Das corneale Endothel bildet die innere, einschichtige Zelllage der Cornea und ist für die Aufrechterhaltung der cornealen Transparenz zuständig. Krankheiten oder Verletzungen des cornealen Endothels können zu schweren Beeinträchtigungen des Sehvermögens führen und eine corneale Transplantation erforderlich machen. Der während und nach der Operation auftretende endotheliale Zellverlust erschwert das Überleben des Transplantates. Darum besteht ein Hauptziel des cornealen Tissue Engineerings in der Bereitstellung von transplantierbaren humanen cornealen Endothelzellsheets (HCEC-Sheets) mit einer adäquaten Zelldichte. Thermo-responsive Zellkulturträger fanden für die schonende, enzymfreie Gewinnung von Zellsheets für verschiedene Gewebetypen bereits Verwendung. HCEC stellen in diesem Kontext einen besonderen Fall dar, da sie eine starke Adhäsion zu ihrem Kultursubstrat ausbilden, was deren schonende, thermisch induzierte Ablösung als funktionelles Zellsheet erschwert. Im Rahmen dieser Arbeit wurde ein neuartiger thermo-responsiver Zellkulturträger entwickelt. Dieser basiert auf dem durch Elektronenbestrahlung immobilisierten und vernetzten thermo-responsiven Polymer Poly(vinylmethylether) (PVME) sowie dem alternierenden Co-Polymer Poly(vinylmethylehter-alt-maleinsäureanhydrid) (PVMEMA) als biofunktionalisierbare Komponente. Die Kombination dieser Polymere führte zur Etablierung eines thermo-responsiven Zellkulturträgers, dessen physikochemische und biomolekulare Eigenschaften in weiten Grenzen einstellbar und dadurch an die spezifischen Anforderungen von HCEC anpassbar waren. Das PVME-PVMEMA-Blend ermöglichte die Bildung konfluenter HCEC-Monolayer mit den morphologischen Grundlagen für ein funktionelles corneales Endothelgewebe. Durch Inkorporation von Poly(N-isopropylacrylamid) (PNiPAAm) als weitere thermo-responsive Polymerkomponente konnte das Ablösungsverhalten funktioneller HCEC-Sheets weiter verbessert werden. In einem weiteren Schritt erfolgte der Transfer abgelöster HCEC-Sheets auf ein planares, biofunktionalisiertes Kultursubstrat sowie auf endothelfreie porcine Corneae. Die HCEC-Sheets wurden auch nach dem Transfer umfassend biologisch analysiert. Diese Arbeit legt einen Grundstein für die Bereitstellung klinisch anwendbarer Alternativen für das Tissue Engineering von cornealem Gewebe.

Dynamic signal control provides significant benefits in terms of travel time, travel time reliability, and other performance measures of transportation systems. The goal of this research is to develop and evaluate a methodology to support the planning for operations of dynamic signal control utilizing a multi-resolution analysis approach. The multi-resolution analysis modeling combines analysis, modeling, and simulation (AMS) tools to support the assessment of the impacts of dynamic traffic signal control. Dynamic signal control strategies are effective in relieving congestions during non-typical days, such as those with high demands, incidents with different attributes, and adverse weather conditions. This research recognizes the need to model the impacts of dynamic signal controls for different days representing, different demand and incident levels. Methods are identified to calibrate the utilized tools for the patterns during different days based on demands and incident conditions utilizing combinations of real-world data with different levels of details. A significant challenge addressed in this study is to ensure that the mesoscopic simulation-based dynamic traffic assignment (DTA) models produces turning movement volumes at signalized intersections with sufficient accuracy for the purpose of the analysis. Although, an important aspect when modeling incident responsive signal control is to determine the capacity impacts of incidents considering the interaction between the drop in capacity below demands at the midblock urban street segment location and the upstream and downstream signalized intersection operations. A new model is developed to estimate the drop in capacity at the incident location by considering the downstream signal control queue spillback effects. A second model is developed to estimate the reduction in the upstream intersection capacity due to the drop in capacity at the midblock incident location as estimated by the first model. These developed models are used as part of a mesoscopic simulation-based DTA modeling to set the capacity during incident conditions, when such modeling is used to estimate the diversion during incidents. To supplement the DTA-based analysis, regression models are developed to estimate the diversion rate due to urban street incidents based on real-world data. These regression models are combined with the DTA model to estimate the volume at the incident location and alternative routes. The volumes with different demands and incident levels, resulting from DTA modeling are imported to a microscopic simulation model for more detailed analysis of dynamic signal control. The microscopic model shows that the implementation of special signal plans during incidents and different demand levels can improve mobility measures.

