Fibers in biological scaffolds like fibronectin stiffen when they experience forces between cells. It will expose binding sites under contractile forces and then form disulfide bonds. This on-demand strain-stiffening is a desirable property in synthetic materials. Tran et.al. (2017) mimicked the “cryptic” design of fibronectin by copolymerizing thiol crosslinking sites with monomers containing poly (ethylene glycol) chains. When the PEG chain increased from 350 to 950 g/mol, the strains-stiffening became on-demand while the curing process extended from 3 hours to 15 hours. Extra steric hindrance brought by longer PEG chains caused decreasing mass transfer rates of cryptic sites while the same level of strain rate was introduced. I proposed to use stronger ultrasound mechanical perturbation so that higher strain rate can be induced, and the shielding effect brought by the PEG chain can be overcome more easily. Utilizing ultrasound as a stimuli has the potential to improve the gelation speed or achieve high mechanical performance while retain the long shelf life of the “cryptic” materials. To test this hypothesis, I synthesized “cryptic” polymer with aceto-acetoxy and primary amine as crosslinking sites such that, the only time limiting step is brought by the long PEG chain. This is because the bond formation reaction between these two reactive groups is rapid and spontaneous. When switching from weak to strong mechanical perturbation, the change in gelation speed owing to accelerated mass transfer between crosslinking sites can be easily compared. When the PEG chain is 300 Mw and 30 mol % crosslinking sites density, this “cryptic” polymer only showed strain-stiffening under ultrasound while strain under a rheometer was not able to overcome steric hindrance. Signs of chain scission appeared when the ultrasound amplitude was set at 75 %, but was counteracted by reducing amplitude mode over the time. The crosslinking was optimized by varying the ultrasound amplitude and intensity and a final mode of 1 hour 75 % amplitude, 0.5 hour 50 % amplitude and 3.5 hours 25% amplitude provided greatly improved on demand crosslinking. The estimated kinetic constant using this mode was two times higher than that of under simple shear strain. Through this study, I found that ultrasound can improve the curing time of this “cryptic” polymer system since it induces higher strain rate and expedite the mass transfer rate between crosslinking sites and optimizing the ultrasonic amplitude profile to limit chain scission provides improved crosslinking performance.

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Environment-responsive membranes were created by modification of a commerical polyvinylidene fluoride (PVDF) membrane support with a thermo-responsive hydrogel composed of poly N-vinyllactams cross-linked with bisacrylamide. The modified membranes were then characterized by their percentage mass gains as well as by their valve effect in response to changes in salt concentration. One set of membranes, with a large valve effect, was selected for highest retention of intermediately sized proteins was examined for ultrafiltration-based protein separation applications. A batch separation protocol featuring pulsed sample injection technique (PSIT) was then used to sieve single proteins and to fractionate a synthetic binary protein mixture and a synthetic ternary protein mixture with some success, demonstrating the potential of these environment-responsive membranes for use in multi-component separations. A second set of membranes, with a small valve effect, was selected for its ability to alter between hydrophobic and hydrophilic states under different environmental conditions and its potential in hydrophobic interaction membrane chromatography (HIMC) applications was successfully demonstrated by comparing against a benchmark membrane that is used successfully for HIMC applications in prior literature. / Thesis / Master of Applied Science (MASc)

IntelliDrive is an initiative developed by United States Department of Transportation (USDOT) that aims to enable safe, interoperable networked wireless communications among vehicles, the infrastructure, and passengers' personal communications devices. IntelliDrive technology has the ability to provide data that would be helpful in enhancement of the existing traffic management applications. IntelliDrive data has attributes that cannot be measured using traditional surveillance technology and which can be used for the development of new traffic management and traveler information applications. The traffic responsive plan selection (TRPS) mode of operation is used in coordinated traffic network to improve the performance of the system. This mode of operation has the ability to implement the best possible timing plan for the existing traffic conditions by switching between timing plans. The data from IntelliDrive technology can be utilized in the traffic responsive mode to improve the system performance by reducing the overall delay in the system. This paper proposes a system that can be used to integrate the data obtained from the IntelliDrive technology to the traffic responsive mode of operation. The proposed method utilizes the number of stops and delay of the vehicles in an intersection as a basis for the implementation of the best timing plan for the prevailing traffic condition. The study shows that using the IntelliDrive based TRPS results in the selection of the traffic plan that minimizes the delay of the system and thus results in better system performance compared to the traditional traffic responsive mechanism. / Master of Science

