Specific Interactions in Carbon Dioxide + Polymer Systems Anupama Kasturirangan 163 Pages Directed by Dr. Amyn S. Teja Weak complex formation in CO2 + polymer and CO2 + copolymer systems containing C=O and C-F groups was quantified using in situ FTIR spectroscopy. The enthalpy of interaction thus obtained was directly incorporated into a lattice model and compressibility effects were accounted for via ratio of free volumes in modified segment number. CO2 + fluropolymer phase behavior could be correlated within experimental error (AAD of about 2%) using the new model, a task that has been beyond the capability of published models and it was also possible to predict phase equilibria of CO2 + PLGA copolymer systems with a single parameter obtained by fitting cloud point behavior in a reference system (CO2 + PLA in this case).New data on sorption equilibria in several CO2 + PLGA systems were obtained using a quartz crystal microbalance (QCM) and new data on Tg depression in the CO2 + PLA system were also obtained using a high pressure DSC method and used to demonstarte that model parameters are valid over extended pressure ranges. The new compressible lattice model developed is thus able to correlate cloud points, sorption equilibria, glass transition temperatures, and melting points using a single parameter. The model is therefore likely to be beneficial in many applications involving CO2 + polymer systems including drug delivery and encapsulation, polymer coating, and membranes for natural gas separations.

Les biosenseurs sont des dispositifs analytiques utilisés pour la détection de reconnaissance moléculaire. Ils consistent en un élément biologique immobilisé en contact intime avec un transducteur approprié qui convertit un signal biochimique en un signal électrique quantifiable. Leur principe est basé sur la reconnaissance d'une ou plusieurs molécules d'intérêt en solution (le ligand), par un composant biologique (le récepteur) étroitement lié au substrat transducteur. Le senseur réagit aux interactions récepteur-ligand et produit un signal mesurable, généralement proportionnel à la concentration du ligand fixé. Les biosenseurs sont déjà utilisés dans beaucoup de domaines différents, notamment dans le domaine médical (diagnostique et thérapeutique), le contrôle de l’environnement, et l’analyse et le monitoring de processus biotechnologiques. <p><p>La recherche concerne la mise au point d’un nouveau type de biosenseurs polyvalents à haute performance. Ces senseurs utilisent un élément de transduction optique dont la surface a été fonctionnalisée en vue de permettre la détection sélective d'interactions récepteur-ligand ainsi que le dosage des molécules fixées aux récepteurs. La technique utilisée pour la détection et le dosage est celle de la Spectroscopie ATR-FTIR (Spectroscopie Infra Rouge à Transformée de Fourrier en Réflexion Total Atténuée). Le système permet la détection directe, en temps réel, et sans marquage des molécules ciblées. La spectroscopie ATR-FTIR fournit une analyse des molécules sur base de leur empreinte spectrale infra rouge (IR) caractéristique, ce qui offre une mine d'informations pour identifier les ligands. Ce nouveau système de biosenseur, appelé BIA-ATR (Biospecific Interaction Analysis – Attenuated Total Reflection) est original et offre des avantages majeurs par rapport à la plus part des biosenseurs commercialement disponibles. Il fournit à l’utilisateur le spectre IR entier du ligand étudié, permettant non seulement le dosage quantitatif de ce dernier, mais aussi d’identifier sa nature intrinsèque. Un autre avantage est sa grande sensibilité ;le senseur BIA-ATR peut détecter la fixation de petites molécules et dans certains cas, aussi les réactions chimiques associées. <p><p>Le potentiel de cette nouvelle technologie de senseur est évalué dans ce travail par son application à plusieurs systèmes d’intérêt biologique et médical :la détection de protéines en milieux complexes, appliquée à la détection du Facteur VIII de coagulation du sang impliqué dans l’hémophilie de type A ;la fixation d’une petite molécule, le phosphate (phosphorylation), sur l’ATPase gastrique, un récepteur protéique de grande taille responsable de la sécrétion d’acide dans l’estomac et la détection et dosage d’un antibiotique, la vancomycine, utilisé en soins intensifs hospitaliers dans les cas d’infections bactériennes sévères à Staphylocoques dorés.