law - when the new Labor Code came into effect. The concept of this violation and the consolidation of the non-finite list of the rude work duty violation cause many problems in applying those rules of law in the practice. The definition of the rude work duty violation given in the Labor Code is not clear and comprehensive; the given list of violations is just an example; the position of legislator to consolidate other violations breaking the working order in a rude way causes various evaluation and interpretation problems. In the Labor Law doctrine and practice emerge the disagreements regarding those other cases mentioned in the Article 235 Section 2 Clause 11 of the Labor Code. Therefore in this work the concept of the rude work duty violation is being analyzed at first and later, regarding the systemic Labor Code explanations and the directions given by the Supreme Court of Lithuania, there are attempts to reveal the features and criterions according which other violations which are not listed in the Labor Code are attributed to the rude work duty violation. In this work it was important to highlight the most actual questions regarding the application of the clause 11 of this article and to explain how the conclusions of the Supreme Court of Lithuania are coherent with legal regulations and to reveal the relevance of it. The institute of the rude work duty violation is very important in... [to full text]
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États collectifs de I'²³⁵U excités dans la capture radiative de neutrons thermiques par I'²³⁴U.Almeida, José J.M., January 1900 (has links)
Th. 3e cycle--Phys. nucl.--Grenoble 1, 1978. N°: 18.
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Σύνθεση ζεολιθικών υμενίων στην επιφάνεια μαγνητοελαστικών ελασμάτων για την ανίχνευση πτητικών οργανικών ουσιών και τον προσδιορισμό της επίδρασης της ρόφησης στις μηχανικές ιδιότητες του υμενίουΜπάιμπος, Θεόδωρος 17 September 2012 (has links)
Στη παρούσα διατριβή πραγματοποιήθηκε ανάπτυξη αισθητήρων που αποτελούνται
από μαγνητοελαστικό έλασμα τύπου Metglas στην επιφάνεια του οποίου έγινε επικάλυψη με ευαίσθητο εκλεκτικό υμένιο. Στη μεγάλη πλειοψηφία των περιπτώσεων ως τέτοιο υμένιο χρησιμοποιήθηκε ζεόλιθος. Διαφορετικοί τύποι ζεόλιθων συνετέθησαν έπειτα από υδροθερμική σύνθεση και προσκολλήθηκαν ισχυρά στην εξωτερική επιφάνεια (και από τις δύο πλευρές) των Metglas. Ένας τέτοιος αισθητήρας συνδυάζει τις ροφικές ικανότητες του εκλεκτικού υμενίου με την ιδιότητα του Metglas να μετατρέπει φορτίσεις μάζας και αλλαγές των ελαστικών ιδιοτήτων του σε μετρούμενες μεταβολές της συχνότητας συντονισμού του. Η συνδυασμένη αυτή ικανότητα του αισθητήρα χρησιμοποιήθηκε για την ανίχνευση Πτητικών Οργανικών Ουσιών (VOC’s). Πιο συγκεκριμένα για τον ίδιο σκοπό χρησιμοποιήθηκαν υμένια ζεόλιθων (FAU, MFI και LTA) και πολυμερούς (Bayhydrol-110). Τα VOC’s των οποίων η ανίχνευση εξετάστηκε με τους παραπάνω αισθητήρες είναι: αιθυλεστέρας, πάρα-ξυλόλιο, όρθο-ξυλόλιο, βενζόλιο, κυκλο-εξάνιο, κανονικό-εξάνιο, προπάνιο και προπυλένιο. Δεύτερος στόχος της διατριβής ήταν ο υπολογισμός μηχανικών ιδιοτήτων των ζεόλιθων. Στη βιβλογραφία έχει αποδειχθεί ότι η ρόφηση αερίων επηρεάζει (εκτός από τη μάζα του) και τις μηχανικές ιδιότητες των ζεόλιθων μέσω της μεταβολής του μεγέθους της μοναδιαίας κυψελίδας των. Επομένως η ρόφηση αναμένεται να επηρεάζει εφαρμογές τους (π.χ ζεολιθικές μεμβράνες), των οποίων η απόδοση εξαρτάται άμεσα από τις μηχανικές τους ιδιότητες. Για το λόγο αυτό αναπτύχθηκε πειραματική μεθοδολογία με την οποία υπολογίζονται το μέτρο ελαστικότητας Ε των ζεολιθικών φιλμ, και οι τάσεις/παραμορφώσεις που αναπτύσσονται στο ζεολιθικό υμένιο κατά τη ρόφηση αερίων. Ο υπολογισμός για την εύρεση του μέτρου ελαστικότητας βασίζεται στη καταγραφή των μεταβολών της συχνότητας συντονισμού fR πολλαπλών αισθητήρων Metglas/ζεόλιθος διαφορετικού πάχους υμενίου ο καθένας. Η συγκεκριμένη μέθοδος γενικεύεται και βρίσκει εφαρμογή για τον υπολογισμό του μέτρου ελαστικότητας E του Young οποιαδήποτε μικροπορώδους ομοιόμορφου και καλά προσκολλημένου στην επιφάνεια του Metglas υμενίου. Ο υπολογισμός