2,711 research outputs found
Studies in Condensation Reactions
The mechanism of the Thermal Michael reaction, i.e., the condensation of a Mannich base with a compound containing an activated methylene group, has been studied and evidence has been obtained which corroborates the postulated reaction steps. The Mannich bases of both phenyl acetylene and beta-naphthol have been prepared and their condensation with cyclohexanone attempted. The former compound fails to react, while a dihydropyran, the hemiketal of (1-[2'-oxocyclohexylmethyl])-(2-hydroxy)-naphthalene is isolated in 85% yield from the reaction of the latter compound. The structures of the isomeric diMannich bases of acetone, [1,5-bis(dimethylamino)]-pentan-3-one and (1-dimethylamino)-(2-dimethylaminomethyl)-butan-3-one, and of the diMannich base of methyl ethyl ketone, [1,5-bis-(dimethylamino)]-(4-methyl)-pentan-3-one, have been corroborated using N.M.R. evidence and the synthesis of bridged bicyclic ketones has been attempted by their condensation with cyclopentanone. This method was only successful in the case of the gem-diMannich base, (1-dimethylamino)-(2-dimethylaminomethyl)-butan-3-one. The condensation product,(3-acetyl)-bicyclo[3,2,1]-octan-8-one, was identified by its physical data and the results of deuteration studies. The two (1,5)-diMannich bases condensed with two molecules of cyclo-pentanone to give [1,5-bis(2'-oxocyclopentyl)]-pentan-3-ones. The use of a solvent, ethylene glycol, in the Thermal Michael reaction has also been investigated. Unless there is a particular need for such a condition, it was concluded that the use of excess ketone as solvent is advisable. The mass-spectral fragmentation patterns of a series of ethylene ketals of 2[beta-benzyl-ethyl ]-cyclopentanones have been examined to determine the positions of substitution in the cyclopentanone rings. This may be applied as a general method to determine the orientation of attack, which this work confirmed to take place invariably at the least substituted position
The Association Between Sleep and Body Mass Index (BMI) in College Freshmen at Utah State University
Background: Obesity has become a major health problem with increasing prevalence in the United States. Cases of obesity have increased at alarming rates and have almost doubled over the past 40 years. During this same period of time, sleep duration for all age groups has significantly declined. Because sleep duration is a potential mediator of energy metabolism and body weight, it is an important aspect of health. An association between short habitual sleep time and increased body mass index (BMI) has been reported in large population studies for US young adults. Freshmen college students may encounter many environmental and emotional changes that may lead to sleep deprivation. Perhaps, it is sleep deficit within college freshmen that contributes to the phenomena of “The Freshmen 15”, which suggests that college freshmen often gain weight during their first year of college.
Objectives: The purpose of this study was to determine the relationship between sleep duration and body mass index (BMI) in a subset of college freshmen at Utah State University during their first academic year.
Methods: The “USU Freshmen Health Study” (PI: Heidi Wengreen, PhD, RD) provided all the data needed to study the relationship between sleep duration and BMI. As such, three data collections during the academic year of 2005-2006 were conducted for 186 college freshmen students, ages 18-19, at Utah State University. The data collections occurred during the beginning of fall semester, the end of fall semester, and the end of spring semester. Participants were asked to report an estimate of their average sleep duration for weekdays and weekends during each data collection period. BMI (kg/m2) was calculated based on measured weight and heights, which were measured during each of the three data collection periods.
Results: No significant changes in average sleep or average BMI were seen between each data collection for this population. Therefore, the overall mean duration of sleep was 7.33 hours per night while the mean BMI was 23.48.At baseline, shorter sleep duration was correlated with higher BMI among men but not women (p=.021 vs. p=.738). Average sleep duration was lowest in the first data collection compared to the second and third data collections (7.05 hours (SD=1.10), 7.42 hours (SD=1.12), 7.51 hours (SD=1.10), respectively), although these differences were not statistically significant.
Conclusion: This population of college freshmen students are not getting the recommended 8.5-9.25 hours of sleep, as outlined by the National Sleep Foundation for adolescents and teens (12-19 years of age). Sleep deprivation may be a potential risk factor for higher BMI at least among college freshmen males.Observed differences between men and women for sleep duration and its affect on BMI, may be the result of gender differences in physiology and hormonal regulation
The flock
5 p. l., [3]-266 p., 1 l.Describes the history and work of sheepherders in the San Joaquin Valley. They were a varied group of people from Spain, Mexico, France, Germany, and the Basque country. Describes their activities throughout the year. Includes illustrations by E. Boyd Smith.The coming of the flocks -- The sun in Aries -- A shearing -- The hireling shepherd -- The long trail -- The open range -- The flock -- The go-between -- The strife of the herdsmen -- Liers-in-wait -- The sheep and the reserves -- Ranchos Tejon -- The shade of the arrows
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