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Un-doped, Er3+ doped (TiO2:Er3+) as well as Er3+/Yb3+ co-doped (TiO2:Er3+/Yb3+) nanocrystals with different concentrations of RE3+ (Er3+, Yb3+) were successfully synthesized using the sol-gel method. The powder X-ray diffraction (XRD) spectra revealed that all undoped and doped samples remained in anatase after annealing at 400°C. The presence of RE3+ ions in the TiO2 host lattice was confirmed by conducting elemental mapping on the samples using Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectrometer (EDX), which was in agreement with X-ray photoelectron spectroscopy (XPS) results. Transmission electron microscope (TEM) images approximated particle sizes of the samples to be between 1.5 – 3.5 nm in diameter and this compares well with XRD analyses. Phonon quantification in TiO2 was achieved using Fourier transform infrared (FT-IR) spectroscopy. Optical bandgap from Ultraviolet/Visible/Near-Infrared was extrapolated from Kubelka-Munk relation and the narrowing of the bandgap for the doped samples as compared to the undoped sample was observed. The photoluminescence PL study of the samples revealed two emission peaks attributed to direct band-gap and defect-related emissions. A laser beam with 980 nm wavelength was used to irradiate the samples, and the displayed emission lines of the TiO2: Er3+ in the visible region of the electromagnetic spectrum confirmed up-conversion luminescence. Enhancement of up-conversion luminescence intensity due to Yb3+ co-doping was observed, indicating an efficient energy transfer process from the sensitizer Yb3+ to the activator Er3+. / Physics / M. Sc. (Physics)

Orientador: João Carlos Silos Moraes / Banca: Claudio Luiz Carvalho / Banca: Cecilia Pedroso Turssi / Resumo: As resinas compostas vêm sendo estudadas de longa data, sempre na procura de propiciar aos clínicos um melhor entendimento do seu processo de polimerização e a obtenção de melhores resultados nos procedimentos restauradores. A proposta deste trabalho foi determinar o grau de conversão, a microdureza e o coeficiente de expansão térmica das resinas restauradoras TPH Spectrum (Dentsply) e Filtek P60 (3M), em função da profundidade. Os materiais foram polimerizados por uma fonte de luz halógena durante 40 segundos em anéis de alumínio em diferentes espessuras (1, 2, 3 e 4 mm). O grau de conversão foi determinado através da espectroscopia no infravermelho próximo com transformada de Fourier, utilizando a razão entre bandas de absorção correspondentes às ligações duplas alifáticas e aromáticas. Para tanto, foram confeccionadas pastilhas contendo 20mg de resina e 150mg de KBr e os espectros foram obtidos em um espectrômetro Nexus 670 (Nicolet). As medidas de microdureza Vickers foram obtidas com um aparelho HMV 2000 (Shimadzu), utilizando uma amostra de cada espessura. A expansão térmica foi estudada através da técnica da extensometria. Os resultados mostraram que para as duas resinas ocorre uma diminuição no grau de conversão e na microdureza à medida que se aumenta a profundidade, como esperado. Para as medidas de expansão térmica, a resina Filtek P60 não apresentou diferenças significativas nas quatro profundidades, enquanto para a resina TPH Spectrum houve um aumento no coeficiente de expansão térmica com a profundidade. Não foi observada uma correlação entre o grau de conversão e a microdureza nas duas resinas estudadas. A determinação do grau de conversão através de espectros de absorção no infravermelho próximo mostrou-se mais preciso do que quando determinado a partir de espectros na região infravermelho médio. / Abstract: The composite resins have been widely studied allowing a better understanding of the process of polymerization. As consequence, better results in the clinical procedures have been obtained. The purpose of this work was to study the degree of conversion, the hardness and the thermal expansion of the TPH Spectrum (Dentsply) and Filtek P60 (3M) resins in different depths. Samples were prepared for each resin using aluminum rings 10 mm in internal diameter and with different thickness (1, 2, 3, and 4 mm). Resin composites were cured with a halogen light curing unit for 40 s. The degree of conversion was determined from FTIR spectra by comparison of the aliphatic =CH2 bond at 4743 cm -1 with that of the aromatic component at 4623 cm -1 for the cured and uncured states. For that, pellets containing 20 mg of resin powder (cured or uncured) and 