abstract: Environmentally responsive microgels have drawn significant attention due to their intrinsic ability to change volume in response to various external stimuli such as pH, temperature, osmotic pressure, or electric and magnetic fields. The extent of particle swelling is controlled by the nature of the polymer-solvent interaction. This thesis focuses on design and synthesis of environmentally responsive microgels and their composites, and encompasses methods of utilizing microgel systems in applications as vehicles for the adsorption, retention, and targeted delivery of chemical species. Furthermore, self-assembled microgel particles at ionic liquid (IL)-water interfaces demonstrate responsive colloidal lattice morphology. The thesis first reports on the fundamental aspects of synthesis, functionalization, and characteristic properties of multifunctional environmentally responsive microgels derived from poly(N-isopropylacrylamide) (PNIPAm) and other functional co-monomers. In particular, the uptake and release of active chemical species such as rheology modifiers into and from these ionic microgels is demonstrated. Moreover, a facile tunable method for the formation of organic-inorganic composites with Fe3O4 nanoparticles adsorbed and embedded within ionic microgel particles is explored. Additionally, the development of zwitterionic microgels (ZI-MG) is presented. These aqueous ZI-MG dispersions exhibit reversible parabolic swelling as a function of pH and display a minimum hydrodynamic diameter at a tunable isoelectric point (IEP). This study also elucidates the controlled uptake and release of surfactants from these particle systems. The extent of surfactant loading and the ensuing relative swelling/deswelling behaviors within the polymer networks are explained in terms of their binding interactions. The latter part of this thesis highlights the versatility of fluorescently labeled microgel particles as stabilizers for IL-water droplets. When the prepared particles form monolayers and equilibrate at the liquid-liquid interface, the colloidal lattice organization may re-order itself depending on the surface charge of these particles. Finally, it is shown that the spontaneously formed and densely packed layers of microgel particles can be employed for extraction applications, as the interface remains permeable to small active species. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2015

Thesis advisor: Martin Scanlan / This qualitative single-site case study examined how district administrators in one racially, culturally, and linguistically diverse Massachusetts school district supported and strengthened principals’ culturally responsive leadership practice. Building coherent culture and structures that provide space to critically self-reflect and collaboratively learn are essential. Data collection included interviews with district administrators and principals, observations of leadership meetings, document review, and a survey. Findings revealed district administrators established collaborative relationships with principals by employing a coherent service-oriented approach. Participants perceived the intentionality of the superintendent’s efforts as foundational to building trust, however prior experiences with district leadership impeded these efforts. The superintendent controlled sensemaking to signal equity as a district priority, yet the lack of a shared understanding of culturally responsive practice led participants to conflate culturally responsive practice with other district endorsed equity practices. Attempts were made to align structures and tools to equity priorities, however culturally responsive practices were subsumed within other equity initiatives creating variance in the perception of the effectiveness of how structures and tools support principals’ culturally responsive leadership practice. Implications include developing a district definition of culturally responsive practice and using equity practices as a scaffold to support principals’ understanding and enactment of culturally responsive practices that bring critical self-reflection and conversations about racial and cultural bias to the forefront. Future research may extend this study to analyze sensegiving interactions and examine the impact of these interactions on principals’ culturally responsive leadership practice / Thesis (EdD) — Boston College, 2020. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Leadership and Higher Education.

Thesis advisor: Martin Scanlan / Culturally responsive practice (CRP) by educators is an essential tool to serve increasingly diverse public-school populations. This study examines the sensemaking and sensegiving that district central office administrators undertake regarding what it means for educators to be culturally responsive practitioners. This dissertation used a case study of a mid-sized urban district which has not yet undertaken systematic effort on CRP to explore three research questions: (1) How do district administrators understand what it means for educators to be culturally responsive practitioners? (2) How do district administrators seek to influence the cultural responsiveness of educators? (3) What does evidence suggest about the efficacy of these efforts to influence the cultural responsiveness of educators? Data included interviews with seven district administrators and nineteen teachers, a survey of 33 educators in the district, and a review of internal district documents. Findings included that administrators had limited understanding of CRP, though they believe it to be important. They connected CRP to methodologies and practices in which they were more fluent. Sensegiving by district administrators was more effective at conveying the importance of CRP than its meaning or how to implement it. Absent a shared definition of CRP, but with heavy signaling of its importance, educators developed varying conceptions through their sensemaking. This case study suggests several implications for research, policy, and practice, including for the study of sensemaking in multi-layered organizations grappling with multiple changes and for implementation by school districts of CRP, as well as barriers to such implementation. / Thesis (EdD) — Boston College, 2020. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Leadership and Higher Education.

