@article{PaxtonSmolanBoecketal.2017, author = {Paxton, Naomi and Smolan, Willi and B{\"o}ck, Thomas and Melchels, Ferry and Groll, J{\"u}rgen and Jungst, Tomasz}, title = {Proposal to assess printability of bioinks for extrusion-based bioprinting and evaluation of rheological properties governing bioprintability}, series = {Biofabrication}, volume = {9}, journal = {Biofabrication}, number = {4}, doi = {10.1088/1758-5090/aa8dd8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254061}, year = {2017}, abstract = {The development and formulation of printable inks for extrusion-based 3D bioprinting has been a major challenge in the field of biofabrication. Inks, often polymer solutions with the addition of crosslinking to form hydrogels, must not only display adequate mechanical properties for the chosen application but also show high biocompatibility as well as printability. Here we describe a reproducible two-step method for the assessment of the printability of inks for bioprinting, focussing firstly on screening ink formulations to assess fibre formation and the ability to form 3D constructs before presenting a method for the rheological evaluation of inks to characterise the yield point, shear thinning and recovery behaviour. In conjunction, a mathematical model was formulated to provide a theoretical understanding of the pressure-driven, shear thinning extrusion of inks through needles in a bioprinter. The assessment methods were trialled with a commercially available cr{\`e}me, poloxamer 407, alginate-based inks and an alginate-gelatine composite material. Yield stress was investigated by applying a stress ramp to a number of inks, which demonstrated the necessity of high yield for printable materials. The shear thinning behaviour of the inks was then characterised by quantifying the degree of shear thinning and using the mathematical model to predict the window of printer operating parameters in which the materials could be printed. Furthermore, the model predicted high shear conditions and high residence times for cells at the walls of the needle and effects on cytocompatibility at different printing conditions. Finally, the ability of the materials to recover to their original viscosity after extrusion was examined using rotational recovery rheological measurements. Taken together, these assessment techniques revealed significant insights into the requirements for printable inks and shear conditions present during the extrusion process and allow the rapid and reproducible characterisation of a wide variety of inks for bioprinting.}, language = {en} } @phdthesis{Wilhelm2005, author = {Wilhelm, Thomas}, title = {Konzeption und Evaluation eines Kinematik/Dynamik-Lehrgangs zur Ver{\"a}nderung von Sch{\"u}lervorstellungen mit Hilfe dynamisch ikonischer Repr{\"a}sentationen und graphischer Modellbildung}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39554}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2005}, abstract = {Auch nach dem herk{\"o}mmlichen Mechanikunterricht in der Oberstufe verf{\"u}gen viele Sch{\"u}ler nicht {\"u}ber angemessene physikalische Vorstellungen {\"u}ber die verwendeten physikalischen Begriffe und deren Zusammenh{\"a}nge. Einf{\"u}hrend wurden in dieser Arbeit allgemeine Aspekte zu Sch{\"u}lervorstellungen (Kapitel 2.1) sowie konkrete Sch{\"u}lervorstellungen zur Mechanik (Kapitel 2.2) und relevante Lehrervorstellungen (Kapitel 2.3) dargelegt. Ein Ziel dieser Arbeit war, ein Gesamtkonzept f{\"u}r einen ver{\"a}nderten Kinematik- und Dynamikunterricht ein- und zweidimensionaler Bewegungen in der Jahrgangsstufe 11 des Gymnasiums zu entwickeln, das m{\"o}glichst vielen Sch{\"u}lern hilft, m{\"o}glichst viele Fehlvorstellungen zur Mechanik aufzuarbeiten. Dazu wurden u.a. computergest{\"u}tzte Experimente und die Visualisierung der physikalischen Gr{\"o}ßen mit dynamisch ikonischen Repr{\"a}sentationen (siehe Kapitel 3.2) eingesetzt, was neue Elementarisierungen und neue Unterrichtsstrategien erm{\"o}glichte (siehe Kapitel 8.2 oder Kapitel 5). Um gute Chancen zu haben, dass dieses Konzept den Schulalltag erreicht, wurde es lehrplankonform zum bayerischen Lehrplan konzipiert. Eine erste Zielsetzung der summativen Evaluation war festzustellen, inwieweit das gesamte Unterrichtskonzept von verschiedenen Lehrern durchf{\"u}hrbar ist und wie diese es einsch{\"a}tzen (siehe Kapitel 8.4 oder Kapitel 6.3). Ein wichtiges Ziel war dann, mit Hilfe von