Electrospray Deposition of Polyvinylidene Fluoride (PVDF) Microparticles: Impact of Solvents and Flow Rate

Polymeric microparticles have been shown to have great impacts in the area of drug delivery, biosensing, and tissue engineering. Electrospray technology, which provides a simple yet effective technique in the creation of microparticles, was utilized in this work. In addition, altering the electrospray experimental parameters such as applied voltage, flow rate, collector distance, solvents, and the polymer-solvent mixtures can result in differences in the size and morphology of the produced microparticles. The effects of the flow rate at (0.15, 0.3, 0.45, 0.6, 0.8, and 1 mL/h) and N, N-Dimethylformamide (DMF)/acetone solvent ratios (20:80, 40:60, 60:40, 80:20, 100:0 v/v) in the production of polyvinylidene fluoride (PVDF) microparticles were studied. Scanning electron microscopy (SEM) was used to observe changes in the morphology of the microparticles, and this revealed that a higher acetone to DMF ratio produces deformed particles, while flow rates at (0.3 and 0.45 mL/h) and a more optimized DMF to acetone solvent ratio (60:40 v/v) produced uniform spherical particles. We discovered from the Raman spectroscopy results that the electrosprayed PVDF microparticles had an increase in piezoelectric β phase compared to the PVDF pellet used in making the microparticles, which in its original form is α phase dominant and non-piezoelectric

Examining the association between perceived discrimination and heart rate variability in African Americans.

Previous research attempting to delineate the role of discrimination in racial/ethnic disparities in hypertension has focused largely on blood pressure, which is chiefly governed by the sympathetic branch of the autonomic nervous system. Consequently, few studies have considered the role of the parasympathetic branch and particularly its regulation of the heart via the vagus nerve

Vagally mediated heart rate variability, stress, and perceived social support: a focus on sex differences

Higher vagally mediated heart rate variability (vmHRV), reflecting vagal activity as indexed by heart function and lower stress vulnerability, is associated with higher perceived social support. Seeking social support is an adaptive stress response, and evolutionary theories suggest that females use this strategy more than males. The current study investigated the hypothesis that higher vmHRV is related to higher perceived social support under conditions of higher, relative to lower, stress, and that this association is most prominent in females. A healthy student sample (n = 143; 82 males, 61 females; mean age 19.9) completed the short version of the Medical outcomes study social support survey (MOS) and the Perceived stress scale (PSS). Activity in the high frequency band of heart rate variability (HF-HRV), deducted from five-minute resting electrocardiogram (ECG) recordings, indexed vmHRV. A moderation analysis was conducted, with PSS and sex as moderators of the association between vmHRV and MOS. Statistical effects were adjusted for age, education, physical activity, body mass index (BMI), alcohol and drug use, ECG-derived respiration (EDR), and mean heart rate. Higher PSS scores moderated the association between vmHRV and MOS in females but not males. Lower PSS scores did not moderate the relation between vmHRV and MOS. This suggests that higher vmHRV is associated with higher perceived social support under conditions of higher stress in females but not males, consistent with evolution of different stress management strategies in the sexes. The results may have implications for individualized intervention strategies for increasing vmHRV and perceived social support.publishedVersio

Attachment insecurity, heart rate variability, and perceived social support in a diverse sample of young adults

Psychological and physical factors are robustly associated with perceived social support. Drawing from the literature on attachment style in adults and psychophysiology, we examined the possibility that the interaction of attachment insecurity and resting heart rate variability (HRV) was associated with perceived social support in a diverse sample of young adults living in the U.S (N = 145, Mage = 20.45) that was majority Latino (n = 77). Analyses revealed three key findings. First, in the overall sample, attachment avoidance and attachment anxiety were negatively associated with perceived social support, but in the Latino sample, only attachment avoidance was negatively associated with perceived social support. Second, HRV was not associated with perceived social support in the overall sample nor in the Latino sample. Third, attachment insecurity and HRV interacted to predict perceived social support only in the Latino sample such that, for those with lower levels of HRV, attachment anxiety was positively associated with perceived social support. This study underscores the importance of examining both psychological and physiological processes with careful consideration of ethnicity/culture in order to better understand perceived social support

Rumination Moderates the Association Between Resting High-Frequency Heart Rate Variability and Perceived Ethnic Discrimination

Williams, D. P., Pandya, K. D., Hill, L. K., Kemp, A. H., Way, B. M., Thayer, J., & Koenig, J. (2017). Rumination Moderates the Association between Resting High-Frequency Heart Rate Variability and Perceived Ethnic Discrimination. Journal of Psychophysiology, 1–10. http://doi.org/10.1027/0269-8803/a00020

A Histological Study of Temperature Effects on the Testis of the Fowl

94 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1955.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Interactions of Heart Rate Variability and Gender on Cognitive Performance

Psychology: 3rd Place (The Ohio State University Denman Undergraduate Research Forum)The study of reaction time to attention evoking stimuli is one to the oldest, yet consistently used paradigms in cognitive psychology. One variation of this paradigm is the Simon Effect task, during which individuals must respond to a stimuli that is consistent (congruent) or inconsistent (incongruent) with positioning. Interestingly, research has suggested that an index of cardiovascular health and flexibility (Heart Rate Variability|HRV) may predict performance on cognitive tasks such as the Simon Effect. This work suggests that communication between the heart and brain may serve much more complex functions than just heart rate regulation. In the present study we sought to support this notion using this attentional task. We predicted that individuals with higher resting HRV would show better performance on the cognitive task. Continuous heart rate data was collected using an exercise heart rate monitor (i.e. Polar watch) from 18 participants who completed a resting baseline period during which they sat quietly in a laboratory room, the Simon Task, and a recovery period. HRV was calculated for the baseline period of each participant; reaction times were computed for congruent/incongruent trials of the Simon Task. Means were compared using a factorial Analysis of Variance, First obtaining the median value for resting HRV and classified participants as either High HRV or Low HRV at baseline based on their position above or below the median; second, looking for potential gender differences in task performance. Analyses revealed a significant interaction between gender and HRV groups; males with High baseline HRV displayed slower mean reaction times whereas High HRV females exhibited faster reaction times. This pattern was reversed in the Low HRV groups for both genders. Our findings are partially consistent with previous research and further suggest that gender may be an important factor in using HRV as a predictor of cognitive performance.Academic Major: Psycholog