Understanding the Effect of Nanointerfaces on Nanostructure and Mechanical Properties of Semicrystalline Polymers Using Coarse-Grained Molecular Dynamic Simulations

Polymer crystallization is a classical problem of polymer research. Many synthetic and natural polymers take the semi-crystalline form. Crystallization of polymers is a complex process associated with the partial alignment of their molecular chains. The final physical properties of semicrystalline polymers are determined by the degree of crystallinity and the size and orientation of the crystallites (nano- to micro-sized crystalline regions). Although it has been studied for many years, we still lack a fundamental understanding of the types of factors that influence the semicrystalline structure and how the structure affects the final properties. It is difficult because crystalline polymers are far from thermodynamic equilibrium, and theories usually fall short of accurately describing the process. In addition, recent experimental studies indicate a multi-stage process where the polymer chains undergo several transitions before an overall crystalline phase is fully developed, making hands-on experiments alone challenging to study this phenomenon [1]. Nanofillers with characteristic sizes smaller than tens of nanometers have been used to enhance the mechanical properties of polymers. However, the specific effect of the nanointerfaces between nanofillers and polymer chains on the nanocomposite\u27s structural evolution and resulting mechanical properties remain largely elusive. This knowledge gap stems from two-fold challenges: (1) experimental techniques and characterizations have limited resolutions at the molecular level and nanoscale interface interactions, and (2) the involved spatial-temporal scales ranging from molecular chains, nanointerfaces, and microstructural evolutions are beyond the capability of any computational models or simulation techniques. Therefore, this project aims to understand the nano-fillers, interfaces, and microstructures in the mechanical properties of biopolymer-based nanocomposites, which have potential in diverse applications. Specifically, the goal of my departmental honors research is to investigate the effect of nanointerfaces on the semicrystalline structure of biopolymers through molecular dynamics (MD) simulations

Asian Parents' Perceptions of Child Disability and School Contact for Services

This study examined Asian parents' perceptions of children's disability and factors influencing their utilization of school services. Using the parent questionnaires from a large national sample of high school sophomores (the ELS:2002 data), survey results from Asian American (n=810) and European American parents (n=7710) were analyzed to examine cultural differences between the two ethnic groups as well as between immigrant vs. non-immigrant Asians. This study also assessed the extent to which parental characteristics (Belief About Learning, Recency of Immigration, English Proficiency, Socio-Economic Status, and whether they indicate their child is disabled) predict contacting the school for services. Results indicated that Asians were less likely than Europeans to believe that their child has a disability and also were less likely to contact the school for help. Nevertheless, immigrant parents sought help when they perceived that their child had a disability. Neither immigrant parent's length of stay in the U.S. nor English proficiency predicted the school contact behaviors. Implications for introducing school-based services and outreach for Asian American parents are suggested, particularly for recent immigrants

Is Private Long-Term Care Insurance Affordable For Older Adults?

Nationwide there are fewer than 7 million long-term care (LTC) insurance policies in force. Why do so few Americans buy private long-term care (LTC) insurance? Several theories have been offered as possible explanations, including the availability of Medicaid, misperceptions that Medicare or other policies cover LTC, beliefs that one\u27s own risk of needing LTC services is small, or desires to simply rely on children and spouses for LTC. This study examines another possible explanation - that private LTC insurance is simply unaffordable for most older Americans, which may be why they don\u27t buy it. This study begins by investigating the meaning of affordability in the context of private LTC insurance. I propose several definitions for affordability, drawing on concepts recently developed to gauge the affordability of acute-care health insurance and housing. Then using nationally representative data from the ongoing Health and Retirement Study (HRS) and the Rand HRS data the study examines the incidence of unaffordability of LTC insurance premiums among Americans over age 50, given each of our alternative definitions for it. I consider definitions for affordability, first, based on simple normative standards, such as whether remaining household income after paying for LTC insurance is above some (arbitrarily-set) threshold, and ratio definition, such as whether the ratio of premiums to income is less than some target amount, and more behavioral definitions of affordability, such as whether other adults with similar economic, demographic, and family circumstances are seen to purchase LTC insurance. In each case, the affordability definitions take into account the steep positive relationship between LTC insurance premiums and age-at-time-of-purchase. This analysis offers researchers and policymakers an operational framework for defining affordability, and for evaluating its relative importance as an explanation for non-purchase

Parental Perceived Need for Counseling for Adolescents’ Anxiety and Depression Symptoms: A Cross-Sectional Study

Objective This study examined the association between parental perceived need for counseling or mental health care services and adolescents’ subgroups of anxiety and depression symptoms (Anxiety-only, Depression-only, Anxiety-Depression, and None). Method Adolescent sample (N = 20,486, M = 14.69  years old, SD = 1.69) was drawn from the National Survey of Children’s Health 2017–2018 (NSCH 2017–2018). A chi-square test was used to analyze the association between two categorical variables. Results The Chi-square test was statistically significant, Χ2(6) = 7,914.33, p \u3c .01, V = .44. Adolescents from the Anxiety-Depression group received counseling or mental health care the most (80.94%), while 69.03% of those in the depression-only group and 44.86% in the Anxiety-only group received mental health services. Conclusions Caregivers of adolescents with Anxiety-only tended to perceive the least need for counseling or mental health care, compared with those with depression or both, suggesting the need to enhance mental health awareness