L'intérêt des copolymères amphiphiles se retrouve dans de multiples applications telles que le: supports catalytique, la bio-séparation ou encore la vectorisation de principe actif. L'étude de leu auto-association sous forme micellaire est très étendue notamment via l'utilisation de polymère: intelligents. Cette classe de polymères présente un changement de comportement lors d'un modification de son environnement. Ainsi des polymères pH et thermo-sensibles ont été sélectionnés dans le but d'étudier des systèmes micellaires composés d'un cœur hydrophobe issus de l'huile de lin et d'une couronne hydrophile stimuli-sensible. Cependant, pour chaque application visée, la synthèse de macromolécules de composition et/ou d'architecture complexe possédant de nouvelles propriétés est nécessaire. Afin de contourner les limitations de cette approche, uni alternative reposant sur le mélange physique de copolymères a été étudiée dans le but de moduler les propriétés et combiner deux sensibilités. / Amphiphilic copolymers have attracted a large interest as they find numerous applications in catalyst support, bio-separation devices and drug delivery systems. Their auto-association in aqueous media forming micelles are well-studied, particularly by the use of smart polymers which display a significant physicochemical change in response to modification of their environment. In this work, pH and temperature responsive polymers have been studied for the elaboration of micellar systems composed of a hydrophobic core from linseed oil and hydrophilic stimuli-sensitive coronna. However the common approach is to design one specific macromolecule for one given application, with sometimes complex composition and/or architecture. We aim to investigate a straight-forward pathway towards micellar systems with finely tuned sensitivities by the cooperative self-assembly of two different copolymers to manipulate the physico-chemical behavior of the final mixed system.

Le travail de recherche de cette thèse se concentre sur le développement de nanoparticules de silice organo-hybrides pour des applications en nanomédecine et agroalimentaire. Ces nanoconteneurs de silice, comportant des liens disulfures, sont capables de se briser en petits fragments en présence du milieu réductif intracellulaire. Des nanoparticules présentant de larges pores ont été synthétisées pour la livraison d’un siRNA PLK1 pour le traitement du carcinome hépatocellulaire et ont démontré des résultats prometteurs in vitro et in vivo. Ces particules ont été également utilisées pour charger un peptide cytotoxique, souvent utilisé comme pesticide dans l’industrie agroalimentaire. Les nanoparticules cassables ont ensuite été miniaturisées pour le relargage d’agents thérapeutiques dans des glioblastomes humains. Le système présentait un relargage plus rapide comparé à la forme liposomale actuellement sur le marché. Enfin, des nanoparticules contenant des liens répondant aux réactifs dérivés de l’oxygène ont été développées et ont démontré une fragmentation importante en présence d’oxygène singulet. / The research work presented throughout this thesis focuses on the development of organo-hybrid mesoporous silica nanoparticles for their applications in nanomedicine and crop industry. Disulfide doped silica nanocarriers, able to break down in small pieces in presence of the intracellular reductive environment have been tailored. A large pore stimuli-responsive system was developed to deliver a PLK1 siRNA within hepatocellular carcinoma cells demonstrating promising results both in vitro and in vivo. The particles were further used to deliver a venom peptide, often utilized as esticide in the crop industry. The breakable nanocarriers were further miniaturized for the delivery of chemotherapeutic agents within human glioblastoma cells. The system presented a faster delivery compared to the commercially available liposomal form. Finally, Reactive-Oxygen-Species-responsive mesoporous silica nanoparticles were developed and demonstrated fast breakability upon incubation with singlet oxygen.

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The purpose of this study was to explore the perceived impact of critical reflection on my cultural competence and practice of culturally responsive caring as a high school choral director. Caring educators establish trusting relationships with students that support them as teachers in identifying their strengths and interests, then employ that knowledge to develop student-centric curricula that generate opportunities for student success (Gay, 2018; Hendricks, 2018; Noddings, 2012). This practice is what Geneva Gay (2018) termed culturally responsive teaching. Gay (2018) also asserted, however, that a teacher cannot not claim to nurture caring relationships without accompanying cultural awareness. Considering ongoing and increasing social and political tensions that lead to societal divides in the United States, educators could benefit from practicing awareness so they can facilitate learning environments in which students are challenged, courageous, and inspired to explore their identities in caring environments. The pursuit of such cultural awareness, competence, and humility demands ongoing, authentic critical reflection—a vulnerable and arduous practice (Howard, 2003). This autoethnographic study considers literature positing that caring relationships in education demand profound and intentional cultural competence. It explores critical reflection as a means for developing such competence. This is an in-depth investigation into my pursuit of a culturally responsive caring practice as a high school choral director and product of the community in which I teach. The implications of this study describe my “cultural experience as it is particularly—not generally—lived” (Adams, et al., 2015, p. 41). The resulting narrative may encourage further research and empower educators and teacher educators to commit to a similar critically reflective practice that can lead to an authentic practice of culturally responsive caring.