Les couches minces du silicium présentent de nombreux avantages dans la course à la production de modules solaires à grande échelle de part leur consommation très réduite de matière, leur faible coût de production et leur pertinence dans la technologie solaire flexible. Le silicium microcristallin hydrogéné (c-Si:H), préparé par dépôt chimique en phase vapeur (PECVD), a suscité un intérêt croissant grâce à sa stabilité contre la dégradation induite par la lumière et sa meilleure absorption comparées à celles du silicium amorphe. La structure mixte de ce matériau constituée du silicium amorphe et de grains cristallins arrangés sous forme d'agrégats coniques ou colonnaires influe sur les mécanismes du transport électrique.Dans cette thèse, un modèle tridimensionnel de croissance du c-Si:H est utilisé pour reproduire les principales caractéristiques de la dynamique de croissance et la microstructure du c-Si:H : une forme conique ou colonnaire des grains, une zone de transition amorphe nanocristalline, une rugosité de surface et une fraction cristalline qui évoluent avec l'épaisseur.Un modèle de transport électrique tridimensionnel utilisant les matériaux générés est développé. Ce modèle met en jeu des paramètres électriques correspondant au transport dans la phase amorphe, cristalline et au travers des joints de grains. Les résultats de la simulation sont comparés aux mesures de conductivité électrique montrant un excellent accord et permettant d'extraire les caractéristiques de la barrière de potentiel formée entre les grains. Cette modélisation numérique, à la fois du processus de la croissance et du comportement électrique permet de contribuer à une meilleure compréhension des phénomènes de transport dans ces matériaux fortement hétérogènes.Une caractérisation en bruit basse fréquence des couches microcristallines ayant différentes fractions cristallines est menée dans le but de mieux appréhender les mécanismes de transport. Le comportement en bruit trouvé est typique d'un phénomène de percolation.Les contacts métalliques utilisés lors des caractérisations électriques sont étudiés par la méthode TLM. La modélisation numérique de la structure de test a permis d'extraire la résistivité de contact et la résistance carrée des couches. Nos résultats suggèrent un processus de percolation à l'interface métal/c-Si:H. / Silicon thin films present many advantages in the production of large scale solar cells due to their very low material consumption, low production cost and their relevance in the flexible solar technology. The hydrogenated microcrystalline silicon (c-Si:H) prepared by chemical vapor deposition (PECVD ), has attracted increasing interest due to its stability against degradation induced by light and its better absorption compared to amorphous silicon . The mixed structure of this material consisting of amorphous silicon and crystalline grains arranged in the form of conical or columnar aggregates affects the electrical transport mechanisms. In this thesis, a three-dimensional model is used to reproduce the main features of the growth dynamics and the microstructure of c-Si:H: conical or columnar grains, an amorphous/nanocrystalline transition zone, a surface roughness and a crystalline fraction evolving with the thickness. A three-dimensional model of the electrical transport using the generated structures is developed. This model involves electrical parameters corresponding to the transport in the amorphous phase, crystalline phase and through the grain boundaries. The simulation results are compared to the electrical conductivity measurements showing an excellent agreement and allowing to extract the characteristics of the potential barrier formed between the grains. The numerical modeling of both the process of growth and the electrical behavior contributes to a better understanding of transport phenomena in these highly heterogeneous materials.A low frequency noise characterization of microcrystalline silicon layers with different crystalline fractions has been performed in order to understand the transport mechanism. The noise behavior is found to be typical of a percolation phenomenon.The metallic contacts used in the electrical characterizations are studied by the TLM method. Numerical modeling of the test structure allows extracting the contact resistivity and the sheet resistance of the films. Our results suggest a percolation process on the metal / c-Si:H interface.