150 mg of KBr powder were made. The near infra-red spectra were obtained in a FT-IR spectrophotometer (model Nexus 670, Nicolet). The Vickers hardness was measured with a Micro Hardness Tester (model HMV 2000, Shimadzu). The thermal expansion was studied through the strain gauge technique. The results showed a decrease in the value of DC and hardness as increases the depth. For Filtek P60 resin, it was not observed significant difference in the coefficient of thermal expansion at different depths. On the other hand, an increase was observed in the coefficient as it increases the depth for the TPH Spectrum resin. There is not correlation between the conversion degree and the microhardness for the two studied resins. DC values more accurate were obtained from near infra-red spectra when compared with those obtained from medium infra-red spectra. / Mestre

Orientador: Laura Maria Mariscal Ottoboni / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T21:56:47Z (GMT). No. of bitstreams: 1 Ribeiro_DanielaAlves_D.pdf: 7458236 bytes, checksum: b0e036998f9e767306b90cf0ead49a47 (MD5) Previous issue date: 2011 / Resumo: Acidithiobacillus ferrooxidans e uma bacteria quimiolitotrófica, Gram-negativa e acidofílica que exerce um importante papel no processo de biolixiviação. O processo de biolixiviação e afetado por intempéries como variações na temperatura e na composição de nutrientes e, entender os mecanismos que A. ferrooxidans dispõe para sobreviver em ambientes extremos e de suma importância para melhorar o seu emprego no processo de biolixiviação. Neste trabalho foi estudada a resposta de A. ferrooxidans ao aumento da temperatura e a privação de fosfato. Para tanto, foram utilizadas técnicas baseadas em microscopia, espectroscopia no infravermelho, ferramentas proteômicas, PCR quantitativo e bioinformática. Pela microscopia eletrônica de varredura, verificou-se o alongamento das células de A. ferrooxidans, e a espectroscopia no infravermelho (FTIR) mostrou alterações em números de ondas entre 850 e 1275 cm-1, referentes a carboidratos, fosfolipídios e fosfoproteínas. A abordagem proteômica utilizada, uma combinação de eletroforese de duas dimensões e espectrometria de massas, identificou 44 proteínas diferencialmente expressas e pertencentes a 11 categorias funcionais. Dentre as proteínas com expressão aumentada foram identificadas algumas de resposta ao choque térmico. A técnica de PCR quantitativo em tempo real foi utilizada para avaliar o padrão de Expressão de genes do choque térmico e de outros genes que codificam proteínas pertencentes a diversas categorias funcionais em A. ferrooxidans. Para tanto, A. ferrooxidans foi cultivada a 40?C ate 50% de oxidação dos íons ferrosos (aproximadamente metade fase logarítmica) e também foi submetida a um choque térmico em diferentes tempos e na mesma temperatura. Os resultados obtidos mostraram que o padrão de expressão da maioria dos genes analisados foi afetado apos o choque térmico. Contudo, o crescimento a 40?C pouco afetou a expressão gênica, com exceção de alguns genes relacionados com o transporte de ferro, os quais foram consideravelmente reprimidos. Analises in silico para predição de sítios de ligação do fator sigma 32 da RNA polimerase nos genes afetados pelo aumento da temperatura indicaram que 15 do total de genes analisados possivelmente estão sob a regulação deste fator. Adicionalmente, analises da filogenia das sequências de aminoácidos de três "small heat shock proteins" (AFE_1437, AFE_1009 e AFE_2172) revelou que elas são, possivelmente, proteínas nao-paralogas. Estudos estruturais baseados em modelagem molecular por homologia indicaram que as proteínas AFE_1437, AFE_1009 e AFE_2172 possuem um domínio ?-cristalino com características estruturais semelhantes. Contudo, a proteína codificada por AFE_2172 apresenta uma região C-terminal bastante curta. Os resultados obtidos com este trabalho mostram que A. ferrooxidans possui um conjunto de respostas ao estresse muito bem elaborado, enfatizando seu potencial para uso biotecnológico / Abstract: Acidithiobacillus ferrooxidans is a chemolithoautotrophic, Gram negative, acidophilic bacterium which plays an important role in metal bioleaching. During bioleaching, cells are subjected to changes in growth temperature and nutrient starvation, thus understanding the mechanisms used for their survival in such harsh environments could help to improve Acidithiobacillus's efficacy on such