This work details the design and testing of affinity membrane adsorbers for lectin purifications that incorporate glucose-containing glycopolymers. It is the selective interaction between the sugar residues of the glycopolymer and the complementary carbohydrate-binding domain of the lectin that provides the basis for the isolation and purification of lectins from complex biological media. The design approach used in these studies was to graft glycopolymer ‘tentacles’ from macroporous regenerated cellulose membranes by atom transfer radical polymerization. As shown in earlier studies, this design approach can be used to prepare high-productivity membrane adsorbers. The model lectin, concanavalin A (conA), was used to evaluate membrane performance in bind-and-elute purification, using a low molecular weight sugar for elution. The membrane capacity for binding conA was measured at equilibrium and under dynamic conditions using flow rates of 0.1 and 1.0 mL/min. The first Damkohler number was estimated to relate the adsorption rate to the convective mass transport rate through the membrane bed. It was used to assess whether adsorption kinetics or mass transport contributed the primary limitation to conA binding. Analyses indicate that this system is not limited by the accessibility of the binding sites, but by the inherent rate of adsorption of conA onto the glycopolymer.

This paper describes the surface modification of macroporous membranes using ATRP (atom transfer radical polymerization) to create cation-exchange adsorbers with high protein binding capacity at high product throughput. The work is motivated by the need for a more economical and rapid capture step in downstream processing of protein therapeutics. Membranes with three reported nominal pore sizes (0.2, 0.45, 1.0 μm) were modified with poly(3-sulfopropyl methacrylate, potassium salt) tentacles, to create a high density of protein binding sites. A special formulation was used in which the monomer was protected by a crown ether to enable surface-initiated ATRP of this cationic polyelectrolyte. Success with modification was supported by chemical analysis using Fourier-transform infrared spectroscopy and indirectly by measurement of pure water flux as a function of polymerization time. Uniformity of modification within the membranes was visualized with confocal laser scanning microscopy. Static and dynamic binding capacities were measured using lysozyme protein to allow comparisons with reported performance data for commercial cation-exchange materials. Dynamic binding capacities were measured for flow rates ranging from 13 to 109 column volumes (CV)/min. Results show that this unique ATRP formulation can be used to fabricate cation-exchange membrane adsorbers with dynamic binding capacities as high as 70 mg/mL at a throughput of 100 CV/min and unprecedented productivity of 300 mg/mL/min.

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This paper presents a quantitative and qualitative study for discovering how written reflective exercises following in-class prediction activities enhance learning gains in a heat and mass transfer course for chemical engineering undergraduate students. The primary purpose of this research is to determine if and to what extent written reflection plays a role in adjusting commonly-held misconceptions students have about heat and mass transfer. To study this, three 30-minute prediction activities were planned throughout a ten-week course. The study participants included two sections of a course with approximately 20 junior-level chemical engineering students each. Based on their course section, students were broken into two groups. One group was asked to complete a follow-up reflection assignment after each prediction activity, guiding them through the reflective process, while the other group completed no structured follow-up reflection activity. The HECI (Heat and Energy Concept Inventory) was administered to students of all sections at the start and the end of the course. The HECI was used to evaluate learning gains. Archived data from classes with no prediction activities and no reflection activities served as a control group. Correlations between quantitative assessment performance and student group (prediction activities and practicing reflection, prediction activities only, no prediction and no reflection) are discussed. To explore if the quality of reflection is related to learning gains, student reflections were ranked according to a validated rubric and compared with data on learning gains. Additionally, to further understand how students' perception of learning is affected by these activities, a focus group of 5 students was organized and interviewed in a semi-structured format after the conclusion of the course. Key insights from the qualitative interviews are discussed. The goal of this work in progress is to aid in directing the role of prediction and reflection activities in future courses. IntroductionThe motivation for this work is driven by the conclusions that that even after successful completion of college-level engineering courses, some students still hold common misconceptions about heat and mass transfer. This has been documented in the form of postinstruction assessments, such as concept inventories, that target assessing conceptual knowledge. Beyond calculations and problem-solving, conceptual knowledge seems particularly difficult to adjust using traditional classroom techniques. This study explores the use of reflective activities in combination with prediction activities to better understand if and how reflection plays a role in shifting conceptual knowledge of heat and mass transfer.The theoretical foundations for this study include literature on conceptual change, inductivelearning as a form of active-learning, and reflection. This literature review will give a brief overview of conceptual change and inductive-learning, but will focus on reflection, particularly in the contex...

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