των τάσεων που αναπτύσσονται στο φιλμ κατά τη ρόφηση επιτυγχάνεται με χρήση δύο διαφορετικών μεθόδων. Η πρώτη μέθοδος, εφαρμόζεται σε αισθητήρες στους οποίους επικάλυψη με συνεχές υμένιο ζεόλιθου υπήρχε και από τις δύο πλευρές του Metglas. Με συνδυασμένη χρήση κατάλληλης θεωρίας και μαθηματικού μοντέλου της βιβλιογραφίας για τα μαγνητοελαστικά υλικά υπολογίζονται οι τάσεις που αναπτύσσονται στους ζεόλιθους FAU, LTA και σιλικαλίτη-1 κατά τη ρόφηση υγρασίας. Η δεύτερη μέθοδος υπολογισμού τάσεων εφαρμόστηκε σε αισθητήρα Metglas/MFI, στον οποίο επικάλυψη με συνεχές υμένιο ζεόλιθου υπήρχε μόνο από τη μία πλευρά του ελάσματος. Η μέθοδος εφαρμόζεται σε αισθητήρα Metglas/MFI κατά τη ρόφηση VOC’s, και βασίζεται στην ευκαμψία και ελαστικότητα που επιδεικνύει ο συγκεκριμένος αισθητήρας κατά τη διεργασία αυτή. Η διαφοροποίηση των δύο επιφανειών ως προς την ομοιομορφία του φιλμ του αισθητήρα, σε συνδυασμό με τη ρόφηση προκαλούν τη κάμψη του, ορατή ακόμα και με γυμνό μάτι, από το μέγεθος της οποίας υπολογίζονται οι τάσεις που αναπτύσσονται στο φιλμ του ζεόλιθου. Σε όλες τις περιπτώσεις ακολουθεί σύγκριση των πειραματικών αποτελεσμάτων μας με τη βιβλιογραφία. / In the current thesis the development of sensors comprised of magnetoelastic ribbon (Metglas) its surface was coated with selective sensitizing layer was examined. In most cases, zeolites were selected as sensitive layers. Different types of zeolites were synthesized and bounded in both outer surfaces of Metglas using the hydrothermal synthesis technique. Such a sensor combines the adsorptive abilities of sensitizing layer with the inner ability of Metglas to convert mass loadings and changes in the elastic properties in corresponding changes of the measured resonance frequency of the ribbon. That combined ability has been used for the detection of Volatile Organic Compounds (VOC’s). More particularly, for the same purpose zeolite layers (FAU, MFI and LTA) and polymer (Bayhydrol-110) have been used. The detected VOC’s are: ethyl-acetate, para-xylene, ortho-xylene, benzene, cyclohexane, n-hexane, propane and propylene. The second target of the current thesis was the calculation of mechanical properties of zeolites. In the literature has been proved that gas adsorption upon zeolites affects not only its mass but also its mechanical properties through the unit cell changes. Thus, adsorption is expected to affect applications such as zeolite membranes the performance of which is directly affected by their mechanical properties and possible changes. Hence, a new method is proposed which unable the calculation the Young modulus of zeolite films, and the stresses/deformations induced in the zeolite film upon adsorption. The calculation of Young modulus is based on the recording of resonance frequency changes of multiple sensors with different zeolite thickness each. The methodology is general and can be used for measuring Young modulus of any microporous film as long as it can be deposited as uniform layer on a magnetoelastic ribbon. The calculation of adsorption induced stresses is succeeded with two different methods. The first method is applied in sensors in which zeolite coating existed on both surfaces of Metglas ribbon. Combined use of appropriate theory and mathematical model from the literature for the magnetoelastic materials, stresses induced on FAU, LTA and silicalite-1 zeolites upon humidity adsorption were calculated. The second method was applied in Metglas/MFI sensor in which uniform polycrystalline MFI layer existed only from the one side of the ribbon. The method was applied during the adsorption of VOC’s and is based on the bending and elasticity shown by the sensor during the adsorption process. The differentiation of the two surfaces concerning the cohesion of the film, combined with adsorption phenomena cause remarkable bending, visible even with a naked eye, from the magnitude of which stresses induced on zeolite film are calculated. In all cases there is a comparison of our experimental results with corresponding from the literature.
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