processes. This study presents the effects of heat and phosphate starvation on A. ferrooxidans physiology, analysed using microscopy, infrared spectroscopy, proteomic tools, quantitative PCR and bioinformatics. Scanning electron microscopy results showed that under the tested stress conditions A. ferrooxidans cells became elongated, and the Fourier transform infrared spectroscopy (FT-IR) analysis showed alterations in wavenumbers between 850 and 1275 cm-1, which are related to carbohydrates, phospholipids and phosphoproteins. Proteomic analyses, such as 2-DE and tandem mass spectrometry, identified 44 differentially expressed protein spots, the identified proteins belonging to 11 different functional categories. The up-regulated proteins were mainly from the protein fate category. Real time quantitative PCR was employed to analyze changes in the expression patterns of heat shock genes, as well as many other genes encoding proteins related to several functional categories in A. ferrooxidans. Cells were submitted to long-term growth and to heat shock, both at 40°C. The results evidenced that heat shock affected the expression levels of most genes while long-term growth at 40°C caused minimal changes in gene expression patterns - with exception of some iron transport related genes, which were strongly down-regulated. Further bioinformatic analysis indicated a putative transcriptional regulation, by the ?32 factor, for 15 of the 34 heat-affected genes. In addition, phylogenetic analysis of some small heat shock proteins (AFE_1437, AFE_1009 e AFE_2172) showed that sHSPs from A. ferrooxidans are possible non paralogous proteins. Homology molecular modeling structure studies indicated that the proteins encoded by AFE_1437, AFE_1009, and AFE_2172 have conserved ?-crystallin domains. However, the model for AFE_2172 showed a very short C-terminus. These results evidence that A. ferrooxidans has an efficient range of stress-responses, which explains its ability for biotechnological purposes / Doutorado / Genetica de Microorganismos / Doutor em Genetica e Biologia Molecular

Breast cancer is the most common cancer in women. It is a highly heterogeneous disease in terms of histology, therapeutic response and patient outcomes. Early and accurate detection of breast cancer is crucial as the patient prognosis varies greatly depending on the diagnosis of the disease. Nonetheless current breast cancer classification methods fail to precisely sub-classify the disease, resulting in potential inadequate therapeutic management of patients and subsequent poor clinical outcomes. Substantial effort is therefore put in cancer research to develop methods and find new biomarkers efficiently identifying and characterizing breast tumor cells. Moreover it is now well-recognized that the intensive cross-talk between cancer cells and their microenvironment (including non-tumor cells) highly influences cancer progression. Recently, a growing body of clinical evidence reported the prognostic and predictive value associated with the presence of tumor infiltrating lymphocytes (TILs) in the microenvironment of breast tumors. Although the evaluation of TILs would be of great value for the management of patients and the development of new immunotherapies, it is currently not assessed in routine practice. Furthermore Fourier transform infrared (FTIR) imaging has shown its usefulness to study a panel of human cancers. Infrared (IR) spectroscopy coupled to microscopy provides images composed of multiple spectra reflecting the biochemical composition and subtle modifications within biological samples. IR imaging therefore provides useful information to improve breast cancer identification and characterization. The ultimate aim of this thesis is to improve breast cancer diagnosis using FTIR imaging to better identify and characterize cancer cells and the tumor microenvironment of breast cancers. In a first step we carried out a feasibility study aiming at evaluating the impact of the sample fixation process on IR spectra. While spectra were undeniably influenced by this biochemical alteration, our results indicated that closely-related cell types were influenced similarly and could still be discriminated on the basis of their spectral features. We then demonstrated the capability of IR imaging to discriminate a tumor from a normal tissue environment based on the spectral features of tumor cells and the surrounding extracellular