Torneamento da liga de alumínio da classe 6005 utilizando ferramenta cerâmica

Machining processes are one of the most important manufacturing processes in the modern world. In these processes, there are many elements which will influence in the final result of the machined part. Among them, the tools are the principal factor of the rising cost, because its global influence on the process. In aeronautical industries, this can be more evidenced due the need to machining several alloys, between them, aluminum alloys. These alloys have to demonstrate a specific surface finishing to be used in aircraft's fuselage. This kind of industry is one of the segments which is still rising in Brazil, and they are looking viable alternatives in the manufacturing processes of materials, due the need to produce more and more parts and equipment, with costs increasingly reduced. The purpose of this project is the development of a ceramic with differentiated properties. The ceramics were developed using a pre-sintering at 1200 °C, with posterior sintering at 1600°C, and subjected to dry turning process on aluminum alloy 6005. The characterizations showed that ceramics presented with toughness on the center of 1700 MPa and on the surface of 1950 MPa, density 98,5 ±0,14. g/cm³. Ceramics were grinded and faceted, according to ISO standard 1832, and subjected to turning tests in a ROMI lathe brand, model GL240M, using cutting speeds of 500, 800 and 1000 m/min with different feed rates. The machining results showed low occurrence of flank wear to all cutting speeds, and better surface finishing average values of Ra = 0,4935 μm and Rt = 8,112 μm. In general, it could be seen that the tool presents important potential to machining 6005 alloy, and that the use of correct parameters can decrease and/or eliminate subsequent processes, providing important reductions in costs related to the machining processes

Influência da inalação da fumaça de cigarro na regeneração óssea guiada em enxertos autógenos onlay em ratas com deficiência estrogênica: estudo histomorfométrico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produção do Espaço Urbano e Dinâmica Imobiliária em Cidades Médias: os casos de Presidente Prudente (SP), São José do Rio Preto (SP) e Lleida (ESP)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Torneamento da liga de alumínio da classe 6005 utilizando ferramenta cerâmica

Machining processes are one of the most important manufacturing processes in the modern world. In these processes, there are many elements which will influence in the final result of the machined part. Among them, the tools are the principal factor of the rising cost, because its global influence on the process. In aeronautical industries, this can be more evidenced due the need to machining several alloys, between them, aluminum alloys. These alloys have to demonstrate a specific surface finishing to be used in aircraft's fuselage. This kind of industry is one of the segments which is still rising in Brazil, and they are looking viable alternatives in the manufacturing processes of materials, due the need to produce more and more parts and equipment, with costs increasingly reduced. The purpose of this project is the development of a ceramic with differentiated properties. The ceramics were developed using a pre-sintering at 1200 °C, with posterior sintering at 1600°C, and subjected to dry turning process on aluminum alloy 6005. The characterizations showed that ceramics presented with toughness on the center of 1700 MPa and on the surface of 1950 MPa, density 98,5 ±0,14. g/cm³. Ceramics were grinded and faceted, according to ISO standard 1832, and subjected to turning tests in a ROMI lathe brand, model GL240M, using cutting speeds of 500, 800 and 1000 m/min with different feed rates. The machining results showed low occurrence of flank wear to all cutting speeds, and better surface finishing average values of Ra = 0,4935 μm and Rt = 8,112 μm. In general, it could be seen that the tool presents important potential to machining 6005 alloy, and that the use of correct parameters can decrease and/or eliminate subsequent processes, providing important reductions in costs related to the machining processes

Habitat structure and food resources for wildlife across successional stages in a tropical forest

