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Physically associated hydrogels (PHs) capable of reversible transitions between solid and liquid‐like states have enabled novel strategies for 3D printing, therapeutic drug and cell delivery, and regenerative medicine. Among the many design criteria (e.g., viscoelasticity, cargo diffusivity, biocompatibility) for these applications, engineering PHs for extrudability is a necessary and critical design criterion for the successful application of these materials. As the development of many distinct PH material systems continues, a strategy to determine the extrudability of PHs a priori will be exceedingly useful for reducing costly and time‐consuming trial‐and‐error experimentation. Here, a strategy to determine the property–function relationships for PHs in injectable drug delivery applications at clinically relevant flow rates is presented. This strategy—validated with two chemically and physically distinct PHs—reveals material design spaces in the form of Ashby‐style plots that highlight acceptable, application‐specific material properties. It is shown that the flow behavior of PHs does not obey a single shear‐thinning power law and the implications for injectable drug delivery are discussed. This approach for generating design criteria has potential for streamlining the screening of PHs and their utility in applications with varying geometrical (i.e., needle diameter) and process (i.e., flow rate) constraints.

 

Research Experience for Teachers (RET) programs have been placing K-12 teachers in university research labs for almost three decades (Pop et al., 2010). However, the long-term impacts are rarely explored. This paper summarizes data from a survey study of 135/158 teachers (88% response rate) who participated in Stanford University’s RET programs between 2005 and 2017. The purpose of the study was to gauge the lasting impact of RET, if any, on teacher retention and classroom and professional practices. The data strongly suggest that participants gain long-lasting personal and professional benefits from participation--value that seems to be especially magnified for mid- to late-career teachers who are well established in their teaching practices but committed to continuous improvement. Furthermore, if the self-reports are accurate, these results would presumably also accrue to teachers’ students. Findings are attributed to the efficacy of the RET model. The authors argue for a nationwide evaluation of the efficacy of RET for teacher retention and professional development.