matrix. A particular focus was placed on the identification of lymphocyte spectral signatures of cells isolated from blood or present within secondary lymphoid organs such as tonsils. Our results revealed that IR imaging was sensitive enough to discriminate lymphocyte subpopulations and to identify a particular spectral signature that we assigned to lymphocyte activation. Finally we highlighted the potential value of IR imaging as complementary tool to identify and characterize TILs in breast tumor samples. Altogether, our results suggest that IR imaging provides interesting and reliable information to improve breast cancer characterization and to assess the immune microenvironment of breast tumors.<p>/<p>Le cancer du sein est le carcinome le plus fréquent chez la femme. C’est une maladie très hétérogène du point de vue histologique, de la réponse thérapeutique et de l’évolution clinique. Une détection rapide et précise de la maladie est cruciale, un diagnostic du cancer du sein dès les premiers stades de la maladie permet une meilleure prise en charge du patient et est directement associé à un meilleur pronostic. Néanmoins la classification actuelle des cancers du sein ne permet souvent pas de caractériser la maladie de manière précise, ce qui donne lieu à la mise en place de traitements moins ciblés et une évolution clinique peu favorable. Pour remédier à cela, des efforts conséquents sont réalisés en recherche, dans le but de mettre au point des méthodes capables d’identifier et de caractériser les cellules tumorales. De plus il est actuellement reconnu que le micro-environnement tumoral (composé des cellules non-tumorales) influence fortement la progression du cancer. Récemment de nombreuses études ont montré que la présence de lymphocytes au niveau des tumeurs mammaires (TILs) était corrélée à un meilleur facteur pronostic et prédictif. Bien que l’évaluation des TILs soit de grande importance dans le cadre des immunothérapies, cet élément n’est actuellement pas pris en compte dans les analyses de routine. Par ailleurs, l’imagerie infrarouge par transformée de Fourier (FTIR) a démontré son utilité dans l’étude de plusieurs cancers humains. La spectroscopie infrarouge (IR) couplée à la microscopie fourni des images composées de multiples spectres qui reflètent la composition biochimique et les modifications dans les échantillons biologiques. De ce fait l’imagerie infrarouge procure des informations utiles pour améliorer l’identification et la caractérisation du cancer du sein. L’objectif général de cette thèse est d’améliorer le diagnostic du cancer du sein par imagerie FTIR pour mieux identifier et caractériser les cellules cancéreuses et le micro-environnement tumoral des tumeurs mammaires. Dans un premier temps nous avons effectué une étude de faisabilité afin d’évaluer l’impact du protocole de fixation des tissus sur les spectres IR. Bien que les spectres soient indéniablement influencés par cette altération biochimique, nos résultats indiquent que des types cellulaires proches sont influencés de manière similaire et peuvent donc être discriminés sur base de leurs caractéristiques spectrales. Nous avons ensuite démontré la capacité de l’imagerie IR de distinguer un environnement tumoral d’un environnement normal sur base des particularités spectrales des cellules tumorales et de la matrice extracellulaire. Une attention particulière a ensuite été portée afin d’identifier des signatures spectrales de cellules immunitaires du sang et au sein d’organes lymphoïdes secondaires, tels que les amygdales. Nos résultats ont révélé que l’imagerie IR permet d'identifier une signature spectrale particulière, que nous avons associée à une stimulation lymphocytaire. Finalement nous avons mis en évidence l’utilité de l’imagerie IR en tant qu’outil complémentaire pour identifier et caractériser les TILs dans les échantillons tumoraux mammaires. De manière générale, nos résultats suggèrent que l’imagerie IR fournit des informations intéressantes et fiables pour améliorer la caractérisation et l’évaluation du micro-environnement immunitaire dans les tumeurs mammaires. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

