Doctor of Philosophy

dissertationThis dissertation is comprised of three empirical studies that provide a complementary understanding regarding parental dissatisfaction, offspring's filial discrepancy, and their effects on parental health and wellbeing in late life. Data were collected in 2014 from a sample of 432 community-dwelling respondents (not couples) aged 60 to 79 in Linxi County of northern China with a total number of 1,223 offspring. The first study investigates whether parental dissatisfaction is linked to four health and wellbeing outcomes and explores potential psychological mechanisms that may underlie this proposed linkage. Findings indicate that parental dissatisfaction is significantly associated with the four outcomes, net of sociodemographic covariates. Findings also demonstrate that self-esteem and feeling useless mediate this association separately and simultaneously; suggesting both may function as individual and parallel psychological pathways underlying this linkage. The second study identifies the correlates of parental dissatisfaction in old age by testing five blocks of potential correlates. Financial strain, poor health, dissatisfaction with any child's marital status, and having more child-raising problems than other parents are associated with parental dissatisfaction. Parentally dissatisfied parents also reported failing to get along with at least one child, having at least one child with filial discrepancy, and believing in weaker filial obligation from offspring. The third one is a mixed-methods study using both quantitative and qualitative data. It examines the association between offspring's filial discrepancy and parental depression and explores the personal meaning of filial piety from the perspective of the older generation. Results from logistic regression indicate that filial discrepancy is significantly associated with parental depression, net of age, gender, financial strain, social support, and health status. Qualitative findings reveal that traditional filial piety values are fading even in one of the least developed Chinese counties, identifying six broad themes that reflect the coexistence of traditional and modern filial values regarding participants' definition of a filial child. These themes represent traditional filial piety values in a much-diluted form, filial piety values that converge with filial obligations in Western culture, and traditional filial piety beliefs in the absolute form, highlighting the complexity and evolution of the concept of filial piety

Modeling a decision support system for buildable designs

Ph.DDOCTOR OF PHILOSOPH

Glass transition temperature of particles for drug delivery

Drug delivery plays an important role in targeted therapies and nanoparticles which can be used as drug carriers and it’s a frequently researched topic. Poly(lactic-co-glycolic acid) (PLGA), a highly biocompatible polymer, has been used as a drug delivery vehicle in many studies. One of the challenges facing drug delivery particles is the problem of burst release which is when a large amount of the drug is suddenly released from the particle once it is placed in the body. This is generally undesirable as usually a slow and controlled release is preferred. The glass transition temperature has an effect on drug release behavior like the burst effect. In the case of PLGA, the effect can be pronounced since the glass transition temperature is close to body temperature. The glass transition phenomena of PLGA has been well researched in the past but the effect of thermal history on glass transition temperature of PLGA is yet to be investigated. With the development of temperature modulated differential scanning calorimetry (DSC), however, the glass transition temperature can be well separated from the effects of polymer aging commonly seen overlapping the glass transition in the DSC scan on initial heating of polymer samples. Thus, temperature modulated DSC provides the possibility to study the effect of thermal history on glass transition temperature. To accurately study the effects of thermal history on the glass transition temperature of PLGA particles, particles need to be made of the same size, using the same PLGA, by different methods. In this study, nanoprecipitation, nanoemulsion and electrospray jetting techniques are used to produce the PLGA nanoparticles. The size is optimized for all three methods to provide the stable production of nanoparticles with similar size distributions. The size optimization includes determination of factors such as the optimal surfactant concentration, optimal polymer concentration, and optimal sonication time. Several sets of nanoparticles made from nanoprecipitation and nanoemulsion are tested using temperature modulated differential scanning calorimetry (TMDSC). Results show that a clear glass transition temperature can be measured on the first heating scan. From these preliminary samples, it appears as though nanoemulsion particles would be preferable over nanoprecipitation particles for drug delivery because for nanoemulsion samples the glass transition temperature is higher and closer to the bulk value and the transition happens over a smaller temperature range. This suggests that particles made by nanoemulsion would have less burst release than particles made by nanoprecipitation

Meta‐analysis of the association between sodium‐glucose co‐transporter‐2 inhibitors and risk of skin cancer among patients with type 2 diabetes

A slight increase in melanoma risk was observed among sodium‐glucose co‐transporter‐2 (SGLT‐2) inhibitor users in the regular reports. However, the association remains uncertain. To address this issue, we performed a systematic search of electronic databases up to May 2, 2018 and a meta‐analysis of 21 randomized controlled trials (RCTs) involving 20 308 patients. We did not find a significant increase in risk of melanoma among SGLT‐2 inhibitor users (Peto odds ratio [OR], 2.17; 95% confidence interval [CI], 0.80‐5.89; I2, 0%). Similar results were observed in the subgroup analyses according to the type of SGLT‐2 inhibitor, type of control, ages of patients, race/ethnicity, and trial durations. For non‐melanoma skin cancer risk, no significant difference was observed when all trials were combined (Peto OR, 0.70; 95% CI, 0.47‐1.07; I2, 0%), while a significantly decreased risk was observed among trials with duration <52 weeks (Peto OR, 0.12; 95% CI, 0.02‐0.59; I2, 0%). No evidence of publication bias was detected in the analyses. Current evidence from RCTs did not support a significantly increased risk of skin cancer associated with SGLT‐2 inhibitors