Tropical forests are experiencing an increase in the proportion of secondary forests as a result of the balance between the widespread harvesting of old-growth forests and the regeneration in abandoned areas. The impacts of such a process on biodiversity are poorly known and intensely debated. Recent reviews and multi-taxa studies indicate that species replacement in wildlife assemblages is a consistent pattern, sometimes stronger than changes in diversity, with a replacement from habitat generalists to old-growth specialists being commonly observed during tropical forest regeneration. However, the ecological drivers of such compositional changes are rarely investigated, despite its importance in assessing the conservation value of secondary forests, and to support and guide management techniques for restoration. By sampling 28 sites in a continuous Atlantic forest area in Southeastern Brazil, we assessed how important aspects of habitat structure and food resources for wildlife change across successional stages, and point out hypotheses on the implications of these changes for wildlife recovery. Old-growth areas presented a more complex structure at ground level (deeper leaf litter, and higher woody debris volume) and higher fruit availability from an understorey palm, whereas vegetation connectivity, ground-dwelling arthropod biomass, and total fruit availability were higher in earlier successional stages. From these results we hypothetize that generalist species adapted to fast population growth in resource-rich environments should proliferate and dominate earlier successional stages, while species with higher competitive ability in resource-limited environments, or those that depend on resources such as palm fruits, on higher complexity at the ground level, or on open space for flying, should dominate older-growth forests. Since the identification of the drivers of wildlife recovery is crucial for restoration strategies, it is important that future work test and further develop the proposed hypotheses. We also found structural and functional differences between old-growth forests and secondary forests with more than 80 years of regeneration, suggesting that restoration strategies may be crucial to recover structural and functional aspects expected to be important for wildlife in much altered ecosystems, such as the Brazilian Atlantic forest. (C) 2012 Elsevier B.V. All rights reserved.

Escrubagem da bauxita de Paragominas - PA. Parte 1: influência de variáveis operacionais na desagregação da bauxita

The aim of this study was to investigate the bauxite scrubbing process on samples from Miltonia 3, a Vale operation in the State of Para, Brazil. The experimental program included the design of a standard laboratory test, from which parameters were derived for predicting the operation of a scrubber in steady state conditions. Three main variables were selected for the laboratory experimental program using the factorial design technique. These were load fraction, residence time and rotation speed. The amount of fines was determined through screening both the feed and the product of the scrubbing test. The former was considered to be a characteristic material, while the second was the dependent variable, i.e. the result of the scrubbing process. According to experiments, the load fraction was the most important variable for the scrubbing process.

Microstructured ternary solid dispersions to improve carbamazepine solubility

The aim of this study was to investigate the improvement of the aqueous solubility of carbamazepine by preparing microstructured ternary solid dispersions using polyoxylglycerides and colloidal silicon dioxide. Microstructured solid dispersions were obtained in a spray dryer. The influence of the spray drying conditions on the properties of the microparticles was investigated using a full 3(2) factorial design in which the factors studied were the silicon dioxide content and the air outlet temperature. The microparticles were thoroughly characterized in terms of yield, solubility, angle of repose, particle size, drug content, moisture content, sorption isotherms, morphology, thermal behavior, infrared spectroscopy and crystallinity. The dissolution rates of carbamazepine and of the microparticles in water were also determined. In general, the microstructured solid dispersions demonstrated good yield, adequate flow and moisture content (<3%), drug recovery (91.98 to 100.22%) and particle size (<142.90 mu m). Thermal and infrared analysis showed that there was no drug interaction during the process. On the other hand, the results of X-ray diffraction evidenced a partial polymorphic modification of carbamazepine. The solubility and dissolution rates of carbamazepine were remarkably improved. Therefore, the results confirm the high potential of the spray drying technique to obtain microstructured ternary solid dispersions. (C) 2011 Elsevier B.V. All rights reserved.

Processi di biorefining per l'estrazione di secondary chemical building blocks da sottoprotti dell'agro-industria