L'expérience nommée femto-FT-CEAS a été mise en place durant ce travail. Elle<p>combine une source d'absorption laser femto-opo, une cavité optique haute finesse<p>et un interféromètre à transformée de Fourier. Ce montage instrumental a permis<p>d'enregistrer des spectres sur un domaine de 100 cm−1 avec un coefficient d'absorption<p>minimal détectable de 5 10−10cm−1 pour des paramètres de résolution spectrale de<p>2 10−2cm−1 et un temps d'enregistrement d'une heure. Le coefficient d'absorption<p>equivalent par moyenne quadratique par élément spectral correspondant est de 1.2<p>10−12cm−1 Hz−1/2. Un chemin optique équivalent de 13 km a été obtenu dans une<p>cellule de 77 cm de long. La gamme spectrale accessible est de 6000 − 6700 cm−1 et<p>7800 − 8300 cm−1.<p>Les spectres enregistrés à l'aide du montage femto-FT-CEAS ont permis d'attribuer<p>plus de 1000 transitions rovibrationelles d'échantillons de CO2 enrichis en 17O,<p>d'OCS, CS2, H12C13CD, et CH3CCH. Les bandes suivantes ont été enrégistrées :<p>pour 12C17O2, les bandes 30013e, 30012e, 30011e, 31113e, 31113f, 31112e, 31112f,<p>et 31111e; pour 17O12C18O, les bandes 30013e, 30012e, et 30011e; pour 16O12C32S,<p>les bandes 540, 0, 501, 0, 511, 1e, 511, 1f, 601, 0, 460, 0, 421, 0, 431, 1e, 431, 1f,<p>521, 0, 341, 0, 351, 1e, 351, 1f, 302, 0, 312, 1e, 312, 1f, 402, 0, 322, 2e, et 322, 2f;<p>pour 16O12C34S, les bandes 501, 0 et 302, 0; pour 16O13C32S, la bande 302, 0 ;pour<p>16O12C33S, la bande 302, 0; pour 12C32S2, les bandes 0403, 0114, 3003 et 2203; pour<p>32S12C34S, la bande 3003. Les conventions de notation vibrationelles utilisées ici sont<p>pour CO2, ν1 ν2 l ν3 n où les bandes vibrationelles perturbées par la résonance de<p>Fermi ν1 2ν2 sont ordonnées selon n par ordre décroissant d'énergie. Pour l'OCS,<p>les conventions de notation sont ν1 ν2 ν3, l et pour le CS2, ν1 νl2 ν3. Leur analyse<p>spectrale a été réalisée, aboutissant à de nouvelles constantes rovibrationelles ou des<p>constantes améliorées par rapport à celles de la littérature. Les raies rovibrationnelles<p>attribuées sont données. L'analyse des spectres de H12C13CD et de CH3CCH a étéréalisée par l'équipe du Pr. L. Fusina (Université de Bologne, Italie).<p>L'expérience a aussi été installée autour d'un jet supersonique, enregistrant les<p>structures rotationnelles des bandes vibrationelles ν5 + ν9 de C2H4, 3ν3 de N2O et<p>ν1 + ν3 de H12C13CH en abondance naturelle, toutes avec une température rotationelle<p>inférieure à 35 K.<p>Finalement, un programme de simulation de ligne de base a été écrit. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

β-glucosidases are important components of the cellulase enzyme system in which they not only hydrolyse cellobiose to glucose, but also remove the feedback inhibition effects of cellobiose on exoglucanase and endoglucanase thereby increasing the rate of cellulose degradation to fermentable sugars. A total of 166 proteins were identified as β-glucosidases after manual BLASTp search on the Aspergillus comparative database from eight species. Evidence for Horizontal Gene Transfer (HGT) of bacterial origin of some β-glucosidase genes was provided by their lack of introns, absence of some fungal specific amino acid insertions in their sequences and unusual positions in phylogenetic trees showing similarities to bacterial proteins. A rapid plate assay based on Congo red methods was developed to study the optimum parameters such as pH and temperature for growth of strains and activities of the enzymes produced. Bacterial cellulose (BC) was produced by Gluconacetobacter xylinus. For the first time a fully detailed characterization by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), Differential scanning calorimeter (DSC), Thermogravimetric analysis (TGA) and 13Carbon Solid State Nuclear Magnetic Resonance (SSNMR) of pure BC before and after treatment with a commercially available Aspergillus cellulase enzyme was demonstrated. Two encoding sequences for novel Aspergillus nidulans hydrophobin genes ANID_05290.1 and ANID_07327 that do not fall into either the class I or class II category of hydrophobins were successfully cloned. Two encoding sequences for a novel β-glucosidase gene from an Aspergillus niger strain from Nigeria were amplified and cloned from genomic DNA using PCR. Aspergillus nidulans β-glucosidases (AN2227 and AN1804) expressed in Pichia were purified to homogeneity by using ammonium sulphate precipitation and DEAE-Sephadex A-50 chromatography. Both enzymes had a remarkably broad pH and temperature profile. Further experiments on the development of a technology for lignocellulose degradation based on co-production of β-glucosidase with hydrophobin for biofuel production are suggested.