Το μικροκρυσταλλικό υδρογονωμένο πυρίτιο (μc-Si:H) βρίσκει εφαρμογή ως ενδογενής ημιαγωγός σε φωτοβολταϊκές ιδιοσυσκευές λεπτών υμενίων πυριτίου απλής και ανάστροφης δομής (tandem). Η τυπική μέθοδος παρασκευής του υλικού είναι η χημική εναπόθεση ατμών ενισχυμένη με πλάσμα (Plasma Enhanced Chemical Vapor Deposition – PECVD) με χρήση χωρητικών εκκενώσεων υψηλής αραίωσης σιλανίου (SiH4) σε υδρογόνο (H2). Εξαιτίας της χαμηλής απορρόφησης στο ορατό φάσμα απαιτείται αρκετά μεγάλο πάχος της ενδογενούς στοιβάδας του μc-Si:H, ωστόσο με τα υπάρχοντα δεδομένα οι ρυθμοί εναπόθεσης είναι αρκετά χαμηλοί με αποτέλεσμα οι χρόνοι εναπόθεσης να είναι απαγορευτικοί για τη βιομηχανία. Έτσι γίνεται επιτακτική η ανάγκη για υψηλούς ρυθμούς εναπόθεσης (> 5 Å/s) ούτως ώστε να είναι εφικτή η παραγωγή φωτοβολταϊκών κελιών χαμηλού κόστους. Σκοπός της παρούσας εργασίας είναι η μελέτη εναλλακτικών τεχνικών ενίσχυσης του ρυθμού εναπόθεσης λεπτών υμενίων μc-Si:H όπως η χρήση πηγής πλάσματος υψηλής πυκνότητας ηλεκτρονίων (Hollow Cathode) και η χρήση δισιλανίου (Si2H6) ως επιπρόσθετο του τυπικού μίγματος SiH4/H2. Στο πρώτο μέρος παρουσιάζεται η κατασκευή δύο ηλεκτροδίων hollow cathode διαφορετικής γεωμετρίας και ο ηλεκτρικός χαρακτηρισμός τους σε εκκενώσεις Η2 με σκοπό τη βελτίωση της γεωμετρίας της πηγής και των συνθηκών στις οποίες επιτυγχάνεται υψηλή πυκνότητα ηλεκτρονίων στην εκκένωση. Επιπλέον παρουσιάζονται μετρήσεις ρυθμού εναπόθεσης λεπτών υμενίων με την πηγή hollow cathode διερευνώντας διαφορετικές παραμέτρους της διεργασίας και πραγματοποιείται σύγκριση με την προϋπάρχουσα πηγή χωρητικής σύζευξης. Αποδείχθηκε ότι με τη χρήση καθοδικών κοιλοτήτων μεγάλης διαμέτρου (20 mm) η πυκνότητα των ηλεκτρονίων αυξάνει σημαντικά και οι ρυθμοί εναπόθεσης είναι έως και τρεις φορές υψηλότεροι σε σχέση με την πηγή χωρητικής σύζευξης. Στο δεύτερο μέρος παρουσιάζεται η επίδραση της προσθήκης μικρής ποσότητας Si2H6 στο μίγμα SiH4/H2 στο ρυθμό εναπόθεσης και την κρυσταλλικότητα των λεπτών υμενίων πυριτίου, πραγματοποιείται βελτιστοποίηση της διεργασίας όσον αφορά την πίεση και συγκρίνεται η χρήση Si2H6 με την αύξηση της παροχής του μίγματος SiH4/H2. Η προσθήκη Si2H6 σε περιοχή πιέσεων 2-3 Torr αποδείχθηκε ευεργετική για το ρυθμό εναπόθεσης των υμενίων (έξι φορές αύξηση) λόγω ενίσχυσης της πυκνότητας ηλεκτρονίων και του ρυθμού διάσπασης του SiH4. Επίσης η προσθήκη Si2H6 οδηγεί σε υψηλότερη απόδοση εναπόθεσης συγκριτικά με την αύξηση της συνολικής παροχής του μίγματος SiH4/H2 ή της περιεκικότητας σε SiH4. / Microcrystalline hydrogenated silicon (μc-Si:H) is widely used as intrinsic layer in thin film solar cells of single or tandem structure. This material is most commonly produced via Plasma enhanced Chemical Vapor Deposition (PECVD) from highly diluted silane (SiH4) in hydrogen (H2). However, the rather low absorption coefficient of the intrinsic material in the visible spectrum imposes higher layer thickness in order to ensure high device efficiency. The key obstacle for the production of cost-effective solar cells is the relatively low growth rate of the intrinsic μc-Si:H and thus the research is focused on the increase of the deposition rate while maintaining the thin film quality. In this work we aim to study alternative techniques in order to enhance the μc-Si:H thin films growth rate such as the utilization of high electron density plasma source (hollow cathode) and the small disilane (Si2H6) addition to the SiH4/H2 gas mixture. In the first part is presented the construction of two novel hollow electrodes and their electrical characterization in H2 discharges aiming to investigate the conditions that ensure a high electron density in the discharge. Moreover, deposition rate measurements are presented for the hollow cathode source and compared to the already existing CCP source. It was proved that for the larger hollows (20mm diameter) the average electron density increased abruptly and the