Interpolyelektrolytkomplexe zylindrischer Bürstenpolymere

Die elektrostatische Wechselwirkung zwischen entgegengesetzt geladenen Polyelektrolyten führt zur spontanen Bildung von Interpolyelektrolytkomplexen. Besonders im Fokus des akademischen und biotechnologischen Interesses stehen derzeit Komplexe aus DNA und synthetischen Polykationen, da eine Anwendung dieser speziellen Interpolyelektrolytkomplexe in der nicht-viralen Gentherapie vielfältig diskutiert wird. Ziel der vorliegenden Arbeit war es, den Einfluss von Kettensteifheit auf die Bildung von Interpolyelektrolytkomplexen zu untersuchen und dabei Wege aufzuzeigen, die eine Kontrolle der Topologie von Interpolyelektrolytkomplexen ermöglichen. Neben dem topologischen Einfluss wurde untersucht, wie durch Komplexierung hochmolekularer Polyelektrolyte equilibrierbare Strukturen erhalten werden können. Als Modellsystem für diese Untersuchungen wurden zylindrische Bürstenpolymere verwendet, denen als topologischer „Kontrast“ das Komplexierungsverhalten kommerzieller PAMAM-G5-Dendrimere mit kugelförmiger Topologie gegenüber gestellt wurde. Um den Ladungsgrad des Bürstenpolymers beliebig variieren zu können, wurden Bürstenpolymere mit Poly(ethylenimin)-Seitenketten synthetisiert, deren Ladungsdichte über den Protonierungsgrad einstellbar ist. Die vorliegende Arbeit zeigt, wie diese mit Hilfe der Makromonomermethode hergestellt werden konnten. Die Komplexbildung von DNA mit semiflexiblen zylindrischen Bürstenpolymeren mit unterschiedlichen Seitenketten und Ladungsdichten in wässriger Lösung hat gezeigt, dass diese in allen untersuchten Fällen unter kinetischer Kontrolle verläuft und Nicht-Gleichgewichtsstrukturen gebildet werden. Sehr überraschend wurde festgestellt, dass die Größen der mit vorgelegter DNA gebildeten Komplexe ungeachtet des verwendeten Polykations identisch sind und DNA-Komplexe mit einem Radius von 30 bis 50 nm und einer kugelförmigen Topologie resultieren. Diese kinetisch kontrollierte Komplexbildung konnte in nicht-wässriger Lösung durch starke Reduktion der Anzahl wechselwirkender Ladungen verhindert werden, so dass eine thermodynamische Kontrolle möglich wurde. Unter diesen Bedingungen ist es gelungen, aus hochgeladenen Poly(styrolsulfonat)-Bürsten mit modifizierten Poly(ethylenimin)-Bürsten oder PAMAM-Dendrimeren Komplexe zylindrischer Topologie herzu-stellen. Für letztere konnte darüber hinaus postuliert werden, dass diese Komplexe eine dichteste Packung der PAMAM-Dendrimere darstellen, für deren Bildung das Polyanion mit seiner größeren Konturlänge und seiner zylindrischen Topologie als Templat dient.

Investigation of the dipole response of nickel isotopes in the presence of a high-frequency electromagnetic field

The electric dipole response of neutron-rich nickel isotopes has been investigated using the LAND setup at GSI in Darmstadt (Germany). Relativistic secondary beams of 56−57Ni and 67−72Ni at approximately 500 AMeV have been generated using projectile fragmentation of stable ions on a 4 g/cm2 Be target and subsequent separation in the magnetic dipole fields of the FRagment Separator (FRS). After reaching the LAND setup in Cave C, the radioactive ions were excited electromagnetically in the electric field of a Pb target. The decay products have been measured in inverse kinematics using various detectors. Neutron-rich 67−69Ni isotopes decay by the emission of neutrons, which are detected in the LAND detector. The present analysis concentrates on the (gamma,n) and (gamma,2n) channels in these nuclei, since the proton and three-neutron thresholds are unlikely to be reached considering the virtual photon spectrum for nickel ions at 500 AMeV. A measurement of the stable 58Ni isotope is used as a benchmark to check the accuracy of the present results with previously published data. The measured (gamma,n) and (gamma,np) channels are compared with an inclusive photoneutron measurement by Fultz and coworkers, which are consistent within the respective errors. The measured excitation energy distributions of 67−69Ni contain a large portion of the Giant Dipole Resonance (GDR) strength predicted by the Thomas-Reiche-Kuhn energy-weighted sum rule, as well as a significant amount of low-lying E1 strength, that cannot be attributed to the GDR alone. The GDR distribution parameters are calculated using well-established semi-empirical systematic models, providing the peak energies and widths. The GDR strength is extracted from the chi-square minimization of the model GDR to the measured data of the (gamma,2n) channel, thereby excluding any influence of eventual low-lying strength. The subtraction of the obtained GDR distribution from the total measured E1 strength provides the low-lying E1 strength distribution, which is attributed to the Pygmy Dipole Resonance (PDR). The extraction of the peak energy, width and strength is performed using a Gaussian function. The minimization of trial Gaussian distributions to the data does not converge towards a sharp minimum. Therefore, the results are presented by a chi-square distribution as a function of all three Gaussian parameters. Various predictions of PDR distributions exist, as well as a recent measurement of the 68Ni pygmy dipole-resonance obtained by virtual photon scattering, to which the present pygmy dipole-resonance distribution is also compared.

