Background: Collagen cross-linking of the sclera is a promising approach to strengthen scleral rigidity and thus to inhibit eye growth in progressive myopia. Additionally, cross-linking might inhibit degrading processes in idiopathic melting or in ocular inflammatory diseases of the sclera. Different cross-linking treatments were tested to increase resistance to enzymatic degradation of the rabbit sclera. Methods: Scleral patches from rabbit eyes were cross-linked using paraformaldehyde, glutaraldehyde or riboflavin combined with UV-A-light or with blue light. The patches were incubated with collagenase I (MMP1) for various durations up to 24 h to elucidate differences in scleral resistance to enzymatic degradation. Degraded protein components in the supernatant were detected and quantified using measurements of Fluoraldehyde o-Phthaldialdehyde (OPA) fluorescence . Results: All cross-linking methods reduced the enzymatic degradation of rabbit scleral tissue by MMP1. Incubation with glutaraldehyde (1%) and paraformaldehyde (4%) caused nearly a complete inhibition of enzymatic degradation (down to 7% ± 2.8 of digested protein compared to control). Cross-linking with riboflavin/UV-A-light reduced the degradation by MMP1 to 62% ± 12.7 after 24 h. Cross-linking with riboflavin/blue light reduced the degradation by MMP1 to 77% ± 13.5 after 24 h. No significant differences could be detected comparing different light intensities, light exposure times or riboflavin concentrations. Conclusions: The application of all cross-linking methods increased the resistance of rabbit scleral tissue to MMP1-degradation. Especially, gentle cross-linking with riboflavin and UV-A or blue light might be a clinical approach in future.

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The use of degradable biomedical materials has during the past decades indeed modernized medical science, finding applications in e.g. tissue engineering and drug delivery. The key question is to adapt the material with respect to mechanical properties, surface characteristics and degradation profile to suit the specific application. Degradation products are generally considered non-toxic and they are excreted from the human body. However, large amounts of hydroxy acids may induce a pH decrease and a subsequent inflammatory response at the implantation site. In this study, macromolecular design and a combination of cross-linking and adjusted hydrophilicity are utilized as tools to control and tailor degradation rate and subsequent release of degradation products from biomedical polyester-ethers. A series of different homo- and copolymers of -caprolactone (CL) and 1,5-dioxepan-2-one (DXO) were synthesized and their hydrolytic degradation was monitored in phosphate buffer solution at pH 7.4 and 37 °C for up to 546 days. The various materials comprised linear DXO/CL triblock and multiblock copolymers, PCL linear homopolymer and porous structure, and random cross-linked homo- and copolymers of CL/DXO using 2,2’-bis-(ε-caprolactone-4-yl) propane (BCP) as a cross-linking agent. The results showed that macromolecular engineering and controlled hydrophilicity of cross-linked networks were useful implements for customizing the release rate of acidic degradation products in order to prevent the formation of local acidic environments and thereby reduce the risk of inflammatory responses in the body. / QC 20101109

Urban structure is designed as a new centre of this city quarter with services, leisure time activities and new appartments. Leisure time centre is intended for adult as a educational and sport centre. It consist of two buildings conected by urban pedestrián bridge. The object is dominant of this area and links two quarters. The facade is design from concrete and red horizontal lamella blinds.

Guidelines to screen and select common items for vertical scaling have been adopted from equating. Differences between vertical scaling and equating suggest that these guidelines may not apply to vertical scaling in the same way that they apply to equating. For example, in equating the examinee groups are assumed to be randomly equivalent, but in vertical scaling the examinee groups are assumed to possess different levels of proficiency. Equating studies that examined the characteristics of the common-item set stress the importance of careful item selection, particularly when groups differ in ability level. Since in vertical scaling cross-level ability differences are expected, the common items' psychometric characteristics become even more important in order to obtain a correct interpretation of students' academic growth. This dissertation applied two screening criteria and two selection approaches to investigate how changes in the composition of the linking sets impacted the nature of students' growth when creating vertical scales for two elementary mathematics tests. The purpose was to observe how well these equating guidelines were applied in the context of vertical scaling. Two separate datasets were analyzed to observe the impact of manipulating the common items' content area and targeted curricular grade level. The same Rasch scaling method was applied for all variations of the linking set. Both the robust z procedure and a variant of the 0.3-logit difference procedure were used to screen unstable common items from the linking sets. (In vertical scaling, a directional item-difficulty difference must be computed for the 0.3-logit difference procedure.) Different combinations of stable common items were selected to make up the linking sets. The mean/mean method was used to compute the equating constant and linearly transform the students' test scores onto the base scale. A total of 36 vertical scales were created. The results indicated that, although the robust z procedure was a more conservative approach to flagging unstable items, the robust z and the 0.3-logit difference procedure produced similar interpretations of students' growth. The results also suggested that the choice of grade-level-targeted common items affected the estimates of students' grade-to-grade growth, whereas the results regarding the choice of content-area-specific common items were inconsistent. The findings from the Geometry and Measurement dataset indicated that the choice of content-area-specific common items had an impact on the interpretation of students' growth, while the findings from the Algebra and Data Analysis/Probability dataset indicated that the choice of content-area-specific common items did not appear to significantly affect students' growth. A discussion of the limitations of the study and possible future research is presented.

