Made available in DSpace on 2015-04-17T14:49:11Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1274751 bytes, checksum: 6c827954d80bb78ad96eb49019db7241 (MD5) Previous issue date: 2011-05-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Sun meat is a widely accepted foodstuff in the Brazilian northeast, with processing generally carried out by hand by small producers who, due to the absence of specific legislation, show differences in their acquisition processes, which influences the final quality with considerable variation in its physical-chemical, microbiological and sensory aspects. This study aimed to characterize the sun meat processing commercialized in the municipality of João Pessoa/PB through structured interviews with shopkeepers and producers and to evaluate the physical-chemical, microbiological and sensory characteristics of sun meat processed with previously matured raw material compared to sun meat commercialized in the municipality of João Pessoa/PB. Three sun meat samples were evaluated, with two being processed at pilot scale, differentiated by the previous treatment of the raw material, one being traditional and the other having matured previously during 14 days. The samples were processed using the commercial cut inside round (m. semimenbranosus e m. adductor femoris), following the processing stages (preparation of the raw material, salting, washing, drying and refrigeration) in accordance with the survey carried out among the producers of the city of João Pessoa/PB. The processed samples were compared with a commercial sample from the city of João Pessoa/PB, which were evaluated in relation to its physical-chemical quality: composition, centesimal composition, chlorates, water activity (Aa), pH, water retention capacity (CRA), color (L*, a*, b*) and shear force with a Warner-Bratzler blade, microbiological analysis (total coliforms and thermotolerant bacteria, Salmonella sp e Estafilococos coagulase positiva) and sensory analysis, by trained panelists, and, acceptance by potential consumers. 79 shopkeepers were interviewed in 15 visited establishments of which, 31,6% process their own sun meat they commercialize, and the slaughterhouses operation was checked (39,2%) regarding the supply of sun meat commercialized in these establishments. A similarity in the processing techniques of processed sun meat was observed for both small producers and slaughterhouses, however, a lack of standardization of operations was found in relation to the type and salting time and the way in which drying was realized in the sun meat processing. The maturing process did not influence the physical-chemical, nor the microbiological quality of the sun meat, not being different from the traditional, nor the commercial sun meat. However, the addition of sodium chlorate and the salting time of the present study were sufficient to reduce the humidity and to increase the chlorate concentrations of the products, but these variations were not sufficient to reduce the Aa, no difference was observed (p≥ 0,05) between the raw material and the products. However, low content of chlorates between 2,49 and 4,66, elevated. Aa between 0,94 and 0,95 and pH between 5,8 and 6,1 show the high perishability of the product, which should have double attention for the use of good practices during its processing, using matured raw material. The maturing process also did not influence the sensory quality of the sun meat, not having any difference (p≥ 0,05), according to both the trained panelists and the acceptance test, where the three samples obtained an acceptance rate of over 60%. The maturing process did not produce the expected effects. Therefore, further study with longer maturing times, and, or, new techniques with the intent of providing even greater tenderness of the sun meat, is recommended. / A carne-de-sol é um alimento de ampla aceitação no Nordeste brasileiro, com processamento, na grande maioria, realizado artesanalmente por pequenos produtores que devido à ausência de legislação específica, apresentam variações no seu processo de obtenção, influenciando na sua qualidade final. Objetivou-se neste trabalho caracterizar o processamento