Phenol and cresols represent a good example of primary chemical building blocks of which 2.8 million tons are currently produced in Europe each year. Currently, these primary phenolic building blocks are produced by refining processes from fossil hydrocarbons: 5% of the world-wide production comes from coal (which contains 0.2% of phenols) through the distillation of the tar residue after the production of coke, while 95% of current world production of phenol is produced by the distillation and cracking of crude oil. In nature phenolic compounds are present in terrestrial higher plants and ferns in several different chemical structures while they are essentially absent in lower organisms and in animals. Biomass (which contain 3-8% of phenols) represents a substantial source of secondary chemical building blocks presently underexploited. These phenolic derivatives are currently used in tens thousand of tons to produce high cost products such as food additives and flavours (i.e. vanillin), fine chemicals (i.e. non-steroidal anti-inflammatory drugs such as ibuprofen or flurbiprofen) and polymers (i.e. poly p-vinylphenol, a photosensitive polymer for electronic and optoelectronic applications). European agrifood waste represents a low cost abundant raw material (250 millions tons per year) which does not subtract land use and processing resources from necessary sustainable food production. The class of phenolic compounds is essentially constituted by simple phenols, phenolic acids, hydroxycinnamic acid derivatives, flavonoids and lignans. As in the case of coke production, the removal of the phenolic contents from biomass upgrades also the residual biomass. Focusing on the phenolic component of agrifood wastes, huge processing and marketing opportunities open since phenols are used as chemical intermediates for a large number of applications, ranging from pharmaceuticals, agricultural chemicals, food ingredients etc. Following this approach we developed a biorefining process to recover the phenolic fraction of wheat bran based on enzymatic commercial biocatalysts in completely water based process, and polymeric resins with the aim of substituting secondary chemical building blocks with the same compounds naturally present in biomass. We characterized several industrial enzymatic product for their ability to hydrolize the different molecular features that are present in wheat bran cell walls structures, focusing on the hydrolysis of polysaccharidic chains and phenolics cross links. This industrial biocatalysts were tested on wheat bran and the optimized process allowed to liquefy up to the 60 % of the treated matter. The enzymatic treatment was also able to solubilise up to the 30 % of the alkali extractable ferulic acid. An extraction process of the phenolic fraction of the hydrolyzed wheat bran based on an adsorbtion/desorption process on styrene-polyvinyl benzene weak cation-exchange resin Amberlite IRA 95 was developed. The efficiency of the resin was tested on different model system containing ferulic acid and the adsorption and desorption working parameters optimized for the crude enzymatic hydrolyzed wheat bran. The extraction process developed had an overall yield of the 82% and allowed to obtain concentrated extracts containing up to 3000 ppm of ferulic acid. The crude enzymatic hydrolyzed wheat bran and the concentrated extract were finally used as substrate in a bioconversion process of ferulic acid into vanillin through resting cells fermentation. The bioconversion process had a yields in vanillin of 60-70% within 5-6 hours of fermentation. Our findings are the first step on the way to demonstrating the economical feasibility for the recovery of biophenols from agrifood wastes through a whole crop approach in a sustainable biorefining process.

Teaching and learning english phonetics and phonology in the EHEA through design and creation of audiovisual material at the ULPGC

[ES]In this paper we describe the procedure followed in the design and recording of a set of videos for teaching and learning ‘English phonetics and phonology’, a second-year undergraduate course at Universidad de Las Palmas de Gran Canaria. The student’s L1 is Spanish. Two different types of technological support were used: screencast and Powerpoint® presentations. The traditional whiteboard together with the lecturer’s presence also contributed both to the integrated learning of certain acoustic/articulatory aspects of the course contents and to the use of specific software for speech analysis. This video production owns the advantage of being an interactive and autonomous tool which favours a continuous learning process on the student’s side.

Studio di fenomeni d'instabilità gravitativa sui fondali marini, con particolare riferimento all'isola di Stromboli