corresponding deposition rate was about 3 times higher comparatively to the CCP source. In the next part of this study is presented the effect of the small Si2H6 addition to the gas mixture to the silicon thin films growth rate and crystallinity, the process is optimized in terms of the total gas pressure and compared to the case of the SiH4/H2 total flow rate increase. The small Si2H6 addition in the narrow pressure region of 2-3 Torr proved beneficial for the film growth rate (six times increase) due to the sharp enhancement of the electron density and the SiH4 dissociation rate. The Si2H6 addition also resulted in much higher deposition efficiency as compared with the increase of the SiH4/H2 flow rate or the SiH4 molar fraction.

Microcrystalline cellulose (MCC) is the most commonly used excipient in the manufacture of spherical particles or beads by extrusion spheronisation. However, the use of MCC in beads has its limitations such as prolonged release of drugs due to lack of disintegration. The aim of this study was to determine if Aloe vera and Aloe marlothii leaf materials can be used as excipients in the production of beads prepared by extrusion spheronisation. A 23 full factorial design was employed for optimisation and to explore the effects of the concentration of MCC, polyvinylpyrrolidone and aloe materials on the sphericity and release rate of ketoprofen. Scanning electron microscopy revealed more porous beads when aloe materials were included in the bead formulations compared to the formulation with MMC alone. The bead formulations containing aloe materials exhibited faster drug release compared to that of the formulation containing MCC alone. Dissolution data of the optimised formulations were analysed in terms of mean dissolution time (MDT) as well as fit factors (f1 and f2). The optimised bead formulations had dissolution profiles comparable to that of the formulation containing MCC alone at pH 1.2 and 4.5 (f2 values > 70), but less comparable to the reference at pH 6.8 (50 < f2< 65) due to faster drug release. Aloe vera and Aloe marlothii leaf materials can be used successfully together with MCC in the production of beads by extrusion spheronisation. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Microcrystalline cellulose (MCC) is the most commonly used excipient in the manufacture of spherical particles or beads by extrusion spheronisation. However, the use of MCC in beads has its limitations such as prolonged release of drugs due to lack of disintegration. The aim of this study was to determine if Aloe vera and Aloe marlothii leaf materials can be used as excipients in the production of beads prepared by extrusion spheronisation. A 23 full factorial design was employed for optimisation and to explore the effects of the concentration of MCC, polyvinylpyrrolidone and aloe materials on the sphericity and release rate of ketoprofen. Scanning electron microscopy revealed more porous beads when aloe materials were included in the bead formulations compared to the formulation with MMC alone. The bead formulations containing aloe materials exhibited faster drug release compared to that of the formulation containing MCC alone. Dissolution data of the optimised formulations were analysed in terms of mean dissolution time (MDT) as well as fit factors (f1 and f2). The optimised bead formulations had dissolution profiles comparable to that of the formulation containing MCC alone at pH 1.2 and 4.5 (f2 values > 70), but less comparable to the reference at pH 6.8 (50 < f2< 65) due to faster drug release. Aloe vera and Aloe marlothii leaf materials can be used successfully together with MCC in the production of beads by extrusion spheronisation. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

