Exploring the Macromolecular Frontier: Determining Stereochemical Effects in Strained Poly(alkenamer)s and Utilizing Auger Electron Spectroscopy to Evaluate Synthetic Polymers

Department of ChemistryThe utilization of synthetic methods to introduce specific functional groups into a monomer provides just a glimpse at the possibilities that exist with the cohesion of organic and polymer chemistry. This dissertation introduces the synthetic steps taken to synthesize small molecules containing a diester substituted cyclobutane scaffold and their usage as a monomer in ring opening metathesis polymerization (ROMP) reactions. The resulting polymers exhibited different thermal properties, which were traced back to originating from differences in the stereochemistry of the functional groups. In addition, multi-block copolymers with the block components only differing in the stereochemistry of the diester functional groups were successfully synthesized and found to undergo phase separation upon reaching a threshold molecular weight. Finally, attempts at degradation of the polymer through irradiation of the cyclobutyl groups will be shown and discussed. Although research into the synthesis and application of new polymers continues to grow, being able to analyze the underlying causes for why certain polymers exhibit certain properties is just as important. Analytical techniques, such as nuclear magnetic resonance (NMR) spectroscopy and size exclusion chromatography (SEC) provide polymer chemists with a wealth of knowledge towards characterizing polymers. However, these techniques become much more limited with insoluble polymers. Thus, the second half of this dissertation introduces the use of X-ray induced Auger electron spectroscopy (XAES) to ascertain the hybridization states of synthetic polymers containing carbons with differing degrees of sp-, sp2- and sp3-hybridization states as well as heteroatoms. For comparison, a series of related small molecules was also studied. Linear correlations were observed and a universal calibration method for quantifying the average hybridization states of a wide variety of synthetic polymeric materials is offered. Being able to determine the hybridization state of synthetic polymers provides polymer and analytical chemists with another tool towards improving and synthesizing polymers with unique properties.clos

Validity of Wearable Activity Monitors for Estimation of Resting Energy Expenditure in Adults

• Wearable accelerometers have become the standard method for assessing physical activity for both individuals and field-based research [1]. These new devices allow consumers to have the ability to estimate total energy expenditure and track it over time. • Resting Energy Expenditure plays a critical role in estimating daily total energy expenditure as it contributes 60-70% of total energy expenditure [2,3]. • Little to no information is available to substantiate the validity of these consumer-based activity monitors under free-living conditions

Using Sensewear Armband and Diet Journal to Promote Adolescents\u27 Energy Balance Knowledge and Motivation

Purpose: Educating adolescents about energy balance (EB) is essential for effective weight control. This study utilized the Sensewear (SWA) armband and a diet journal to promote adolescents\u27 EB knowledge and motivation. Methods: Ninety sixth graders were randomly assigned into the experimental group (n = 46) who utilized SWA and diet journal for 7 consecutive days or the control group (n = 44) who did not. Both groups were pre-and post-measured on EB knowledge, situational interest, and weight. The experimental group was tracked on motivation effort, energy expenditure (EE), and energy intake (EI). Results: EB knowledge significantly increased and situational interest remained stable (except for total interest and enjoyment) over time, but these changes did not favor the experimental group. Situational interest and motivation effort were correlated with EE, EI, and/or EB. Conclusion: Tracking EB using the SWA and diet journal is motivating but has limited efficacy in promoting adolescents\u27 EB knowledge. Using these two tools as educational technology in conjunction with a focused, systematic, and educational approach has the potential to leverage adolescents\u27 EB knowledge, motivation, as well as behaviors for living an energy-balanced lifestyle

Wasserstein Geodesic Generator for Conditional Distributions

Generating samples given a specific label requires estimating conditional distributions. We derive a tractable upper bound of the Wasserstein distance between conditional distributions to lay the theoretical groundwork to learn conditional distributions. Based on this result, we propose a novel conditional generation algorithm where conditional distributions are fully characterized by a metric space defined by a statistical distance. We employ optimal transport theory to propose the \textit{Wasserstein geodesic generator}, a new conditional generator that learns the Wasserstein geodesic. The proposed method learns both conditional distributions for observed domains and optimal transport maps between them. The conditional distributions given unobserved intermediate domains are on the Wasserstein geodesic between conditional distributions given two observed domain labels. Experiments on face images with light conditions as domain labels demonstrate the efficacy of the proposed method