In the last decade the interest for submarine instability grew up, driven by the increasing exploitation of natural resources (primary hydrocarbons), the emplacement of bottom-lying structures (cables and pipelines) and by the development of coastal areas, whose infrastructures increasingly protrude to the sea. The great interest for this topic promoted a number of international projects such as: STEAM (Sediment Transport on European Atlantic Margins, 93-96), ENAM II (European North Atlantic Margin, 96-99), GITEC (Genesis and Impact of Tsunamis on the European Coast 92-95), STRATAFORM (STRATA FORmation on Margins, 95-01), Seabed Slope Process in Deep Water Continental Margin (Northwest Gulf of Mexico, 96-04), COSTA (Continental slope Stability, 00-05), EUROMARGINS (Slope Stability on Europe’s Passive Continental Margin), SPACOMA (04-07), EUROSTRATAFORM (European Margin Strata Formation), NGI's internal project SIP-8 (Offshore Geohazards), IGCP-511: Submarine Mass Movements and Their Consequences (05-09) and projects indirectly related to instability processes, such as TRANSFER (Tsunami Risk ANd Strategies For the European region, 06-09) or NEAREST (integrated observations from NEAR shore sourcES of Tsunamis: towards an early warning system, 06-09). In Italy, apart from a national project realized within the activities of the National Group of Volcanology during the framework 2000-2003 “Conoscenza delle parti sommerse dei vulcani italiani e valutazione del potenziale rischio vulcanico”, the study of submarine mass-movement has been underestimated until the occurrence of the landslide-tsunami events that affected Stromboli on December 30, 2002. This event made the Italian Institutions and the scientific community more aware of the hazard related to submarine landslides, mainly in light of the growing anthropization of coastal sectors, that increases the vulnerability of these areas to the consequences of such processes. In this regard, two important national projects have been recently funded in order to study coastal instabilities (PRIN 24, 06-08) and to map the main submarine hazard features on continental shelves and upper slopes around the most part of Italian coast (MaGIC Project). The study realized in this Thesis is addressed to the understanding of these processes, with particular reference to Stromboli submerged flanks. These latter represent a natural laboratory in this regard, as several kind of instability phenomena are present on the submerged flanks, affecting about 90% of the entire submerged areal and often (strongly) influencing the morphological evolution of subaerial slopes, as witnessed by the event occurred on 30 December 2002. Furthermore, each phenomenon is characterized by different pre-failure, failure and post-failure mechanisms, ranging from rock-falls, to turbidity currents up to catastrophic sector collapses. The Thesis is divided into three introductive chapters, regarding a brief review of submarine instability phenomena and related hazard (cap. 1), a “bird’s-eye” view on methodologies and available dataset (cap. 2) and a short introduction on the evolution and the morpho-structural setting of the Stromboli edifice (cap. 3). This latter seems to play a major role in the development of largescale sector collapses at Stromboli, as they occurred perpendicular to the orientation of the main volcanic rift axis (oriented in NE-SW direction). The characterization of these events and their relationships with successive erosive-depositional processes represents the main focus of cap.4 (Offshore evidence of large-scale lateral collapses on the eastern flank of Stromboli, Italy, due to structurally-controlled, bilateral flank instability) and cap. 5 (Lateral collapses and active sedimentary processes on the North-western flank of Stromboli Volcano), represented by articles accepted for publication on international papers (Marine Geology). Moreover, these studies highlight the hazard related to these catastrophic events; several calamities (with more than 40000 casualties only in the last two century) have been, in fact, the direct or indirect result of landslides affecting volcanic flanks, as observed at Oshima-Oshima (1741) and Unzen Volcano (1792) in Japan (Satake&Kato, 2001; Brantley&Scott, 1993), Krakatau (1883) in Indonesia (Self&Rampino, 1981), Ritter Island (1888), Sissano in Papua New Guinea (Ward& Day, 2003; Johnson, 1987; Tappin et al., 2001) and Mt St. Augustine (1883) in Alaska (Beget& Kienle, 1992). Flank landslide are also recognized as the most important and efficient mass-wasting process on volcanoes, contributing to the development of the edifices by widening their base and to the growth of a volcaniclastic apron at the foot of a volcano; a number of small and medium-scale erosive processes are also responsible for the carving of Stromboli submarine flanks and the transport of debris towards the deeper areas. The characterization of features associated to these processes is the main focus of cap. 6; it is also important to highlight that some small-scale events are able to create damage to coastal areas, as also witnessed by recent events of Gioia Tauro 1978, Nizza, 1979 and Stromboli 2002. The hazard potential related to these phenomena is, in fact, very high, as they commonly occur at higher frequency with respect to large-scale collapses, therefore being more significant in terms of human timescales. In the last chapter (cap. 7), a brief review and discussion of instability processes identified on Stromboli submerged flanks is presented; they are also compared with respect to analogous processes recognized in other submerged areas in order to shed lights on the main factors involved in their development. Finally, some applications of multibeam data to assess the hazard related to these phenomena are also discussed.