da carne-de-sol comercializada no município de João Pessoa/PB, por meio de entrevista estruturada junto aos comerciantes e produtores, e avaliar as características físico-químicas, microbiológicas e sensoriais da carne-de-sol processada com matéria-prima previamente maturada comparada com carne-de-sol comercial do município de João Pessoa/PB. Foram avaliadas três amostras de carne-de-sol, sendo duas processadas em escala piloto, diferenciadas pelo tratamento prévio da matéria-prima, sendo uma tradicional e a outra previamente maturada por 14 dias. As amostras foram processadas usando o corte comercial coxão mole (m. semimenbranosus e m. adductor femoris), seguindo as etapas de processamento (preparação da matéria-prima, salga, lavagem, secagem e refrigeração) de acordo com o levantamento realizado junto aos produtores da cidade de João Pessoa/PB. As amostras processadas foram comparadas com uma amostra comercial da cidade de João Pessoa/PB, que foram avaliadas quanto à qualidade físico-química: composição centesimal, cloretos, atividade de água (Aa), pH, capacidade de retenção de água (CRA), cor (L*, a*, b*) e força de cisalhamento; análise microbiológica (coliformes totais e termotolerantes, Salmonella sp e Estafilococos coagulase positiva) e análise sensorial, por provadores treinados e, aceitação por potenciais consumidores.Verificou-se que 31,6% dos comerciantes processam a própria carne-de-sol que comercializam; 16,5% são provenientes de pequenos produtores e 39,2% de frigoríficos. Não foram observadas variações nas técnicas de processamento entre os pequenos produtores e os frigoríficos, no entanto, verificou-se a falta de padronização entre as operações em relação ao tipo e tempo de salga e a forma de secagem realizada no processamento das carnes-de-sol. O processo de maturação não influenciou na qualidade físico-química e microbiológica da carne-de-sol, não diferenciando da carne-de-sol tradicional, nem da comercial. A adição de cloreto de sódio e o tempo de salga do presente estudo foram suficientes para reduzir a umidade e aumentar as concentrações de cloretos dos produtos, porém, estas variações não foram suficientes para reduzir a Aa, não sendo observada diferença (p ≥ 0,05) entre as matérias-primas e os produtos. O processo de maturação também não influenciou na qualidade sensorial da carne-de-sol, não havendo diferença (p ≥ 0,05) tanto pelo painel treinado quanto pelo teste de aceitação, onde as três amostras obtiveram aceitação superior a 60%. O processo de maturação não surtiu o efeito esperado, recomendando-se novos estudos com maior tempo de maturação e, ou, novas técnicas com o intuito de proporcionar uma maior maciez da carne-de-sol.

Ever since their discovery in 1991, carbon nanotubes are of great interest to the scientific community due to their outstanding optical, mechanical and electrical properties. Considering their impressive properties, as for instance the high current carrying capability and the possibility of ballistic charge transport, carbon nanotubes are a desired channel material in field-effect transistors, especially with respect to high frequency communication electronics. Thus, many scientific studies on CNT-based field-effect transistors have been published so far. But despite the successful verification of excellent individual electric key values, corresponding experiments are mostly performed under synthetic conditions (considering e.g. temperature or gas atmosphere), which are not realizable during realistic application scenarios. Furthermore, technologically relevant factors like homogeneity, reproducibility and yield of functioning devices are often subordinated to the achievement of a single electric record value. Hence, this work focuses on the development of a fabrication technology for carbon nanotube field-effect transistors, that takes those factors into account. Thereby, this work expands the state of the art by introduction and statistical assessment of two cleaning processes: a) wet chemical removal of surfactant residues (sodium dodecylsulfate) from CNTs, integrated using the dielectrophoretic approach, by investigation and comparison of four procedures (de-ionized