Syracuse University
Syracuse University Research Facility and Collaborative EnvironmentNot a member yet
20376 research outputs found
Sort by
THERMODYNAMICS AND SHEAR FLOW DYNAMICS OF BLOCK COPOLYMER MORPHOLOGIES IN SOLUTION
Get PDFBlock copolymers (BCPs) have been a focal point of research for several decades. They have been engineered to produce various morphologies by altering the combinations of chemically distinct polymer segments that interact selectively with their environment, such as in aqueous or organic solvents, or within a polymer matrix. The ability to tailor morphological features by manipulating polymer chain length, composition, and monomer chemistry has led to applications in advanced material manufacturing, catalysis, emulsification, environmental remediation, targeted drug delivery, gene therapy, and medical diagnostics. Consequently, understanding the relationship between copolymer architecture and the self-assembled morphologies at equilibrium, the pathways of structure evolution and the stability of equilibrium structures to perturbations in environmental variables such as flow shear and temperature, is crucial for designing polymers for diverse applications. This study employs CGMD simulations, focusing on prototypical amphiphilic copolymers composed of Poly(Butadiene) (PB) and Poly(Ethylene Oxide) (PEO). The behavior of single polymer chains in aqueous solutions is investigated. The dependence of the radius of gyration and configurational relaxation time of the copolymers on chain length L and PB/PEO ratio are studied. The study then examines the self-assembly of PB-PEO diblock copolymers. Across varying copolymer compositions (L and PB/PEO ratio), a diverse phase portrait of emergent morphologies is observed, including simple structures such as spherical micelles, vesicles (polymersomes), bilayer lamellae, linear wormlike micelles, and tori, as well as complex forms like branched micellar networks and composite aggregates. The topological and compositional details of these morphologies are quantitatively characterized. Further, the energetic and entropic metrics underlying morphology selection are analyzed. The simulation results align well with experimental observations, offering insights into the mechanisms that render morphological diversity in amphiphilic copolymer systems. The study also investigates how structural changes occur with variations in concentration and temperature. Further, a mechanism of vesicle formation by water diffusion into a spherical micelle is discovered. The study further focuses on the mechanism of vesicle formation by the self-assembly of AB and BAB type BCPs, where A and B represent the hydrophilic (PEO) and hydrophobic (PB) segments, respectively. For AB BCPs, evolution follows the order of spherical and rod-like micelles, wormlike structures, lamellae, cavities, and vesicles. BAB BCPs first form interconnected copolymer networks, then deform to lamellar cages, ultimately transitioning into stable vesicles. Molecular reorganization at constant aggregation number to reduce solvent accessible surface area (SASA) and consequently the unfavorable hydrophobic interactions is a common motif of vesiculation. Subsequently, this work investigates the behavior of stable BAB vesicles under shear flow. Non-equilibrium molecular dynamics simulations reveal how unilamellar triblock copolymer vesicles respond to external hydrodynamic forces. Their deformation mode is affected by Weissenberg number Wi, defined as the ratio of the time scale of vesicle shape fluctuations to the inverse shear rate. For Wi \u3c 10, a spherical vesicle deforms into a flow-aligned ellipsoidal bilayer executing tank-treading motion. For Wi \u3e 10, pronounced variations in bilayer thickness and polymer extension manifest along the contour of the elongated vesicle, which breaks up into lamellar fragments. Below a critical strain, the deformed vesicle upon flow cessation returns to initial spherical morphology. However, for larger strains, structure reorganization after flow stoppage results in the formation of a Novel Equilibrated Shear-Induced Structure (NoESIS), in which two vesicles are connected by a dynamic molecular bridge which can accommodate additional layers of copolymers leading to a reduction in the polymer-solvent interface area. At even larger strains, the deformed vesicle breaks apart after flow cessation and eventually reorganizes into a smaller vesicle and a composite vesicular structure
EFFECTS OF PEER FEEDBACK AND SELF-FEEDBACK ON STUDENT LEARNING IN ASYNCHRONOUS ONLINE DISCUSSIONS
No full textFeedback plays an important role in the learning process. Peer feedback and self-feedback have become popular as two dominant feedback activities in online learning environments due to their efficiency and feasibility. However, previous studies have yielded inconsistent findings regarding their effectiveness, making it necessary to determine which feedback method is more effective in online learning environments. In this mixed methods study, the quantitative phase was conducted through a Latin square quasi-experimental design to compare the effects of peer feedback and self-feedback on students’ online learning performances in an asynchronous online discussion forum. Students’ perspectives on the two feedback activities were then collected through a 5-point Likert scale online survey. Voluntary Zoom interviews conducted during the qualitative phase were transcribed and analyzed to clarify and extend the experimental