Molecular characterization of the human gut microbiota: the effect of aging

Age-related physiological changes in the gastrointestinal tract, as well as modification in lifestyle, nutritional behaviour, and functionality of the host immune system, inevitably affect the gut microbiota. The study presented here is focused on the application and comparison of two different microarray approaches for the characterization of the human gut microbiota, the HITChip and the HTF-Microb.Array, with particular attention to the effects of the aging process on the composition of this ecosystem. By using the Human Intestinal Tract Chip (HITChip), recently developed at the Wageningen University, The Netherland, we explored the age-related changes of gut microbiota during the whole adult lifespan, from young adults, through elderly to centenarians. We observed that the microbial composition and diversity of the gut ecosystem of young adults and seventy-years old people is highly similar but differs significantly from that of the centenarians. After 100 years of symbiotic association with the human host, the microbiota is characterized by a rearrangement in the Firmicutes population and an enrichment of facultative anaerobes. The presence of such a compromised microbiota in the centenarians is associated with an increased inflammation status, also known as inflamm-aging, as determined by a range of peripheral blood inflammatory markers. In parallel, we overtook the development of our own phylogenetic microarray with a lower number of targets, aiming the description of the human gut microbiota structure at high taxonomic level. The resulting chip was called High Taxonomic level Fingerprinting Microbiota Array (HTF-Microb.Array), and was based on the Ligase Detection Reaction (LDR) technology, which allowed us to develop a fast and sensitive tool for the fingerprint of the human gut microbiota in terms of presence/absence of the principal groups. The validation on artificial DNA mixes, as well as the pilot study involving eight healthy young adults, demonstrated that the HTF-Microb.Array can be used to successfully characterize the human gut microbiota, allowing us to obtain results which are in approximate accordance with the most recent characterizations. Conversely, the evaluation of the relative abundance of the target groups on the bases of the relative fluorescence intensity probes response still has some hindrances, as demonstrated by comparing the HTF.Microb.Array and HITChip high taxonomic level fingerprints of the same centenarians.

Untersuchung der Filmbildung aus Polymerdispersionen mit Hilfe der forcierten Rayleighstreuung

Der Filmbildungsprozess wässriger Polymerdispersionen wurde mit forcierter Rayleighstreuung untersucht.Diffusionskoeffizienten D von Farbstoffsonden sind damit zwischen 10^-21 und 10^-9 m^2s^-1 zugänglich. Das Diffusionsverhalten der hydrophoben FarbstoffsondeAberchrome in feuchten und trockenen Filmen aus Poly(n-butylmethacrylat-co-acrylsäure)-Dispersionen sowie bei der Wiederbefeuchtung trockener Filme wurde untersucht.Die Dynamik von Aberchrome weicht in feuchten Filmen von Fickscher Diffusion ab. Dies äußert sich in Abweichungen vomcharakteristischen q^2-Verhalten der Relaxationsrate tau^-1 (tau^-1 = Dq^2; q:Streuvektor) und im Auftreten gestrecktexponentieller Intensitätsrelaxationskurven. Diese Anomalie wurde mit einem apparenten, längenskalenabhängigen Diffusionskoeffizienten Dapp(Lambda) (Lambda= 2Pi/q) beschrieben, der für Lambda -> 0 Werte annimmt, die einem homogen hydroplastifizierten Polymermaterial entsprechen, während Dapp(Lambda) für Lambda -> Unendlich stark anwächst. Diese Anomalien verschwinden bei Wassergehalten entsprechend der Polymerwasserlöslichkeit. Weiteres Trocknen führt zum Absinken des Fickschen-Diffusionskoeffizienten auf einen Grenzwert für trockene Filme. Die Ergebnisse konnten mit einem Zwei-Zustands-Modell beschrieben werden: Die Sonde diffundiert Ficksch in einer hydrophilen Grenzflächenphase und einer langsamen Polymerphase. Austausch zwischendiesen Phasen ist ohne Einschränkung möglich. Das Modell erlaubt die Quantifizierung des Einflusses des Trocknungsprozesses auf Polymer- und Grenzflächenphaseneigenschaften.Dies wurde durch systematische Veränderungen der Grenzflächeneigenschaften demonstriert. Dies geschah durch Acrylsäuregehaltvariationen in den Poly(n-butylmethacrylat-co-acrylsäure)-Dispersionen und Emulgatorbedeckungsgradvariationen. In beiden Fällen reflektieren sich Dispersionsveränderungen in einer Veränderung der Modellparameter in der Grenzflächenphase.

