We present the results of rotational coherence spectroscopy (RCS) experiments on jet-cooled naphthalene trimer. The RCS results, obtained by mass-selective, time-resolved ionization depletion, indicate that the species is an oblate symmetric top with rotational constants B = 167 ± 1 MHz and C = 141 ± 1 MHz. These constants are consistent with a cluster in which the long axes of three cyclically-arranged, symmetrically equivalent naphthalene moieties are parallel to one another and to the symmetry axis of the cluster. The distances between the centers of mass of the moieties in this structure are determined to be 4.925 ± 0.020 Å from the rotational constants. The results are consistent with ab initio and empirical force-field calculations of the species' structure (see Gonzalez and Lim, preceding Letter) and with the results of prior vibrational and vibronic spectroscopic studies.

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Fluid ingestion is necessary for life, and thirst sensations are a prime motivator to drink. There is evidence of the influence of oropharyngeal stimulation on thirst and water intake in both animals and humans, but how those oral sensory cues impact thirst and ultimately the amount of liquid ingested is not well understood. We investigated which sensory trait(s) of a beverage influence the thirst quenching efficacy of ingested liquids and the perceived amount ingested. We deprived healthy individuals of liquid and food overnight (> 12 hours) to make them thirsty. After asking them to drink a fixed volume (400 mL) of an experimental beverage presenting one or two specific sensory traits, we determined the volume ingested of additional plain, ‘still’, room temperature water to assess their residual thirst and, by extension, the thirst-quenching properties of the experimental beverage. In a second study, participants were asked to drink the experimental beverages from an opaque container through a straw and estimate the volume ingested. We found that among several oro-sensory traits, the perceptions of coldness, induced either by cold water (thermally) or by l-menthol (chemically), and the feeling of oral carbonation, strongly enhance the thirst quenching properties of a beverage in water-deprived humans (additional water intake after the 400 ml experimental beverage was reduced by up to 50%). When blinded to the volume of liquid consumed, individual’s estimation of ingested volume is increased (~22%) by perceived oral cold and carbonation, raising the idea that cold and perhaps CO2 induced-irritation sensations are included in how we normally encode water in the mouth and how we estimate the quantity of volume swallowed. These findings have implications for addressing inadequate hydration state in populations such as the elderly.

This study was designed to compare various salivary parameters between smokers and non-smokers and to determine the influence of a nicotine-containing chewing gum (used to aid in quit-smoking efforts) upon these same parameters. At the baseline examination, subjects were assigned to one of three groups: non-smokers who did not utilize any gum, smokers provided a nicotine-containing gum, and smokers provided a placebo gum. Saliva was collected from all subjects and analyzed for acidogenicity and buffer pH as well as for levels of thiocyanate, lactoperoxidase, lysozyme, lactoferrin, and secretory IgA. After 15 weeks of gum usage, saliva was again collected from each subject and the identical analyses performed. Significant differences were observed between smokers and non-smokers with regard to three parameters: The saliva of smokers contained greater concentrations of thiocyanate and lower concentrations of lactoferrin, at the baseline examination and after the 15-week test period. In addition, the CO content of alveolar air was higher in smokers at both examination periods. In contrast, the use of the nicotine gum per se had no effect on any of the test parameters.

One of the limitations of commingled recycled plastics is their low flexural modulus, resulting from both the linear nature of thermoplastics and the incompatibility of the polymer phases. The goal of this study was to increase the flexural modulus of commingled recycled plastics by the addition of small amounts of polyester that acted both as a compatibilizer and a crosslinking agent. I t was found that the increase in flexural modulus was caused by the unsaturated polyester acting as a filler, the improvement in compatibility of the phases, and the crosslinking of the commingled plastics. The increase was offset somewhat by a decrease in crystallinity of the phases.

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