O intumescimento é um dos fatores decisivos que influenciam o comportamento de desintegração de formas farmac6uticas compactadas e, consequentemente, o perfil biofarmacêutico de substancias ativas. Entre os diversos adjuvantes empregados para promover a desagregação daquelas formas farmac6uticas nas suas partículas primarias originais, são utilizadas varias substancias, abrangidas pelo conceito de desintegrantes intumescedores. A escolha do adjuvante mais adequado nestes casos pode ser vista como uma atividade que exige o gasto considerável de tempo e de custos elevados. Além disto deve ser levada em consideração a existência de vários produtos similares no mercado. A questão da equival6ncia representa portanto um desafio importante na fase de formulação. Com o objetivo de aumentar os conhecimentos nesta área, foi desenvolvido equipamento para a avaliação dinâmica do intumescimento de pês. Inicialmente foram considerados fatores de construção do aparelho, tais como a porosidade, espessura e área do filtro de vidro sintetizado. Foram tamb6m avaliadas variações metodológicas, entre as quais a temperatura de realização do teste e o meio liquido empregado. Croscarmelose, um superdesintegrante, foi utilizada como adjuvante-modelo no teste do equipamento. A alteração do meio liquido de ensaio foi o fator que causou a maior influ6ncia sobre os resultados, embora a espessura dos filtros de vidro sintetizado tenha causado alguma alteração quer no tempo como no volume final de intumescimento. intumescimento. Já a mudança de temperatura não provocou diferenças significativas nas observações. Numa segunda fase foi investigada a influência deste desintegrante sobre as características de intumescimento de quatro celuloses microcristalinas (CMCr) isoladas ou adicionadas com um lubrificante. Para tanto elaborou-se um planejamento fatorial 4 X 2 X 2. A presença do desintegrante, como esperado, provocou aumento do volume final de intumescimento das CMCr, que apresentaram, no entanto, comportamentos diferenciados frente ao adjuvante. Já a presença do lubrificante conduziu a resultados totalmente dependentes do tipo de CMCr testada. A análise comparativa entre estes produtos demonstrou que somente num caso houve simitaridade de comportamento. / Swelling is one of the decisive factors influencing the disintegrant behavior of compacted pharmaceutical dosage forms and consequently the biopharmaceutical profile of drug substances. Among the various excipients used to promote the disintegration of such dosage forms in its originally primary particles, several substances, classified as swelling disintegrants, are employed. The choice of the most appropriate excipient in this case can be a time and cost consuming enterprise. Additionally it must be considered that the same substance can be delivered in the market by different producers. The question of equivalence represents also an important challenge in the formulation phase. In order to provide more knowledge in this area an apparatus to analyze the dynamic swelling of powder admixtures was developed. Construction factors such as filter porosity, thickness and area were considered. Methodological variants including essay temperature and liquid medium were also evaluated. Croscarmelose, a superdisintegrant, was used as model excipient to test the self built equipment. The change of the test fluid was the determinant factor on the results, although the thickness of the sintered glass filter showed some influence on both swelling volume and swelling time of this adjuvant. As a second step, the influence of this disintegrant on the swelling behavior of four microcrystalline celluloses (MCC) alone or added with a lubricant were investigated by using a 4 X 2 X 2 factorial design. The presence of the disintegrant was able to increase the swelling volume. Both final swelling volume and time were dependent of the MCC type. The lubricant showed different influences on the four tested MCC. A comparative study demonstrated that only in one case these products presented similarly swelling behavior.

