Early impact of a new food store intervention on health-related outcomes

Neighbourhood food environments influence what people choose to eat and consequently affect their health. Literature suggests that having supermarkets/grocery stores with healthier food options in a neighbourhood supports intake of healthy food as opposed to having abundance of fast food and convenience stores. This thesis systematically reviewed published literature on new food store interventions on health-related outcomes (manuscript 1), and examined early health-related impact of a community-based food intervention in Saskatoon (manuscript 2). The systematic review addressed the question ‘How do new food store (supermarket/grocery store) interventions influence health-related outcomes in adults?’ The review followed the guidelines recommended by the Effective Public Health Practice Project (EPHPP) and identified 11 records representing 7 interventions. The methodological quality rating found that 6 studies were of ‘weak’ methodological quality, one was of ‘moderate’ and two studies had ‘strong’ methodological quality. Relevant outcomes reported by these studies were fruit and vegetable consumption, self-rated health, psychological health, BMI, perceptions of food access, and household food availability. Of these outcomes, perceptions of food access and psychological health showed significant improvement; however, other outcomes showed mixed results. A prospective longitudinal study was conducted to investigate the health-related impact of a new food store in a former food desert in Saskatoon. One hundred and fifty-six shoppers of the new food store were followed-up repeatedly and their health-related outcomes were assessed using a questionnaire. A generalized estimating equations approach was used for data analysis. Study participants were mainly female, Aboriginal, of low income, and had high school and some post-secondary education. They showed dose-response associations between the frequency of use of the new grocery store and the odds of reporting household food security, mental health, and BMI over time, and these associations were significantly modified by participants’ level of education, household income, and pre-existing chronic conditions, respectively. Further, having multiple disadvantaged conditions (Aboriginal ethnicity, seniors, low-income and low-education) significantly modified the effect of the new grocery store use on participants’ mental health. Although the systematic review suggested that previous studies yielded conflicting findings, this thesis research revealed convincing results. In contrast to the limited body of literature, this study found that when the shopping frequency is taken into account, the new grocery store did have a positive effect on mitigating household food security, mental health, and BMI. Further, socioeconomic status, multiple disadvantage, and previous chronic diseases moderate these effects. The results are valuable to advance the knowledge in food environment interventions research

A Numerical Thermo-Chemo-Flow Analysis of Thermoset Resin Impregnation in LCM Processes

This paper presents a numerical framework for modelling and simulating convection–diffusion–reaction flows in liquid composite moulding (LCM). The model is developed in ANSYS Fluent with customised user-defined-functions (UDFs), user-defined-scalar (UDS), and user-defined memory (UDM) codes to incorporate the cure kinetics and rheological characteristics of thermoset resin impregnation. The simulations were performed adopting volume-of-fluid (VOF)—a multiphase flow solution—based on finite volume method (FVM). The developed numerical approach solves Darcy’s law, heat transfer, and chemical reactions in LCM process simultaneously. Thereby, the solution scheme shows its ability to provide information on flow-front, viscosity development, degree of cure, and rate of reaction at once unlike existing literature that commonly focuses on impregnation stage and cure stage in isolation. Furthermore, it allows online monitoring, controlled boundary conditions, and injection techniques (for design of manufacturing) during the mould filling and curing stages. To examine the validity of the model, a comparative analysis was carried out for a simple geometry, in that the numerical results indicate good agreement—3.4% difference in the degree of cure compared with previous research findings

Infusion Simulation of Graphene-Enhanced Resin in LCM for Thermal and Chemo-Rheological Analysis

The present numerical study proposes a framework to determine the heat flow parameters—specific heat and thermal conductivity—of resin–graphene nanoplatelets (GNPs) (modified) as well as non-modified resin (with no GNPs). This is performed by evaluating the exothermic reaction which occurs during both the filling and post-filling stages of Liquid Composite Moulding (LCM). The proposed model uses ANSYS Fluent to solve the Stokes–Brinkman (momentum and mass), energy, and chemical species conservation equations to a describe nano-filled resin infusion, chemo-rheological changes, and heat release/transfer simultaneously on a Representative Volume Element (RVE). The transient Volume-of-Fluid (VOF) method is employed to track free-surface propagation (resin–air interface) throughout the computational domain. A User-Defined Function (UDF) is developed together with a User-Defined Scaler (UDS) to incorporate the heat generation (polymerisation), which is added as an extra source term into the energy equation. A separate UDF is used to capture intra-tow (microscopic) flow by adding a source term into the momentum equation. The numerical findings indicate that the incorporation of GNPs can accelerate the curing of the resin system due to the high thermal conductivity of the nanofiller. Furthermore, the model proves its capability in predicting the specific heat and thermal conductivity of the modified and non-modified resin systems utilising the computed heat of reaction data. The analysis shows an increase of ∼15% in the specific heat and thermal conductivity due to different mould temperatures applied (110–170 °C). This, furthermore, stresses the fact that the addition of GNPs (0.2 wt.%) improves the resin-specific heat by 3.68% and thermal conductivity by 58% in comparison to the non-modified thermoset resin. The numerical findings show a satisfactory agreement with and in the range of experimental data available in the literature