In case of charge-transfer complex of TTF:TCNQ lot of work had previously been done on single crystals and thin films to study various interesting properties including phase transitions which were attributed to Peierls instability. But as seen from the review of molecular wires it is clear that apart from synthesis of TTF:TCNQ in molecular wire form, not much was known about the behavior of these wires at low temperatures. There were some open questions listed below, which we tried to address in the thesis Can nanowires of TTF:TCNQ be grown across prefabricated electrodes which are separated by gaps < 1 μm. Can the nanowires grown in such smaller gaps, show Peierls transition, which is the signature of quasi one dimensional conduction. As the size and length of the grown wires are small it was expected that they will have less staking disorder as compared to the thin films. What will be conduction mechanism at low temperatures in such single/few nanowire samples. If the nanowires show Peierls transition and CDW formation at low temperatures, can nonlinear conduction be seen due to motion of CDW, if so how well do they compare with the reported results for TTF:TCNQ single crystals. In case of Cu:TCNQ it can be noted from the above review that even though much advances have been made on synthesizing good quality Cu:TCNQ films and incorporating them in novel device structures, there has been much controversy regarding conduction mechanism. There were many conflicting results in literature regarding switching in these devices. In this thesis work we wanted to address the feasibility of switching in Cu:TCNQ under reduced size of top electrodes and also address few other issues like To grow Cu:TCNQ nanowires by using vapor phase evaporation method Can resistive switching be induced in Cu:TCNQ by using a local probe STM tip (Pt-Rh) operated in high vacuum. Since the measurement will be done in high vacuum what will be the effect of environment (absence of oxygen, water vapor) on reproducibility of resistive switching. Will localized switching depend on the top electrode material. This has been probed by coating different metals on the C-AFM tip and using them as top electrode in conducting mode. With what contact force will we get reproducible resistive switching. Can a device structure be made with an array of top electrode in the form of metal dots (< 10 μm) and study switching using C-AFM. This thesis is divided into seven main chapters and two appendix chapters, which are listed below: In the present chapter 1, a detailed overview and literature survey of charge-transfer complexes TTF:TCNQ and Cu:TCNQ which were relevant to our present study was presented. This was followed by our motivation in undertaking the present work. In chapter 2 the various experimental techniques developed during the course of the thesis work such as e-beam lithography, design of the vacuum chamber for deposition of organic molecules, design of ultra high vacuum scanning tunneling microscope (UHV-STM chamber along with the STM head, modification of conducting AFM for obtaining the switching data have been described. In chapter 3 we describe the preparation of TTF:TCNQ molecular wires across prefabricated electrodes and different measurements done on the samples. In particular the observation Peierls transition in the grown nanowires of TTF:TCNQ and the nonlinear conduction mechanism involved at low temperatures will be discussed in detail. In chapter 4 we describe the preparation of Cu:TCNQ nanowires on Cu substrate using vapor phase technique. Resistive switching measurements done on the Cu:TCNQ nanowires in high vacuum with Pt-Rh tip as top electrode will be discussed in detail. In chapter 5 we describe the resistive switching measurements performed on Cu:TCNQ nanowires with different metal coated C-AFM tips as well as FIB deposited platinum dots as top electrodes. In chapter 6 we make a few comments about possible switching mechanism involved, when STM tip, C-AFM induced as well as platinum coated dots were used as top electrodes. In chapter 7 we conclude this thesis by summarizing the main results. Also we point out the scope for future work that can be based upon the results presented in this work. In Appendix A a brief review of self assembled monolayer (SAM) of alkane thiols is presented followed by details about experiments done for insitu study of growth of SAMs of decanethiol and octadecanethiol on silver substrates using ellipsometry and force-displacement spectroscopy. In Appendix B a brief description of work done to grow isolated nanowires of Cu:TCNQ, between two metal electrodes in planar geometry and in anodic alumina membranes is given.

This diploma thesis deals with the microbial production of biosurfactants of selected bacterial strains. In order to test the biosurfactant production ability, screening methods were chosen to be able to review the potential of the selected strains to produce biosurfactants. With the scope of the work, 11 bacterial strains, which are used as polyhydroxyalkanoate (PHA) producers, have been tested. The ability to produce biosurfactants was tested in all strains both in complex inoculation and mineral production media. The presence of biosurfactants in Pseudomonas putida was detected on the basis of the results obtained after cultivation in inoculation and production media. The bacteria Pseudomonas fulva was put under more deep study to support their production by cultivation in different types of production media supplemented by different sources of carbon and nitrogen, and the effect of cultivation time was tested as well. Biosurfactants produced by these bacteria were subsequently identified by Fourier transform infrared spectroscopy (FTIR) on the basis of which the substances were identified as rhamnolipids. According to thin-layer chromatography result (TLC), Pseudomonas putida produces a mixture of mono- and dirhamnolipids, with monorhamnolipids being more dominant in our samples.