O intumescimento é um dos fatores decisivos que influenciam o comportamento de desintegração de formas farmac6uticas compactadas e, consequentemente, o perfil biofarmacêutico de substancias ativas. Entre os diversos adjuvantes empregados para promover a desagregação daquelas formas farmac6uticas nas suas partículas primarias originais, são utilizadas varias substancias, abrangidas pelo conceito de desintegrantes intumescedores. A escolha do adjuvante mais adequado nestes casos pode ser vista como uma atividade que exige o gasto considerável de tempo e de custos elevados. Além disto deve ser levada em consideração a existência de vários produtos similares no mercado. A questão da equival6ncia representa portanto um desafio importante na fase de formulação. Com o objetivo de aumentar os conhecimentos nesta área, foi desenvolvido equipamento para a avaliação dinâmica do intumescimento de pês. Inicialmente foram considerados fatores de construção do aparelho, tais como a porosidade, espessura e área do filtro de vidro sintetizado. Foram tamb6m avaliadas variações metodológicas, entre as quais a temperatura de realização do teste e o meio liquido empregado. Croscarmelose, um superdesintegrante, foi utilizada como adjuvante-modelo no teste do equipamento. A alteração do meio liquido de ensaio foi o fator que causou a maior influ6ncia sobre os resultados, embora a espessura dos filtros de vidro sintetizado tenha causado alguma alteração quer no tempo como no volume final de intumescimento. intumescimento. Já a mudança de temperatura não provocou diferenças significativas nas observações. Numa segunda fase foi investigada a influência deste desintegrante sobre as características de intumescimento de quatro celuloses microcristalinas (CMCr) isoladas ou adicionadas com um lubrificante. Para tanto elaborou-se um planejamento fatorial 4 X 2 X 2. A presença do desintegrante, como esperado, provocou aumento do volume final de intumescimento das CMCr, que apresentaram, no entanto, comportamentos diferenciados frente ao adjuvante. Já a presença do lubrificante conduziu a resultados totalmente dependentes do tipo de CMCr testada. A análise comparativa entre estes produtos demonstrou que somente num caso houve simitaridade de comportamento. / Swelling is one of the decisive factors influencing the disintegrant behavior of compacted pharmaceutical dosage forms and consequently the biopharmaceutical profile of drug substances. Among the various excipients used to promote the disintegration of such dosage forms in its originally primary particles, several substances, classified as swelling disintegrants, are employed. The choice of the most appropriate excipient in this case can be a time and cost consuming enterprise. Additionally it must be considered that the same substance can be delivered in the market by different producers. The question of equivalence represents also an important challenge in the formulation phase. In order to provide more knowledge in this area an apparatus to analyze the dynamic swelling of powder admixtures was developed. Construction factors such as filter porosity, thickness and area were considered. Methodological variants including essay temperature and liquid medium were also evaluated. Croscarmelose, a superdisintegrant, was used as model excipient to test the self built equipment. The change of the test fluid was the determinant factor on the results, although the thickness of the sintered glass filter showed some influence on both swelling volume and swelling time of this adjuvant. As a second step, the influence of this disintegrant on the swelling behavior of four microcrystalline celluloses (MCC) alone or added with a lubricant were investigated by using a 4 X 2 X 2 factorial design. The presence of the disintegrant was able to increase the swelling volume. Both final swelling volume and time were dependent of the MCC type. The lubricant showed different influences on the four tested MCC. A comparative study demonstrated that only in one case these products presented similarly swelling behavior.

Orientador: Vitor Baranauskas / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T13:04:37Z (GMT). No. of bitstreams: 1 Pinto_MarcioAugustoSampaio_M.pdf: 3334021 bytes, checksum: e3031df53e18ad072ffc8cbe1486889f (MD5) Previous issue date: 2007 / Resumo: Apresentamos neste trabalho o desenvolvimento de filmes de diamante crescidos com adição de enxofre. Foram crescidos por deposição química a partir da fase vapor (diamante CVD) utilizando reatores do tipo filamento quente. Para a obtenção de diamante com condução do tipo-n, diluímos diferentes concentrações de dissulfeto de carbono (CS2) em etanol, cujo vapor foi arrastado para o reator pelo hidrogênio. Isto foi feito, pois o enxofre pode agir como doador em diamante. A espectroscopia Raman mostrou a boa qualidade dos filmes de diamante crescidos mesmo com o aumento da concentração de CS2. Ocorreu o deslocamento do pico do diamante indicando que houve um aumento médio nos comprimentos das ligações detectadas nas amostras, possivelmente devido à expansão da rede do diamante pela incorporação