Tests festzustellen, inwieweit es Ver{\"a}nderungen in den Sch{\"u}lervorstellungen gab (Vor-/Nachtest-Design) und diese Ver{\"a}nderungen mit konventionell unterrichteten Klassen zu vergleichen (Trainings-/Kontrollgruppen-Design) (konventionelle Klassen: Kapitel 8.1; Vergleich: Kapitel 8.5; Kapitel 6.4 + 6.5). Dazu wurden haupts{\"a}chlich bereits vorliegende paper-pencil-Tests verwendet, da eine Testneuentwicklung im Rahmen der Arbeit nicht m{\"o}glich gewesen w{\"a}re. Da diese Tests verschiedene Schw{\"a}chen haben, wurden mehrere verschiedene Tests gleichzeitig eingesetzt, die sich gegenseitig erg{\"a}nzen. Die graphische Modellbildung in Verbindung mit Animationen ist ein fakultativer Teil dieses Unterrichtskonzeptes. Hierzu wurde zus{\"a}tzlich eine eigene Interventionsstudie durchgef{\"u}hrt (siehe Kapitel 8.3 und Kapitel 4). Ergebnisse: Dynamisch ikonische Repr{\"a}sentationen k{\"o}nnen dem Lehrer neue unterrichtliche M{\"o}glichkeiten geben und somit dem Sch{\"u}ler helfen, physikalische Konzepte angemessener zu verstehen. Die Einf{\"u}hrung kinematischer Gr{\"o}ßen anhand zweidimensionaler Bewegungen, die nur mit ikonischen Repr{\"a}sentationen in Form von Vektorpfeilen sinnvoll ist (geeignete Elementarisierung), f{\"u}hrt zu einem physikalischeren Verst{\"a}ndnis des Beschleunigungsbegriffes und vermeidet Fehlvorstellungen durch eine ungeeignete Reduktion auf den Spezialfall eindimensionaler Bewegungen. Mehr Sch{\"u}ler konzeptualisieren Beschleunigung wie in der Physik als gerichtete Gr{\"o}ße anstelle einer Gr{\"o}ße, die die {\"A}nderung des Geschwindigkeitsbetrages angibt und allenfalls tangentiale Richtung haben kann. Auch in der Dynamik sind dadurch hilfreiche Darstellungen und so sinnvolle Ver{\"a}nderungen des Unterrichts m{\"o}glich. Um wesentliche Strukturen aufzuzeigen, werden komplexere Versuche mit mehreren Kr{\"a}ften und Reibung eingesetzt, was erst durch eine rechnerunterst{\"u}tzte Aufbereitung mit dynamisch ikonischen Repr{\"a}sentationen erm{\"o}glicht wird. Diese Darstellungen erm{\"o}glichen auch eine aktive Auseinandersetzung der Sch{\"u}ler mit den Themen, indem von ihnen h{\"a}ufig Vorhersagen gefordert werden (geeignete Unterrichtsstrategie). Graphische Modellbildung als weiterer Einsatz bildlicher Darstellungen kann ebenso eine weitere Verst{\"a}ndnishilfe sein. Sch{\"u}ler, die nach dem vorgelegten Unterrichtskonzept unterrichtet wurden, zeigten mehr Verst{\"a}ndnis f{\"u}r den newtonschen Kraftbegriff. Da die entwickelten Ideen tats{\"a}chlich im Unterricht ankamen und dort Ver{\"a}nderungen bewirkten, kann von einer effektiven Lehrerfortbildung mit Transferwirkung gesprochen werden.}, subject = {Physikunterricht}, language = {de} } @phdthesis{Gerner2023, author = {Gerner, Bettina}, title = {Improvement of oral antineoplastic therapy by means of pharmacometric approaches \& therapeutic drug monitoring}, doi = {10.25972/OPUS-32196}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-321966}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {Oral antineoplastic drugs are an important component in the treatment of solid tumour diseases, haematological and immunological malignancies. Oral drug administration is associated with positive features (e.g., non-invasive drug administration, outpatient care with a high level of independence for the patient and reduced costs for the health care system). The systemic exposure after oral intake however is prone to high IIV as it strongly depends on gastrointestinal absorption processes, which are per se characterized by high inter-and intraindividual variability. Disease and patient-specific characteristics (e.g., disease state, concomitant diseases, concomitant medication, patient demographics) may additionally contribute to variability in plasma concentrations between individual patients. In addition, many oral antineoplastic drugs show complex PK, which has not yet been fully investigated and elucidated for all substances. All this may increase the risk of suboptimal plasma exposure (either subtherapeutic or toxic), which may ultimately jeopardise the success of therapy, either through a loss of efficacy or through increased, intolerable adverse drug reactions. TDM can be used to detect suboptimal plasma levels and prevent permanent under- or overexposure. It is essential in the treatment of ACC with mitotane, a substance with unfavourable PK and high IIV. In the current work a HPLC-UV method