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The article offers step-by-step instructions for a practical approach to teaching introductory thermodynamics.

The sales potential of cosmetic products is greatly determined by skin feel and skin sensory performance. To please the target audience, it is important to gather information about consumers' perception of products' sensory characteristics. In this study, six different emulsions were formulated. Samples represented three different types of emulsions, including steric-stabilized oil-in-water (O/W), liquid crystal-stabilized O/W, and water-in-oil emulsions, providing different skin feel and aesthetics. Emulsions within the same group differed in the emollients, providing similar sensory attributes. The aim was to have 50 consumers evaluate the emulsions' sensory characteristics. Using a check-all-that-apply (CATA) survey, consumers provided information about their perception of appearance, rub-out, pick-up, and afterfeel. Consumers effectively discriminated between the emulsions. Statistical analysis showed significant differences for 15 sensory attributes in the before, during, and after phases. Our findings suggest that emulsifiers, and not emollients, have the dominant role in determining the aesthetics of a skin care emulsion, similar to previous findings. The fact that untrained consumers provided similar results as trained panelists suggests the validity of the CATA survey and its reliability as a screening tool in the product development process. CATA questions may serve as a viable complimentary to descriptive sensory analysis performed by trained panelists.

Gadolinium metal-organic framework (Gd MOF) nanoparticles are an interesting and novel class of nanomaterials that are being studied as a potential replacement for small molecule positive contrast agents in magnetic resonance imaging (MRI). Despite the tremendous interest in these nanoscale imaging constructs, there are limitations, particularly with respect to controlling the particle size, which need to be overcome before these nanoparticles can be integrated into in vivo applications. In an effort to control the size, shape, and size distribution of Gd MOF nanoparticles, hydrotropes were incorporated into the reverse microemulsion synthesis used to produce these nanoparticles. A study of how hydrotropes influenced the mechanism of formation of reverse micelles offered a great deal of information with respect to the physical properties of the Gd MOF nanoparticles formed. Specifically, this study incorporated the hydrotropes, sodium salicylate (NaSal), 5-methyl salicylic acid, and salicylic acid into the reverse microemulsion. Results demonstrated that addition of each of the hydrotropes into the synthesis of Gd MOFs provided a simple route to control the nanoparticle size as a function of hydrotrope concentration. Specifically, Gd MOF nanoparticles synthesized with NaSal showed the best reduction in size distributions in both length and width with percent relative standard deviations being nearly 50% less than nanoparticles produced via the standard route from the literature. Finally, the effect of the size of the Gd MOF nanoparticles with respect to their MRI relaxation properties was evaluated. Initial results indicated a positive correlation between the surface areas of the Gd MOF nanoparticles with the longitudinal relaxivity in MRI. In particular, Gd MOF nanoparticles with an average size of 82 nm with the addition of NaSal, yielded a longitudinal relaxivity value of 83.9 mM⁻¹ [Gd³⁺] sec⁻¹, one of the highest reported values compared to other Gd-based nanoparticles in the literature to date.