This thesis investigates culturally responsive teaching in the context of environmental education (EE) and is composed of an introduction (Chapter 1), one study intended for eventual publication (Chapter 2), and a personal reflection (Chapter 3). The introduction provides a brief overview of EE and explains why the topics of study included in this thesis are important to address. For Chapter 2, I conducted interviews to understand how environmental educators characterize culturally responsive EE, how they practice it, and what they identify are the key catalysts and challenges to providing culturally responsive EE. The results of this study indicate the importance of a multifaceted approach that incorporates EE content, educator practices, organizational practices, and a critically reflexive mindset. In Chapter 3, my personal reflection considers themes that were woven throughout the work, time, and thought spent on this project and as a master's student at Virginia Tech. This work is meant to provide ideas and guidance for EE practitioners as they seek out approaches for increasing relevance in EE programs, uplift equitable practices in the EE field, and progress along their journeys to awareness and action. / Master of Science / This study explores the framework for culturally responsive teaching in the context of environmental education (EE). Recognizing that the field has fallen short of providing relevant EE programming for students from communities who have been historically excluded from nature, practitioners seek education strategies that resonate with these groups. Terms such as culturally relevant and culturally responsive are touted as methods for reaching diverse learners on EE programs, but the field lacks clearly defined practices for implementing these approaches. This study examines culturally responsive teaching with the objective of identifying culturally responsive practices to increase the relevance and meaning of EE programs for the diversity of youth across the United States. We conducted interviews with EE educators and managers to answer main research questions: (1) How do EE practitioners characterize culturally responsive EE; (2) How do practitioners practice culturally responsive EE; and (3) What are key catalysts and challenges to being culturally responsive in EE? These questions seek to understand how EE practitioners achieve relevance and extend inclusion for more equitable EE programs. We explored ways that culturally responsive EE may be considered, integrated, and supported at the program content level, program delivery level, and the organizational level. This paper builds off of important work being done in EE research and by EE practitioners in the field to develop more inclusive programs and practices that reflect diverse experiences of learners.

This qualitative study focused on the need for culturally responsive teaching within the southern Appalachian cultural setting. The specific components of this approach to teaching were based on research findings, theoretical claims from proponents of culturally responsive teaching (e.g. Gloria Ladson-Billings and Geneva Gay), and experiences and personal narratives of educators working with students in southern Appalachia. The purpose of this study was to identify aspects of culturally responsive teaching within the Southern Appalachian context by observing instruction and curriculum that sustained the cultural competence of southern Appalachian students and empowered them. As the researcher, I also studied my own efforts as a teacher educator with southern Appalachian roots who was preparing preservice teachers to acquire the knowledge, attitudes and skills to practice culturally responsive teaching. Through narrative inquiry, the study focused on the experiences of an elementary teacher, an elementary principal, and a preservice teacher. The study was conducted within three settings (Holbrook Elementary, Central Elementary and Appalachia College) over a total period of three years. Data collection methods included interviews, observations, participation in school events, fieldnotes, videotapes, photographs, a participant’s journal and other artifacts. The findings identified practices that promoted culturally responsive teaching for southern Appalachia such as including the Appalachian culture in the curriculum, demonstrating caring, building learning communities, and connecting school to home and community by using the cultural backgrounds of southern Appalachian students as conduits for teaching them more effectively. Four characteristics of culturally responsive educators were presented: culturally responsive teaching takes skill; culturally responsive teaching takes inquiry; culturally responsive teaching is a moral craft; and culturally responsive teaching is a way of life, not just a job. / Ph. D.

This thesis presents a pedagogical framework for understanding dynamic Parametricism within the new media culture. As indicated by the title, 'Appliance Architecture in the Invisible College: a Pedagogical Text', this paper will serve two purposes. First, appliance architecture will construct the theoretical framework that will provide the context for the four case studies presented within this thesis: an interview with Rob Ley, designer of the Reef Project; the design and development of the Eclipsis Screen for the Solar Decathlon house, Lumenhaus; the development of an architectural robotics design laboratory, Prototyping in Architectural Robotics for Technology-enriched Education (PARTeE); and workshop > no.1, a physical computing workshop held at the College of Architecture + Urban Studies (CAUS). Second, the invisible college will serve as a pedagogical framework for teaching dynamic Parametricism within appliance architecture. The invisible college will explore the emergent design typologies developed through the PARTeE laboratory's first year and will culminate in the application of the teaching methodologies used for the physical computing workshop. The following serves to establish the architectural discourse within which 'Appliance Architecture in the Invisible College' is embedded. In the broadest sense, this discourse is that of kinetic architecture. The word 'kinetic' is used to denote motion, or the act or process of changing position of over time, where time is the unit of measurement or relativity. The 'appliance' is defined as any consumer object or assembly with embedded intelligence; it does not shy away from the modern connotation of objects such as a coffee maker, refrigerator or iPod. The appliance as an assembly, therefore, presents a part-to-whole relationship that is understood through GWF Hegel's organic unity, which states: 'everything that exists stands in correlation, and this correlation is the veritable nature of every existence. The existent thing in this way has no being in its own, but only in something else, just as the whole would not be what it is but for the existence of its parts, so the parts would not be what they are but for the existence of the whole' (Leddy, 1991). It is this part-to-whole relationship which provides an understanding of the emergent typologies which structure the foundation for learning within the invisible college. / Master of Architecture