do enxofre. As imagens revelam uma perda da cristalinidade das amostras intermediárias e o ótimo facetamento das amostras iniciais e finais (baixa e alta concentração de CS2). Medidas elétricas pela sonda de quatro pontas revelaram que quanto mais o CS2 era adicionado, mais a resistividade dos filmes produzidos diminuía e que depois voltou a subir nas últimas amostras. Ao tratar as amostras com ácidos nítrico e sulfúrico para fazer medidas por efeito Hall, elas se tornaram isolantes. Esse fato revela que o banho removeu o material condutor e que pode ser devido à dopagem com enxofre nas áreas superficiais e intergranulares dos filmes. Medidas por efeito Hall de amostras que foram crescidas ao mesmo tempo das amostras tratadas pelo banho, mas sem passar por ele, apresentaram uma condução do tipo-p devido aos buracos, da mesma forma que as amostras relatadas em artigos na literatura em que não houve contaminação com boro, seja ela involuntária ou voluntária. Apresentaram também alta densidade de portadores e uma mobilidade razoável. A incorporação do enxofre no filme de diamante foi confirmada por medidas de XRF e de PIXE. O aumento do enxofre incorporado no filme não foi proporcional às crescentes concentrações de CS2. Isto sugere que nem todo átomo de enxofre é eletricamente ativo, isto é, nem todo enxofre age como um dopante nos filmes de diamante. Estudos recentes revelam que a presença do boro nas dopagens com enxofre têm sido decisiva na obtenção de diamante do tipo-n / Abstract: We present in this work the development of grown diamond films with sulphur addition. They had been grown by chemical deposition from the vapor phase (diamond CVD) using reactors of the type hot filament. For the diamond attainment with conduction of the n-type, we diluted different concentrations of carbon disulfide (CS2) in ethyl alcohol, whose vapor was dragged into reactor by hydrogen. This was done, due to the fact that sulphur can act as a donor in diamond. The Raman spectroscopy showed exactly the good quality of the grown diamond films with the increase of the CS2 concentration. The displacement of the peak of the diamond occurred indicating that it had an average increase in the lengths of the linkings detected in the samples, possibly due to the expansion of the lattice of the diamond for the incorporation of sulphur. The images presented to a loss of the crystallinity of the intermediate samples and the excellent good crystalline facets of the initial and final samples (low and high concentration of CS2). The electric measures in four-point probe methods showed that the higher the concentration of CS2 the lower the resistivity of the produced films was, and afterwards, it went up again in the last samples. When treating the samples with nitric and sulphuric acids to make the measures for Hall effect, they had become insulators. This fact discloses that the bath removed the conducting material and that can be due to doping with sulphur in the surface and intergrain areas of the films. The Hall effect measures of the samples that had been grown at the same time of the samples treated for the bath, but without being through it, presented a conduction of the p-type due to the holes, in the same way that the samples described in articles in literature where they did not have contamination with boron, either involuntary or voluntary. They had also presented high density of carriers and a reasonable mobility. The incorporation of sulphur in the diamond film was confirmed by measures of XRF and PIXE. The increase of sulphur incorporated in the film was not proportional to the increasing concentrations of CS2. This suggests that nor all sulphur atom is electrically active, that is, not every sulphur acts as a dopant in the diamond films. Recent studies have disclosed that the presence of boron in the doping with sulphur has been decisive in the diamond attainment of the n-type / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

En milieu extérieur les objets en cuivre et alliages cuivreux subissent des altérations qui entraînent des modifications physiques et esthétiques de l’œuvre. Pour limiter ces dégradations il convient de réduire les interactions entre la couche de corrosion et son environnement d’exposition en appliquant un traitement de protection. Ce travail de thèse propose d’étudier deux types de traitements de protection : une cire microcristalline (cire Cosmolloïd) et des solutions de décanoate (NaC10 et HC10). Pour cette étude des échantillons « modèles » en cuivre naturellement corrodés ont été utilisés afin de développer une méthodologie analytique visant à étudier le mode d’action et la pénétration des deux types de traitement de protection appliqués sur des couches de corrosion. Grâce à cette méthodologie il a été observé que bien que l’action en surface varie en fonction de la nature du traitement, la pénétration quant à elle semble dépendre essentiellement de son mode d’application.Un travail de remise en corrosion des échantillons traités a également été mené en conditions d’immersion et en corrosion atmosphérique sous cyclage d’humidité relative, à