Design, implementation and evaluation of a virtual laboratory for Computer Engineering Education

Broad consensus has been reached within the Education and Cognitive Psychology research communities on the need to center the learning process on experimentation and concrete application of knowledge, rather than on a bare transfer of notions. Several advantages arise from this educational approach, ranging from the reinforce of students learning, to the increased opportunity for a student to gain greater insight into the studied topics, up to the possibility for learners to acquire practical skills and long-lasting proficiency. This is especially true in Engineering education, where integrating conceptual knowledge and practical skills assumes a strategic importance. In this scenario, learners are called to play a primary role. They are actively involved in the construction of their own knowledge, instead of passively receiving it. As a result, traditional, teacher-centered learning environments should be replaced by novel learner-centered solutions. Information and Communication Technologies enable the development of innovative solutions that provide suitable answers to the need for the availability of experimentation supports in educational context. Virtual Laboratories, Adaptive Web-Based Educational Systems and Computer-Supported Collaborative Learning environments can significantly foster different learner-centered instructional strategies, offering the opportunity to enhance personalization, individualization and cooperation. More specifically, they allow students to explore different kinds of materials, to access and compare several information sources, to face real or realistic problems and to work on authentic and multi-facet case studies. In addition, they encourage cooperation among peers and provide support through coached and scaffolded activities aimed at fostering reflection and meta-cognitive reasoning. This dissertation will guide readers within this research field, presenting both the theoretical and applicative results of a research aimed at designing an open, flexible, learner-centered virtual lab for supporting students in learning Information Security.

I materiali ceramici trasparenti: preparazione, caratterizzazione e correlazione microstruttura-proprietà

This thesis focuses on the ceramic process for the production of optical grade transparent materials to be used as laser hosts. In order to be transparent a ceramic material must exhibit a very low concentration of defects. Defects are mainly represented by secondary or grain boundary phases and by residual pores. The strict control of the stoichiometry is mandatory to avoid the formation of secondary phases, whereas residual pores need to be below 150 ppm. In order to fulfill these requirements specific experimental conditions must be combined together. In addition powders need to be nanometric or at least sub-micrometric and extremely pure. On the other hand, nanometric powders aggregate easily and this leads to a poor, not homogeneous packing during shaping by pressing and to the formation of residual pores during sintering. Very fine powders are also difficult to handle and tend to absorb water on the surface. Finally, the powder manipulation (weighting operations, solvent removal, spray drying, shaping, etc), easily introduces impurities. All these features must be fully controlled in order to avoid the formation of defects that work as scattering sources thus decreasing the transparency of the material. The important role played by the processing on the transparency of ceramic materials is often underestimated. In the literature a high level of transparency has been reported by many authors but the description of the experimental process, in particular of the powder treatment and shaping, is seldom extensively described and important information that are necessary to reproduce the described results are often missing. The main goal of the present study therefore is to give additional information on the way the experimental features affect the microstructural evolution of YAG-based ceramics and thus the final properties, in particular transparency. Commercial powders are used to prepare YAG materials doped with Nd or Yb by reactive sintering under high vacuum. These dopants have been selected as the more appropriate for high energy and high peak power lasers. As far as it concerns the powder treatment, the thesis focuses on the influence of the solvent removal technique (rotavapor versus spray drying of suspensions in ethanol), the ball milling duration and speed, suspension concentration, solvent ratio, type and amount of dispersant. The influence of the powder type and process on the powder packing as well as the pressure conditions during shaping by pressing are also described. Finally calcination, sintering under high vacuum and in clean atmosphere, and post sintering cycles are studied and related to the final microstructure analyzed by SEM-EDS and HR-TEM, and to the optical and laser properties.