water, HNO3, oDCB, Ethanol); b) the reduction of process-related substrate contaminations by application of an oxygen plasma. Beyond that, the passivation of the final, working devices is developed further, as their typical definition as diffusion barrier is expanded by the reduction of parasitic capacitances in the transistor. In this context, two so far barely considered materials, hydrogen silsesquioxane and Xdi-dcs, a polymer mixture of poly(vinylphenol) and polymethylsilsesquioxane, are investigated and assessed. The novelty of the Xdi-dcs mixture causes the necessity of fundamental considerations on controllable etching procedures and resulting adaptions of the technological fabrication sequence.:Bibliographic description 3 List of abbreviations 10 List of symbols 10 1 Introduction 13 2 Basics of carbon nanotubes 15 2.1 Structural fundamentals 15 2.1.1 Hybridization of carbon 15 2.1.2 Structure of carbon nanotubes 17 2.2 Electronic properties 19 2.2.1 Band structure of graphene 19 2.2.2 Band structure of carbon nanotubes 20 2.2.3 Electronic transport in CNTs 22 2.3 Procedures for CNT integration 23 2.3.1 Growth by chemical vapor deposition 24 2.3.2 Transfer techniques 24 2.3.3 Dispersion-related integration procedures 25 2.4 Interaction of CNT and surfactant 28 3 Basics of CNT field-effect transistors 31 3.1 Principle of operation of conventional FETs 31 3.2 Distinctive features of CNT-based FETs 32 3.2.1 Metal - semiconductor contact 33 3.2.2 Linearity 38 3.3 Performance determining factors 41 3.3.1 Device architecture 41 3.3.2 Contact geometry 46 3.3.3 Other transistor dimensions 48 3.3.4 CNT-related characteristics 49 3.4 Hysteresis in transfer characteristics 51 3.4.1 Definition of hysteresis 51 3.4.2 Origins of hysteresis 52 3.4.3 Appearance of hysteresis 53 3.5 Passivation 56 3.5.1 Requirements 56 3.5.2 Importance of pre-treatments and process conditions 57 3.5.3 Overview of established passivation materials 58 4 Experimental work 63 4.1 Transistor design 63 4.2 Technology flow 66 4.3 Experimental procedures 71 4.3.1 Procedures for dissolution of SDS 71 4.3.2 Plasma treatment against surface contaminations 72 4.3.3 Evaluation of diffusion barriers 72 4.4 Instrumentation and characterization 74 4.4.1 Dielectrophoresis instrumentation 74 4.4.2 Topographical Characterization 74 4.4.3 Chemical characterization 75 4.4.4 Electrical characterization 76 5 Reduction of hysteresis 77 5.1 Removal of surfactant molecules from CNTs 77 5.1.1 Influence on molecule and CNT chemistry 78 5.1.2 Effect on transistor performance 80 5.2 Plasma-assisted removal of substrate contaminations 87 5.2.1 Influence on substrate surface 88 5.2.2 Effect on transistor performance 92 6 Passivation 97 6.1 Protection against environmental effects 97 6.1.1 Alterability of unpassivated CNT-FETs 98 6.1.2 Effects of O2 exclusion by dense passivation 99 6.1.3 Intentional doping using Y2O3 101 6.2 Passivation considering electrostatic aspects 106 6.2.1 Integration of Xdi-dcs as novel passivation 107 6.2.2 Comparison of two spin-coated dielectrics 111 6.3 Potential of double-layer approaches 113 6.3.1 Evaluation of the gas barrier performance 113 6.3.2 Influence on the transistor behavior 116 7 Summary and Outlook 121 Danksagung 127 Appendix 129 Bibliography 137 List of figures 156 List of tables 161 Selbstständigkeitserklärung 163 8 Thesen 165 9 Curriculum vitae 169 / Bereits seit ihrer Entdeckung 1991 sind Kohlenstoffnanoröhren, aufgrund ihrer herausragenden optischen, mechanischen und elektrischen Eigenschaften, für die wissenschaftliche Community von großem Interesse. Ihre Verwendung als Kanalmaterial in Feld-Effekt Transistoren ist in Anbetracht ihrer außergewöhnlichen Eigenschaften, wie z. B. die hohe Stromtragfähigkeit, sowie die Möglichkeit des ballistischen Transports von Ladungsträgern besonders für die hochfrequente Kommunikationselektronik erstrebenswert. Dementsprechend viele wissenschaftliche Arbeiten befassen sich mit der Erforschung von auf Kohlenstoffnanoröhren basierenden Transistoren. Doch trotz des erfolgreichen Nachweises ausgezeichneter Werte für viele individuelle elektrische Kenngrößen, finden entsprechenden Experimente zumeist unter