for the TDM of mitotane using VAMS was developed. A low sample volume (20 µl) of capillary blood was used in the developed method, which facilitates dense sampling e.g., at treatment initiation. However, no reference ranges for measurements from capillary blood are established so far and a simple conversion from capillary concentrations to plasma concentrations was not possible. To date the therapeutic range is established only for plasma concentrations and observed capillary concentrations could not be reliable interpretated.The multi-kinase inhibitor cabozantinib is also used for the treatment of ACC. However, not all PK properties, like the characteristic second peak in the cabozantinib concentration-time profile have been fully understood so far. To gain a mechanistic understanding of the compound, a PBPK model was developed and various theories for modelling the second peak were explored, revealing that EHC of the compound is most plausible. Cabozantinib is mainly metabolized via CYP3A4 and susceptible to DDI with e.g., CYP3A4 inducers. The DDI between cabozantinib and rifampin was investigated with the developed PBPK model and revealed a reduced cabozantinib exposure (AUC) by 77\%. Hence, the combination of cabozantinib with strong CYP inducers should be avoided. If this is not possible, co administration should be monitored using TDM. The model was also used to simulate cabozantinib plasma concentrations at different stages of liver injury. This showed a 64\% and 50\% increase in total exposure for mild and moderate liver injury, respectively.Ruxolitinib is used, among others, for patients with acute and chronic GvHD. These patients often also receive posaconazole for invasive fungal prophylaxis leading to CYP3A4 mediated DDI between both substances. Different dosing recommendations from the FDA and EMA on the use of ruxolitinib in combination with posaconazole complicate clinical use. To simulate the effect of this relevant DDI, two separate PBPK models for ruxolitinib and posaconazole were developed and combined. Predicted ruxolitinib exposure was compared to observed plasma concentrations obtained in GvHD patients. The model simulations showed that the observed ruxolitinib concentrations in these patients were generally higher than the simulated concentrations in healthy individuals, with standard dosing present in both scenarios. According to the developed model, EMA recommended RUX dose reduction seems to be plausible as due to the complexity of the disease and intake of extensive co-medication, RUX plasma concentration can be higher than expected.}, subject = {Arzneimittel{\"u}berwachung}, language = {en} } @phdthesis{Kuells2000, author = {K{\"u}lls, Christoph}, title = {Groundwater of the North-Western Kalahari, Namibia}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-1180680}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2000}, abstract = {A quantitative model of groundwater flows contributing to the Goblenz state water scheme at the north-western fringe of the Kalahari was developed within this study. The investigated area corresponds to the Upper Omatako basin and encompasses an outer mountainous rim and sediments of the Kalahari sand desert in the centre. This study revealed the eminent importance of the mountainous rim for the water balance of the Kalahari, both in terms of surface and ground water. A hydrochemical subdivision of groundwater types in the mountain rim around the Kalahari was derived from cluster analysis of hydrochemical groundwater data. The western and south-western secondary aquifers within rocks of the Damara Sequence, the Otavi Mountain karst aquifers of the Tsumeb and Abenab subgroups as well as the Waterberg Etjo sandstone aquifer represent the major hydrochemical groups. Ca/Mg and Sr/Ca ratios allowed to trace the groundwater flow from the Otavi Mountains towards the Kalahari near Goblenz. The Otavi Mountains and the Waterberg were identified as the main recharge areas showing almost no or only little isotopic enrichment by evaporation. Soil water balance modelling confirmed that direct groundwater recharge in hard-rock environments tends to be much higher than in areas covered with thick Kalahari sediments. According to the water balance model average recharge rates in hard-rock exposures with only thin sand cover are between 0.1 and 2.5 \% of mean annual rainfall. Within the Kalahari itself very limited recharge was