Independent and cumulative impacts of adverse childhood experiences on adolescent subgroups of anxiety and depression

The purpose of this study is to investigate the independent and cumulative impacts of Adverse Childhood Experiences (ACEs) on the subgroups of anxiety and depression among 12–17 aged adolescents in the U.S. A sample of 21,496 cases was derived from the 2017–2018 National Survey of Children’s Health (NSCH). Four adolescent subgroups were identified depending on their mental health condition: Anxiety-only (7.2%), Depression-only (1.5%), Anxiety-Depression (6.3%), and None (85.0%). All sociodemographic characteristics such as sex, age, race/ethnicity, and family structure had significant associations with the subgroups. Two multinomial logistic regression analyses were conducted to examine the independent and cumulative effects of ACEs on the subgroups. The findings suggested having a family member with severe mental illness showed the strongest relationship with the development of anxiety, depression, and both. A dose–response relationship was found between cumulative ACEs and the subgroups, with Anxiety-Depression as the most prevalent group when adolescents had multiple ACEs. Implications for service providers and future research are discussed

The role of memory processes and quality of lexical representations in native and non-native reading comprehension

This dissertation investigated what memory mechanisms support parsing and how they constrain sentence comprehension during first-language (L1) and second-language (L2) sentence reading. Although two memory-based accounts in sentence processing research, the capacity-based model (Just & Carpenter, 1992; King & Just, 1991) and the cue-based retrieval model (McElree & Vasishth, 2005; McElree, Vasishth, & Van Dyke, 2006; Nicenboim & Vasishth, 2018), demonstrated memory mechanisms supporting sentence comprehension, how readers access linguistic representations outside focal attention during reading is a largely unresolved issue, especially in L2 processing. Thus, the current research compared the predictions of the cue-based retrieval model and the capacity-based model in sentence comprehension using eye-tracking. Based on previous evidence for the cue-based retrieval model, this dissertation also examined whether enhancing the quality of lexical representations through semantic elaboration influences retrieval efficiency, given the assumption that providing additional semantic information for the target and/or the distractor increases the uniqueness of the target representation in memory by reducing similarity-based retrieval interference. Importantly, in order to understand whether the ability to use an efficient, cue-driven operation determines skilled versus less-skilled reading, L1 and L2 speakers’ reading patterns were compared. The findings that both L1 and L2 readers were sensitive to similarity-based retrieval interference during sentence comprehension suggest that sentence processing relies on a series of cue-based retrievals, but the ability to employ this operation itself may not distinguish skilled reading from less-skilled reading. In particular, the observed L1-L2 differences in reading patterns suggest that the most likely predictor of reading ability may be individuals’ quality of lexical representation

Recurrence of Ganglion Cysts Following Re-excision

Previous studies have examined the recurrence of ganglion cysts after surgical excision at a rate of 4 to 40%. However, recurrence after revision surgical excision is unknown. The purpose of this study was to define the incidence of recurrent ganglion cysts in patients who underwent a 2nd excisional procedure.https://jdc.jefferson.edu/cwicposters/1032/thumbnail.jp

Targeting Checkpoint Receptors and Molecules for Therapeutic Modulation of Natural Killer Cells

Among the most promising therapeutic modalities for cancer treatment is the blockade of immune checkpoint pathways, which are frequently co-opted by tumors as a major mechanism of immune escape. CTLA-4 and PD-1 are the representative examples, and their blockade by therapeutic antibodies leads to enhanced anti-tumor immunity with durable clinical responses, but only in a minority of patients. This has highlighted the need to identify and target additional immune checkpoints that can be exploited to further enhance immune responses to refractory cancers. These emerging targets include natural killer (NK) cell-directed checkpoint receptors (KIR and CD94/NKG2A) as well as the NK- and T cell-expressed checkpoints TIM-3, TIGIT, CD96, and LAG-3. Interestingly, the potentiation of anti-tumor immunity by checkpoint blockade relies not only on T cells but also on other components of the innate immune system, including NK cells. NK cells are innate lymphoid cells that efficiently kill tumor cells without MHC specificity, which is complementary to the MHC-restricted tumor lysis mediated by cytotoxic T cells. However, the role of these immune checkpoints in modulating the function of NK cells remains unclear and somewhat controversial. Unraveling the mechanisms by which these immune checkpoints function in NK cells and other immune cells will pave the way to developing new therapeutic strategies to optimize anti-tumor immunity while limiting cancer immune escape. Here, we focus on recent findings regarding the roles of immune checkpoints in regulating NK cell function and their potential application in cancer immunotherapy