Barocaloric Effects in Dialkylammonium Halide Salts.

Barocaloric effects─solid-state thermal changes induced by the application and removal of hydrostatic pressure─offer the potential for energy-efficient heating and cooling without relying on volatile refrigerants. Here, we report that dialkylammonium halides─organic salts featuring bilayers of alkyl chains templated through hydrogen bonds to halide anions─display large, reversible, and tunable barocaloric effects near ambient temperature. The conformational flexibility and soft nature of the weakly confined hydrocarbons give rise to order-disorder phase transitions in the solid state that are associated with substantial entropy changes (>200 J kg-1 K-1) and high sensitivity to pressure (>24 K kbar-1), the combination of which drives strong barocaloric effects at relatively low pressures. Through high-pressure calorimetry, X-ray diffraction, and Raman spectroscopy, we investigate the structural factors that influence pressure-induced phase transitions of select dialkylammonium halides and evaluate the magnitude and reversibility of their barocaloric effects. Furthermore, we characterize the cyclability of thin-film samples under aggressive conditions (heating rate of 3500 K s-1 and over 11,000 cycles) using nanocalorimetry. Taken together, these results establish dialkylammonium halides as a promising class of pressure-responsive thermal materials.

"A Place to Be Heard and to Hear": the Humanities Collaboratory as a Model for Cross-College Cooperation and Relationship-Building in Undergraduate Research.

This article reports findings from a study of laboratory-styled humanities undergraduate research (UR) programming designed to increase access to this high-impact practice, better reaching historically excluded students and less visible institutions. The Humanities Collaboratory (HLAB) is a ten-week summer research program that emerged from the partnership of a research university and the area community college system. Aimed at actively addressing educational inequity, and the more specific lack of access humanities students have to impactful UR opportunities, HLAB offers an intensive humanities research experience to first-generation students, low-income students, and Students of Color currently enrolled in two-year colleges, HBCUs, MSIs, and HSIs. Since the program's creation in 2018, qualitative data collected from 50 participating students over three years of self-evaluations illustrates why HLAB presents a significant learning opportunity for students and highlights the critical importance of relationship-building in UR. Analyzing students' responses through the heuristic of communities of practice provides insight into a community-focused UR pedagogy that emphasizes relationality among students, mentors, and institutions. Students detail the importance of collaborative skill-building, opportunities for peer support, networking connections, and possibilities for more holistic personal growth in UR experiences. Our findings describing the benefits of relational UR signal the need for cooperative programming designs that increase access to undergraduate research for humanities students across institutions of higher education.