predicted (< 1 \% of mean annual rainfall). In the Upper Omatako basin the highest recharge probability was found in February in the late rainfall season. The water balance model also indicated that surface runoff is produced sporadically, triggering indirect recharge events. Several sinkholes were discovered in the Otavi Foreland to the north of Goblenz forming short-cuts to the groundwater table and preferential recharge zones. Their relevance for the generation of indirect recharge could be demonstrated by stable isotope variations resulting from observed flood events. Within the Kalahari basin several troughs were identified in the pre-Kalahari surface by GIS-based analyses. A map of saturated thickness of Kalahari sediments revealed that these major troughs are partly saturated with groundwater. The main trough, extending from south-west to north-east, is probably connected to the Goblenz state water scheme and represents a major zone of groundwater confluence, receiving groundwater inflows from several recharge areas in the Upper Omatako basin. As a result of the dominance of mountain front recharge the groundwater of the Kalahari carries an isotopic composition of recharge at higher altitudes. The respective percentages of inflow into the Kalahari from different source areas were determined by a mixing-cell approach. According to the mixing model Goblenz receives most of its inflow (70 to 80 \%) from a shallow Kalahari aquifer in the Otavi Foreland which is connected to the Otavi Mountains. Another 15 to 10 \% of groundwater inflow to the Kalahari at Goblenz derive from the Etjo sandstone aquifer to the south and from inflow of a mixed component. In conclusion, groundwater abstraction at Goblenz will be affected by measures that heavily influence groundwater inflow from the Otavi Mountains, the Waterberg, and the fractured aquifer north of the Waterberg.}, subject = {Kalahari}, language = {en} } @phdthesis{Delporte2009, author = {Delporte, Marc}, title = {A phenomenological approach to the prediction of material behaviours during co-sintering}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-44235}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2009}, abstract = {This work deals with the sintering of multi-material composites. It aims at the establishment of an alternative to the existing complex models for sintering. The development of the associated experimental procedure is also included in this work. The developed material model must be able to predict (i) the sintering kinetics and (ii) the viscous moduli of a material. An experimental approach with free sintering and hot-forging measurements is favoured in this work. The prediction of the sintering kinetics is addressed with the construction of a map of sintering kinetics data: the Master Sintering Diagram (MSD). The MSD is based on a generalized equation for solid-state diffusion, thus is suitable for any thermal activated diffusion. The MSD allows the prediction of sintering kinetics for a large range of temperatures and external loads. A novel approach to the determination of the viscous moduli is developed in this work: the cyclic unloading method. It is a hot-forging measurement (sintering under uniaxial compression) where the applied load is released for short periods. The measurements are carried out with continuous heating, so that the viscous moduli are determined over large ranges of temperatures and densities. The advantage of this method is the measurement of the viscous moduli in anisotropic microstructures. The material model is validated in two steps. Firstly, the predictions of sintering kinetics with the MSD are compared with experimental results: changes of thermal profile and changes of load are predicted with a maximum deviation of 10\%. Secondly, the experimentally determined viscous moduli are used for the prediction of a bi-layer curvature using models for warpage from literature. The prediction is qualitatively good for a maximum deviation of 27\%. The study of a sintering glass-ceramic tape on a rigid substrate is presented. It shows that this co-sintering problem can be qualitatively investigated with requirement of the material model. The formation of anisotropy intrinsic to the hot-forging experiments is also reported in this work. It appears to be a important point to address in the future for a better understanding of the cosintering.}, subject = {Sintern}, language = {en} }