Calibration of Built-in Accelerometer Using a Commercially Available Smartphone

Wearable trackers that detect sleep offer users a way to track their sleep quality and patterns without the use of expensive equipment. Few studies have tested the validity of these trackers on sleep measure. PURPOSE: To examine the validity of the Actigraph GT9X (AG), SenseWear Mini Armband (SW), Basis Peak (BP), Fitbit Charge HR (FB), Jawbone UP3 (JU), and Garmin Vivosmart (GV) for estimating sleep variables as compared with a sleep diary. METHODS: 78 healthy individuals participated in the study. Group 1 (n= 38) and wore the AG, SW, BP, and FB or Group 2 (n = 40) and wore the AG, JU, and GV. Monitors were worn on the non-dominant arm for 3 nights and a sleep log was completed. Sleep variables were total sleep time (TST), time in bed (TIB), sleep efficiency (SE), and wake after sleep onset (WASO). Pearson correlation, mean absolute percentage errors (MAPE), equivalence testing, Bland-Altman plots, and ANOVA were used to assess validity compared with the diary. RESULTS: Overall, monitors that showed the greatest correlation with the sleep diary for TST were the JU and FB (effect size= 0.09 and 0.23, respectively). The greatest correlation with the sleep diary for TIB was seen with the SW, GV, and JU (effect size= 0.09, 0.16, and 0.07, respectively). SE and WASO showed very poor correlation with the log. Measures for equivalence testing confirmed the success of the JU, SW, FB, and GV for measureing TIB and TST. CONCLUSION: The FB, SW, JU, and GV could be valid measure of TST and TIB. The monitors are not valid regarding wake times during sleep. Further research is needed to validate these monitors with polysomnography

Examination of Different Accelerometer Cut-Points for Assessing Sedentary Behaviors in Children

Background: Public health research on sedentary behavior (SB) in youth has heavily relied on accelerometers. However, ithas been limited by the lack of consensus on the most accurate accelerometer cut-points as well as by unknown effectscaused by accelerometer position (wrist vs. hip) and output (single axis vs. multiple axes). The present study systematicallyevaluates classification accuracy of different Actigraph cut-points for classifying SB using hip and wrist-worn monitors andestablishes new cut-points to enable use of the 3-dimensional vector magnitude data (for both hip and wrist placement).Methods: A total of 125 children ages 7–13 yrs performed 12 randomly selected activities (from a set of 24 differentactivities) for 5 min each while wearing tri-axial Actigraph accelerometers on both the hip and wrist. The accelerometer datawere categorized as either sedentary or non-sedentary minutes using six previously studied cut-points: 100counts-per-minute (CPM), 200CPM, 300CPM, 500CPM, 800CPM and 1100CPM. Classification accuracy was evaluated with Cohen’s Kappa(k) and new cut-points were identified from Receiver Operating Characteristic (ROC).Results: Of the six cut-points, the 100CPM value yielded the highest classification accuracy (k = 0.81) for hip placement. Forwrist placement, all of the cut-points produced low classification accuracy (ranges of k from 0.44 to 0.67). Optimal sedentarycut-points derived from ROC were 554.3CPM (ROC-AUC of 0.99) for vector magnitude for hip, 1756CPM (ROC-AUC of 0.94)for vertical axis for wrist, and 3958.3CPM (ROC-AUC of 0.93) for vector magnitude for wrist placement.Conclusions: The 100CPM was supported for use with vertical axis for hip placement, but not for wrist placement. The ROC-derived cut-points can be used to classify youth SB with the wrist and with vector magnitude data

Comparisons of prediction equations for estimating energy expenditure in youth

Objectives The purpose of this study was to compare the validity of Actigraph 2-regression models (2RM) and 1-regression models (1RM) for estimation of EE in children. Design The study used a cross-sectional design with criterion estimates from a metabolic cart. Methods A total of 59 children (7–13 yrs) performed 12 activities (randomly selected from a set of 24 activities) for 5 min each, while being concurrently measured with an Actigraph GT3X and indirect calorimetry. METRMR (MET considering one\u27s resting metabolic rate) for the GT3X was estimated applying 2RM with vector magnitude (VM2RM) and vertical axis (VA2RM), and four standard 1RMs. The validity of the 2RMs and 1RMs was evaluated using 95% equivalence testing and mean absolute percent error (MAPE). Results For the group-level comparison, equivalence testing revealed that the 90% confidence intervals for all 2RMs and 1RMs were outside of the equivalence zone (range: 3.63, 4.43) for indirect calorimetry. When comparing the individual activities, VM2RM produced smaller MAPEs (range: 14.5–45.3%) than VA2RM (range, 15.5–58.1%) and 1RMs (range, 14.5–75.1%) for most of the light and moderate activities. Conclusions None of the 2RMs and 1RMs were equivalent to indirect calorimetry. The 2RMs showed smaller individual-level errors than the 1RMs