anwendungsfernen Bedingungen bezüglich Temperatur bzw. Gasatmosphäre statt. Darüber hinaus werden dem Erreichen eines elektrischen Rekordwertes oft technologisch relevante Größen wie Homogenität, Reproduzierbarkeit und Ausbeute an funktionsfähigen Bauteilen untergeordnet. Der Fokus dieser Arbeit liegt daher auf der Erarbeitung einer Technologie zur Herstellung Kohlenstoffnanoröhrenbasierter Feld-Effekt Transistoren, unter Berücksichtigung dieser Aspekte. Dabei erweitert diese Arbeit den Stand der Technik durch die Einführung und statistische Beurteilung zweier Reinigungsprozesse: a) der nasschemischen Beseitigung von Tensidresten (Natriumdodecylsulfat) an mittels Dielektrophorese integrierten CNTs, wobei insgesamt vier Prozeduren (de-ionisiertes Wasser, HNO3, oDCB, Ethanol) betrachtet und miteinander verglichen wurden; b) der Beseitigung von prozessbedingten Substratkontaminationen durch ein Sauerstoffplasma. Darüber hinaus wird die Passivierung der funktionsfähigen Bauelemente weiterentwickelt, indem ihre typische Definition als Diffusionsbarriere um den Aspekt der Verringerung parasitärer Kapazitäten im Transistor erweitert wird. In diesem Zusammenhang werden mit Wasserstoff-Silsesquioxane und Xdi-dcs, einem Polymergemisch aus Poly(vinylphenol) und Polymethylsilsesquioxane, zwei bislang wenig beachtete Materialien, untersucht und bewertet. Die Neuheit des Xdi-dcs Gemisches macht dabei fundamentale Untersuchungen zur Strukturierbarkeit und entsprechende technologische Anpassungen im Gesamtablauf nötig.:Bibliographic description 3 List of abbreviations 10 List of symbols 10 1 Introduction 13 2 Basics of carbon nanotubes 15 2.1 Structural fundamentals 15 2.1.1 Hybridization of carbon 15 2.1.2 Structure of carbon nanotubes 17 2.2 Electronic properties 19 2.2.1 Band structure of graphene 19 2.2.2 Band structure of carbon nanotubes 20 2.2.3 Electronic transport in CNTs 22 2.3 Procedures for CNT integration 23 2.3.1 Growth by chemical vapor deposition 24 2.3.2 Transfer techniques 24 2.3.3 Dispersion-related integration procedures 25 2.4 Interaction of CNT and surfactant 28 3 Basics of CNT field-effect transistors 31 3.1 Principle of operation of conventional FETs 31 3.2 Distinctive features of CNT-based FETs 32 3.2.1 Metal - semiconductor contact 33 3.2.2 Linearity 38 3.3 Performance determining factors 41 3.3.1 Device architecture 41 3.3.2 Contact geometry 46 3.3.3 Other transistor dimensions 48 3.3.4 CNT-related characteristics 49 3.4 Hysteresis in transfer characteristics 51 3.4.1 Definition of hysteresis 51 3.4.2 Origins of hysteresis 52 3.4.3 Appearance of hysteresis 53 3.5 Passivation 56 3.5.1 Requirements 56 3.5.2 Importance of pre-treatments and process conditions 57 3.5.3 Overview of established passivation materials 58 4 Experimental work 63 4.1 Transistor design 63 4.2 Technology flow 66 4.3 Experimental procedures 71 4.3.1 Procedures for dissolution of SDS 71 4.3.2 Plasma treatment against surface contaminations 72 4.3.3 Evaluation of diffusion barriers 72 4.4 Instrumentation and characterization 74 4.4.1 Dielectrophoresis instrumentation 74 4.4.2 Topographical Characterization 74 4.4.3 Chemical characterization 75 4.4.4 Electrical characterization 76 5 Reduction of hysteresis 77 5.1 Removal of surfactant molecules from CNTs 77 5.1.1 Influence on molecule and CNT chemistry 78 5.1.2 Effect on transistor performance 80 5.2 Plasma-assisted removal of substrate contaminations 87 5.2.1 Influence on substrate surface 88 5.2.2 Effect on transistor performance 92 6 Passivation 97 6.1 Protection against environmental effects 97 6.1.1 Alterability of unpassivated CNT-FETs 98 6.1.2 Effects of O2 exclusion by dense passivation 99 6.1.3 Intentional doping using Y2O3 101 6.2 Passivation considering electrostatic aspects 106 6.2.1 Integration of Xdi-dcs as novel passivation 107 6.2.2 Comparison of two spin-coated dielectrics 111 6.3 Potential of double-layer approaches 113 6.3.1 Evaluation of the gas barrier performance 113 6.3.2 Influence on the transistor behavior 116 7 Summary and Outlook 121 Danksagung 127 Appendix 129 Bibliography 137 List of figures 156 List of tables 161 Selbstständigkeitserklärung 163 8 Thesen 165 9 Curriculum vitae 169