This report presents a summary of a meeting on assessment of course-based undergraduate research experiences (CUREs), including an operational definition of a CURE, a summary of research on CUREs, relevant findings from studies of undergraduate research internships, and recommendations for future research on and evaluation of CUREs.

This study investigates alginate-chitosan polyelectrolyte complexes (PECs) in the form of a film, a precipitate, as well as a layer-by-layer (LbL) assembly. The focus of this study is to fully characterize, using the complementary techniques of Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) in combination with solution stability evaluation, the interactions between alginate and chitosan in the PECs. In the FTIR spectra, no significant change in the band position of the two carbonyl vibrations from alginate occurs upon interaction with different ionic species. However, protonation of the carboxylate group causes a new band to appear at 1710 cm(-1), as anticipated. Partial protonation of the amine group of chitosan causes the appearance of one new band ( approximately 1530 cm(-1)) due to one of the -NH3+ vibrational modes (the other mode overlaps the amide I band). Importantly, the position of the two main bands in the spectral region of interest in partly protonated chitosan films is not dependent on the extent of protonation. XPS N 1s narrow scans can, however, be used to assess the degree of amine protonation. In our alginate-chitosan film, precipitate, and LbL assembly, the bands observed in the FTIR correspond to the species -COO- and -NH3+, but their position is not different from each of the single components. Thus, the conclusion of the study is that FTIR cannot be used directly to identify the presence of PECs. However, in combination with XPS (survey and narrow N 1s scans) and solution stability evaluation, a more complete description of the structure can be obtained. This conclusion challenges the assignment of FTIR spectra in the literature.

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The structural characterisation of high water content materials such as hydrogels is challenging due to the inherent properties of water that are dependent on conditions of temperature and pressure. Cryo-scanning electron microscopy (cryo-SEM) has potential to offer the most authentic insights into the native structure of polysaccharide hydrogels, due to the ability to freeze the sample under conditions where transparent vitreous ice is formed. The advantages, challenges and constraints of cryo-SEM in characterising the porous matrix of alginate hydrogels are considered in this tutorial paper through examples from our own studies. Recommendations are proposed for the minimum methodological information that is required from researchers as part of the publication of their studies of hydrogel samples to enable critical appraisal of their cryo-SEM images.