Surface meshing algorithms require certain relationships among the number of intervals on the curves that bound the surface. Assigning the number of intervals to all of the curves in the model such that all relationships are satisfied is called interval assignment. Volume meshing algorithms also require certain relationships among the numbers of intervals on each of the curves on the volume. These relationships are not always captured by surface meshing requirements. This thesis presents a news technique for automatically identifying volume constraints. In this technique, volume constraints are grouped with surface constraints and are solved simultaneously. A sweepable volume has source, target and linking surfaces. The technique described in this thesis uses graph algorithms to identify independent, parallel sets of linking surfaces, and determine if they correspond to through-holes or blind-holes. For blind-holes, the algorithm generates constraints that prevent the hole from being too deep in interval parameter space and, thus, penetrating opposite target surfaces. For each linking set, the adjoining source and target surfaces are partially ordered by the structure of the linking set. A small set of representative paths for each linking set is found, and the representative paths for all linking sets are gathered and distilled by Gaussian elimination into a small set of constraints.

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The use of cell transplantation to treat enzyme deficiency disorders is limited by the immune response targeted against foreign tissue or the use of life-long immunosuppressants. Hiding cells from the immune system in an encapsulation device is promising. Cells encapsulated within an anionic calcium alginate hydrogel bead are protected through a semi-permeable membrane formed by polycation, poly-L-lysine (PLL). A final layer of alginate is added to hide the cationic PLL surface but this has proved to be difficult creating capsules which are prone to fibrotic overgrowth, blocking exchange of nutrients, waste and therapeutic enzymes through the capsule. For long term applications these capsules need to be both biocompatible and mechanically robust. This thesis aims to address the biocompatibility issue of high cationic surface charge by synthesizing polycations of reduced charge using N-(3- aminopropyl)methacrylamide hydrochloride (APM) and N-(2- hydroxypropyl)methacrylamide (HPM) and study the associated mechanical properties of the capsules using micropipette aspiration. Micropipette aspiration was applied and validated for alginate based capsules (gel and liquid core) to quantify stiffness. Varying ratios of APM were used to control the overall charge of the polycations formed while HPM was incorporated as a neutral, hydrophilic, nonfouling comonomer. The molecular weight (MW) was controlled by using reversible addition-fragmentation chain transfer (RAFT) polymerization. The biocompatibility of these polymers was tested by cell adhesion and proliferation of 3T3 fibroblasts onto APM/HPM copolymer functionalized surfaces and by solution toxicity against C2C12 myoblasts. The ability for the APM/HPM copolymers to bind to alginate and form capsules was also assessed, along with the integrity and stiffness of the capsule membrane with or without additional covalent cross-linking by reactive polyanion, poly(methacrylic acid-co-2-vinyl-4,4- dimethylazlactone) (PMV60). Thermo-responsive block copolymers of N-isopropylacrylamide (NIPAM) and 2- hydroxyethylacrylamide (HEA) were also synthesized as potential drug delivery nanoparticles, showing control over micelle morphology with varying NIPAM to HEA ratios. / Thesis / Doctor of Science (PhD) / The treatment of enzyme deficiency disorders by cell transplantation is limited by the immune attack of foreign tissue in absence of immunosuppressants. Cells protected in an encapsulation device has shown promise. Poly-L-lysine, a widely used membrane material in these protective capsules, binds to the anionic gel entrapping living cells because it is highly cationic. The high cationic charge is difficult to hide causing the immune system to build tissue around the capsule, preventing the encapsulated cells from exchanging nutrients and therapeutic enzymes. This thesis aims to replace poly-L-lysine by synthesizing a series of more biocompatible materials of decreasing cationic charge. These materials were studied for the ability to support tissue growth and form stable capsules. The membrane strength was measured using an aspiration method validated for these types of capsules. Reducing the cationic charge of the materials increased the biocompatibility of the capsule membrane but also made for weaker membranes.

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