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Hydrogenation Hydrogenation O 0220 Catalytic Olefin Hydrogenation Using N-Heterocyclic Carbene-Phosphine Complexes of Iridium. -Novel complexes having a combination of phosphine and N-heterocyclic carbene ligands are found to be highly reactive towards the homogeneous catalytic hydrogenation of simple olefins, including hindered substrates. -(VAZQUEZ-SERRANO, L. D.; OWENS, B. T.; BURIAK*, J. M.; Chem.

Caffeine is a hydrate‐forming polymorphic crystalline compound that can exist in α, β, and hydrate forms. Phase transitions between hydrate and anhydrous forms of a crystalline ingredient, and related water migration, can create product quality challenges. The objective of this study was to determine the relative humidity (RH)–temperature phase boundary between anhydrous β‐caffeine and caffeine hydrate. The β‐caffeine→caffeine hydrate and caffeine hydrate→β‐caffeine RH–temperature transition boundaries were determined from 20 to 45 °C using a combination of water activity (aw) controlled solution and vapor‐mediated equilibration, moisture sorption, powder X‐ray diffraction, and Fourier‐transform infrared spectroscopy techniques. Two transition boundaries were measured: the β‐caffeine→caffeine hydrate transition boundary (0.835 ± 0.027 aw at 25 °C) was higher than the caffeine hydrate→β‐caffeine transition boundary (0.625 ± 0.003 aw at 25 °C). Moisture sorption rates for β‐caffeine, even at high RHs (>84% RH), were slow. However, caffeine hydrate rapidly dehydrated at low RHs (<30% RH) into a metastable transitional anhydrous state with a similar X‐ray diffraction pattern to metastable α‐caffeine. Exposing this dehydrated hydrate to higher RHs (>65% RH) at lower temperatures (20 to 30 °C) resulted in full restoration to a 4/5 caffeine hydrate. This transitional anhydrous state was unstable and converted to a less hygroscopic state after annealing at 50 °C and 0% RH for 1 day. It was postulated that the caffeine hydrate→β‐caffeine was the true β‐caffeine↔caffeine hydrate phase boundary and that β‐caffeine could be metastable above the caffeine hydrate→β‐caffeine transition boundary. These caffeine RH–temperature transition boundaries could be used for selecting formulation and storage conditions to maintain the desired caffeine crystalline form. Practical Application Caffeine can exist as either an anhydrous (without water) or hydrate (internalized water) crystalline state. The stability of each caffeine crystalline form is dictated by humidity (or water activity) and temperature, and these environmental stability boundaries for the caffeine crystalline forms are reported in this manuscript. Conversions between the two crystalline states can lead to deleterious effects; for example, the presence of caffeine hydrate crystals in a low water activity food (e.g., powder) could lead to the relocation of the water in caffeine to other ingredients in the food system, leading to unwanted water–solid interactions that could cause clumping and/or degradation.

Objectives Stress increases appetite for highly palatable foods and can affect decision-making. Thus, higher stress may interfere with the ability to eat intuitively and result in calorie intake that exceeds physiological needs, contributing to increased adiposity. To our knowledge this relationship has not been explored. Our objective was to examine the association between perceived stress and adiposity in midlife women and test whether intuitive eating (IE) mediates this relationship. Methods Data from a cross-sectional study of midlife women, 40–64 years of age (n = 113), conducted April 2017 to July 2019 was analyzed. Participants completed two in-person visits and self-reported questionnaires, including the Perceived Stress Scale and the Intuitive Eating Scale. Adiposity was assessed by dual energy x-ray absorptiometry. We examined the following subscales of the Intuitive Eating Scale as possible mediators: 1) unconditional permission to eat, 2) eating for physical rather than emotional reasons, and 3) reliance on internal hunger and satiety cues. We used structural equation modeling and bootstrap confidence intervals to examine mediation of intuitive eating through perceived stress and adiposity. Results The direct path from perceived stress to adiposity was not significant (Β = 0.07, p = .51) and indirect effects through the intuitive eating subscales were not significant. Higher perceived stress was associated with both lower reliance on internal hunger and satiety cues (Β = −0.02, p = .04) and lower eating for physical reasons (Β = −0.04, p = .003), and lower reliance on internal hunger and satiety cues was associated with higher adiposity (Β = −5.49, p &lt; .01). Eating for physical reasons was not associated with adiposity (Β = −1.38, p = .12) and unconditional permission to eat was not associated with perceived stress (Β = −0.006, p = .59) or adiposity (Β = 0.55, p = .63). Conclusions Though mediation was not present, lower reliance on hunger and satiety cues was independently associated with higher perceived stress and higher adiposity in this sample of midlife women. Given the association between higher perceived stress and lower intuitive eating, future research is warranted to examine possible physiological reasons explaining this relationship. Funding Sources Supported by funds from the College of Health Sciences at the University of Rhode Island.

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