l’aide de traceurs isotopiques (D2O et 18O), afin d’évaluer qualitativement et de comparer l’efficacité des différents traitements de protection. Des dégradations sous UVB et lixiviation des traitements ont également permis d’étudier la tenue des traitements dans des conditions d’exposition extérieure. La détection des traceurs isotopiques dans les couches de corrosion par ToF-SIMS et analyses NRA, bien que n’ayant pas permis de conclure à une meilleur efficacité d’un type de traitement par rapport à l’autre, ont tout de même révélé des différences de tenues. Tandis que la cire microcristalline se dégrade rapidement sous rayonnement UVB par rapport au traitement HC10, le phénomène de lixiviation semble en revanche dégrader plus rapidement un traitement demeuré en surface de la couche de corrosion. / In outdoor environment copper and copper alloys objects undergo degradations that lead to physical and aesthetic modifications of the artwork. To limit these changes interactions between the corrosion layer and its exposure environment should be reduced by applying protective treatment. This project proposes to study two types of protective treatments: microcrystalline wax (Cosmolloïd wax) and decanoate solutions (NaC10 and HC10). For this study, naturally corroded copper "model" samples were used to develop an analytical methodology to study the action and penetration of the two types of protective treatment applied to corrosion layers. This methodology allowed to observe that although the surface action changes according to the nature of the treatment, the penetration seems to depend essentially on its application.Re-corrosion experiments of treated samples was also carried out under immersion conditions and atmospheric corrosion with relative humidity cycling, both using isotopic tracers (D2O and 18O) in order to qualitatively evaluate and compare the effectiveness of the protective treatments. Degradations under UVB and leaching off treatments also lead to a study of their behavior under conditions of external exposure. The detection of isotopic tracers in the corrosion layers by ToF-SIMS and NRA analysis, even though it wasn’t allow to conclude to a better effectiveness of one treatment over the other, nevertheless revealed holding differences. While microcrystalline wax degrades rapidly under UVB radiation compared to HC10 treatment, the leaching phenomenon seems to degrade more rapidly a treatment remaining on the surface of the corrosion layer.

Title: Raman microspectroscopy of living cells and biological tissues Author: Šárka Moudříková Department / Institute: Institute of Physics of Charles University Supervisor of the doctoral thesis: doc. RNDr. Peter Mojzeš, CSc., Institute of Physics of Charles University Abstract: Raman microscopy combines Raman spectroscopy with optical confocal microscopy and thus provides information on chemical composition of a sample with a µm3 resolution. In this thesis, Raman microscopy has been used to study microalgae-unicellular photosynthetic organisms that are greatly relevant for the Earth's environment as well as for biotechnological applications. Raman microscopy of photosynthetic organisms struggles with a highly intensive background of the spectra, which is formed by fluorescence of cellular photosynthetic apparatus. In this thesis, we have developed a fast and reliable photobleaching method that suppresses the unwanted background; this method has enabled us to study intracellular distribution of algal biomolecules such as proteins, starch, lipids and polyphosphate. We have investigated an evolution of these structures during a cell cycle of a model microalga Desmodesmus quadricauda. Next, we have developed a method for quantitative analysis of polyphosphate in a cellular culture of a microalga Chlorella...

Amorphous and nano- or micro- crystalline silicon thin films are intensively studied materials for photovoltaic applications. The films are used as intrinsic layer (absorber) in p-i-n solar cells. As opposed to crystalline silicon solar cells, the thin films contain about hundred times less silicon and can be deposited at much lower temperatures (typically around 200 0 C) which saves energy needed for production and makes it possible to use various low cost (even flexible) substrates. However, these films have a complex microstructure, which makes it difficult to measure and describe the electronic transport of the photogenerated carriers. Yet, the understanding of the structure and electronic properties of the material at nanoscale is essential on the way to improve the efficiency solar cells. One of the main aims of this work is the study of the structure and mechanical properties of the mixed phase silicon thin films of various thicknesses and structures. The key parameter of microcrystalline silicon is the crystallinity, i.e., the microcrys- talline volume fraction. It determines internal structure of the films which, in turn, decides about many other properties, including charge transport and mechanical sta- bility. Raman microspectroscopy is a fast and non-destructive method for probing the...