findings. Content analysis, between-subjects one-way analysis of variance (ANOVA), within-subjects one-way ANOVA, paired-samples t test, and thematic analysis were conducted to analyze the data. The results showed mixed effects of different feedback types on the quantity and quality of interactions, aligning with previous studies. The effectiveness of peer feedback and self-feedback is supported by their theoretical foundations and consistent with prior research emphasizing the benefits of both types across various academic settings. This suggests that integrating both peer feedback and self-feedback into asynchronous online discussions (AODs) can enhance students’ discussion performance in terms of quantity and quality. Overall, self-feedback proved to be more effective than peer feedback. This finding highlights the importance of considering the unique characteristics of each feedback type. Self-feedback and peer feedback have different cognitive, motivational, and emotional demands for students, each offering different advantages and disadvantages that need careful evaluation. Selecting the appropriate feedback type requires awareness of these benefits and limitations. Finally, timing, student characteristics, and feedback design can all impact feedback effectiveness. Based on the differences between self-feedback and peer feedback, and the factors impacting feedback effectiveness, it can be concluded that peer feedback tends to be more effective for students who have established a collaborative learning culture and foundation, as well as for those with a strong need for peer interaction. Self-feedback is particularly effective for non-traditional students who are generally older, more experienced, and possess strong abilities for self-assessment. Both peer feedback and self-feedback are more effective when conducted at the beginning of a course or when students are familiar with class routines and ready to engage. However, when students are under a heavy workload, both peer feedback and self-feedback can lose effectiveness. In addition, both peer feedback and self-feedback are more effective for tasks that require both quantity and rigor, thorough analysis that meets high-quality standards, and additional time for the feedback’s effects to take root. However, self-feedback is less effective for tasks requiring a high volume of contributions, as it lacks the external engagement found in peer feedback and is inherently focused on depth rather than quantity. The survey results indicated that students rated self-feedback higher than peer feedback in terms of fairness, usefulness, willingness to improve, and emotions, except for acceptance and satisfaction with design features; however, these differences were not statistically significant. The interview results indicated that students recognized the significance of feedback interventions in AODs and emphasized the benefits of integrating such feedback. They also appreciated the supportive scaffolding offered prior to their participation in feedback activities. In addition, students highlighted challenges associated with these feedback activities, aligning with our emphasis on the proper consideration of timing, student characteristics, and feedback design to ensure the effectiveness of feedback. This study enhanced our understanding of feedback in AODs, offering valuable insights to instructional designers and online instructors on the design and implementation
Authoritative Parenting Style Predicting Daily Frequency of Detrimental and Beneficial Food Intake and Physical Activity in Adolescents
Get PDFFrom New York to Yunnan: Comparative Perspectives on Poverty Alleviation Policies and Initiatives
Get PDF
Understanding Ourselves in Qualitative Research Through Collaborative Sense-making
No full textIn the fall of 2023, the iSchool at Syracuse University offered a new PhD course entitled IST 800 Information Studies Seminar: Qualitative Research Methods. This course was intended to teach students about various qualitative methods. A key part of the curriculum was centered on a discussion of how researchers are implicated by their epistemological and ontological positionality and how this awareness should inform their methodological decisions and analytical interpretations. As part of the course, students were asked to keep a weekly sense-making journal, which was intended as a routine medium through which students could reflectively engage with the various author claims, arguments, and philosophical perspectives that were raised in the course readings and shared class discussions. After the course ended, several of the students from the course embarked on a collaborative autoethnographic project to examine how their respective learnings about qualitative methodologies had shaped their individual research ontologies and epistemologies. This poster provides an overview of this collective analysis.
We argue that the reflexive nature of the course acted as a generative springboard for us (i.e., the students) to explore and question our values, sensitivities, and, ultimately, our worldviews; in tandem, the assigned sense-making memos gave us a chance to proactively develop our researcher positionalities. It is our hope that sharing the insights from this autoethnographic project will support other early career researchers in understanding how to critically engage their own positionality, and will provide information science educators inspiration for their own research methodology pedagogy