Struktur-Dynamik-Beziehungen in amorphen festen Lösungen

Feste Lösungen homogen dispergierter Wirkstoffmoleküle in amorphen Polymermatrizen sind wichtige Materialien in vielen pharmazeutischen Anwendungen, bei denen eine kontrollierte Abgabe wasserunlöslicher Wirkstoffe in wässrige Systeme eine Rolle spielt. Die intermolekulare Bindungs-stärke zwischen Polymer- und Wirkstoffmolekülgruppen bestimmt die Stabilität der festen Lösung und steuert somit die biologische Aktivität der Wirkstoffmoleküle. In festen Lösungen, die aus acryl-säurehaltigen Copolymeren (Protonendonoren) und basischen Wirkstoffmolekülen (Protonenakzepto-ren) hergestellt werden, sind intermolekulare Wasserstoffbrücken zwischen den Systemkomponenten Triebkraft für die Bildung einer stabilen homogenen Dispersion und für die Entstehung struktureller Merkmale zwischen den Molekülgruppen der Systemkomponenten. Zudem ist die Bindungsstärke der Wasserstoffbrücken im Hinblick auf die kontrollierte Abgabe der Wirkstoffe von Bedeutung. Da dynamische chemische Gleichgewichte bei der Bildung der Wasserstoffbrücken eine wichtige Rolle spielen müssen neben strukturellen Parametern auch dynamische Faktoren beleuchtet werden. Ziel dieser Arbeit ist neben der Ermittlung von intermolekularen Bindungsstärken vor allem die Identifika-tion struktureller Verhältnisse zwischen den Systemkomponenten auf molekularer Ebene. Die Be-stimmung der Abhängigkeit dieser Parameter von der Struktur der verwendeten Polymere und einer Vielzahl weiterer Einflüsse wie z.B. Feuchtigkeit, Lagerdauer oder Wirkstoffkonzentration soll ein kontrolliertes Design fester Lösungen mit definierten anwendungsspezifischen Eigenschaften ermögli-chen. Temperaturabhängige 1H-Festkörper-MAS-NMR (Magic Angle Spinning Nuclear Magnetic Resonance) Experimente an festen Lösungen mit unterschiedlichen Copolymer-Zusammensetzungen weisen die Existenz dynamischer chemischer Gleichgewichte in den komplexen Wasserstoffbrücken-netzwerken nach. Veränderungen in der chemischen Verschiebung und in der Linienform der Reso-nanzlinien acider Protonen erlauben einen tiefen Einblick in die Architektur dieser Netzwerke und legen die Bindungsverhältnisse unter Berücksichtigung der Polymerchemie und der Mobilität der Systemkomponenten dar, wobei die Befunde mithilfe quantenchemischer Rechnungen untermauert werden können. Die Gegenwart acider Protonen ermöglicht einen einfachen 1H-2H-Austausch, wor-aufhin mithilfe rotorsynchronisierter temperaturabhängiger 2H-MAS-NMR Experimente die Wasser-stoffbrückenbindungsstärke bestimmt werden kann. Mit 1H-1H-Korrelationsexperimenten (Doppelquantenspektroskopie) stehen Methoden für die Bestimmung homonuklearer dipolarer 1H-1H-Kopplungen zur Verfügung, die strukturelle Aussagen aufgrund von bevorzugten räumlichen Kontak-ten bestimmter Molekülgruppen ermöglichen. Weiterhin können diese Experimente verwendet werden, um Wasserstoffbrücken zwischen Polymergruppen von Polymer-Wirkstoff-Wasserstoffbrücken zu unterscheiden, wodurch eine quantitative Beschreibung des Bindungsnetzwerks und der Konkurrenz-prozesse zwischen den einzelnen wasserstoffverbrückten Spezies ermöglicht wird. Eine Kristallisation der Wirkstoffmoleküle ist in vielen Anwendungen unerwünscht, da sie die biologische Verfügbarkeit des Wirkstoffs reduzieren. Mit 1H-Festkörper-MAS-NMR Experimenten können kristalline von amorph dispergierten Wirkstoffmolekülen unterschieden werden, wodurch eine Quantifizierung der Destabilisierungsprozesse ermöglicht wird, die durch Exposition der festen Lösungen mit Wasserdampf ausgelöst werden können. Die Zeit- und Konzentrationsabhängigkeit der Wasseraufnahme kann mit NMR-Experimenten verfolgt werden, wobei unterschiedlich mobile Was-serspezies an unterschiedlichen Bindungsorten identifiziert werden können, was zum molekularen Verständnis der Destabilisierungsprozesse beiträgt. Zusätzlich wird die Mobilität der Wirkstoffmole-küle bestimmt, die sich – wie auch die Wirkstoffkonzentration - als wichtige Größe in der Beschrei-bung der Destabilisierung erweist. Aufbauend auf den Beobachtungen wird ein Zusammenhang zwischen der Copolymerzusammensetzung und einer kritischen Wirkstoffkonzentration hergestellt, der für die Anwendungen amorpher fester Lösungen in biologischen Systemen von großer Bedeutung ist.