Valutazioni ambientali mediante life cycle assessment (LCA) sui mattoni in terra cruda: il caso studio di pabillonis

Il documento parte da una analisi generale sulle tecnologie site-specific, concentrandosi poi maggiormente sulle costruzioni in terra cruda. Viene descritta l'analisi del ciclo di vita fatta sui mattoni in terra cruda e sulla parete realizzata con questi mattoni, messa poi a confronto con una parete realizzata in laterizi. Infine è presenta l'analisi dei costi esterni sul ciclo di vita dei mattoni in terra cruda.

La gestione delle relazioni tra soggetto produttore e risorse archivistiche nel semantic web. Un modello ontologico

La ricerca nel campo del cultural heritage management ha adottato negli ultimi decenni le tecnologie web quali strumenti privilegiati per stabilire i nuovi approcci e indirizzi nella valorizzazione della conoscenza. Questa tesi si colloca nell'ambito interdisciplinare tra le scienze umanistiche e informatiche e si fonda sulla consapevolezza del reciproco arricchimento che può derivare dal continuo confronto, le une disponendo di mezzi più espressivi e popolari per divulgare il proprio patrimonio e le altre usufruendo di “materia prima” autorevole (ossia dati strutturati di qualità e alto livello di fiducia) in fase di sperimentazione. Lo studio dei punti di tangenza tra le discipline muove da due ambiti precisi, ovvero le applicazioni informatiche nel campo dell'archivistica e gli sviluppi del semantic web nel settore delle digital humanities.

Function Point e Real Time Software: caso di studio reale

La tesi si pone come obiettivo quello di analizzare dal punto di vista funzionale il software embedded real - time installato su di una applicazione industriale, utilizzando la prima release per calibrare il sistema in modo da poter stimare il numero di linee di codice necessarie per lo sviluppo delle versioni successive. Durante questo studio sono stati applicati i metodi indicati dall'ingegneria del software per contare le linee di codice sorgente dell'applicativo e stimarne i function point, analizzando ed individuando le problematiche relative all'utilizzo di tali strumenti su software di tipo real - time.

[Only a denture sore? Causes of a possible denture sore from a maxillary complete denture]

This case presentation documents the treatment sequence of a 74 years old patient who complained about a sore spot of the palatal mucosa underneath the complete denture. The intraoral examination revealed a dark spot, redness and swelling of the mucosa around this spot and halitosis. The mucosa exhibited a perforation of 3 x 10 mm in diameter. A radiographic 3-D picture showed an impacted canine tooth, which was partly covered by the palatal bone. Firstly the denture base was relieved and the swelling gradually disappeared. Then a biopsy was taken for histological analysis to exclude any malignant process. In local anesthesia the tooth was extracted, which exhibited a deep carious lesion of the entire crown. After surgery a visible collapse of the jaw crest was observed. During a period of two months the denture was relined with a soft material to improve its fit and to enhance the healing process. With a final rebasement, the existing denture could be adapted again and the patient continued to wear it.

Sequence capture and next-generation resequencing of multiple tagged nucleic acid samples for mutation screening of urea cycle disorders

Molecular genetic testing is commonly used to confirm clinical diagnoses of inherited urea cycle disorders (UCDs); however, conventional mutation screenings encompassing only the coding regions of genes may not detect disease-causing mutations occurring in regulatory elements and introns. Microarray-based target enrichment and next-generation sequencing now allow more-comprehensive genetic screening. We applied this approach to UCDs and combined it with the use of DNA bar codes for more cost-effective, parallel analyses of multiple samples.