This thesis focuses on the relationship between ethnic composition and both schooling outcomes and classroom behaviour, making the crucial distinction between the share of migrant-origin students and ethnic diversity. Ethnic school composition is seen as one of the explanations for the inequality of school performance between native- and migrant-origin students in Western societies. Although the use of the concept migrant origin is contested concept, the relationship between ethnic school composition and school performance is of interest to policymakers and social scientists in both the United States and Europe.
Although there is some evidence that total dietary antioxidant capacity (TDAC) is inversely associated with the presence of obesity, no longitudinal studies have been performed investigating the effect of TDAC on comprehensive measures of body composition over time. In this study, we included 4595 middle-aged and elderly participants from the Rotterdam Study, a population-based cohort. We estimated TDAC among these individuals by calculating a ferric reducing ability of plasma (FRAP) score based on data from food-frequency questionnaires. Body composition was assessed by means of dual X-ray absorptiometry at baseline and every subsequent 3-5 years. From these data, we calculated fat mass index (FMI), fat-free mass index (FFMI), android-to-gynoid fat ratio (AGR), body fat percentage (BF%) and body mass index (BMI). We also assessed hand grip strength at two time points and prevalence of sarcopenia at one time point in a subset of participants. Data were analyzed using linear mixed models or multinomial logistic regression models with multivariable adjustment. We found that higher FRAP score was associated with higher FFMI (0.091 kg/m2 per standard deviation (SD) higher FRAP score, 95% CI 0.031; 0.150), lower AGR (-0.028, 95% CI -0.053; -0.003), higher BMI (0.115, 95% CI 0.020; 0.209) and lower BF% (-0.223, 95% CI -0.383; -0.064) across follow-up after multivariable adjustment. FRAP score was not associated with hand grip strength or sarcopenia. Additional adjustment for adherence to dietary guidelines and exclusion of individuals with comorbid disease at baseline did not change our results. In conclusion, dietary intake of antioxidants may positively affect the amount of lean mass and overall body composition among the middle-aged and elderly.
Collaborative learning tasks may represent an effective way to stimulate higher-order processes among high-ability students in regular classrooms. This study investigatedthe effects of task structure and group composition on the elaboration and metacognitive activities of 11th grade preuniversity students during a collaborative learning task: 102 students worked in small groups. On an ill-structured or moderately structured task. Differential effects forcognitive ability were investigated using a continuous measure. Likewise, the effects of group composition were examined using a continuous measure of the cognitiveheterogeneity of the group. The group dialogues were transcribed and coded. Analysis revealed an interaction effect between task structure and cognitive abilityon students’ elaboration and metacognitive activities. Task structure had a negative effect on the elaborative contributions of high-ability students. For students with lower abilities, task structure had a positive effect onelaboration and metacognitive activities. No effects were found of the cognitive heterogeneity of the group. Group composition seemed not to be related to group interactionamong 11th grade pre-university students. The results indicate that open-ended collaborative tasks with little guidance and directions on how to handle them, canstimulate higher-order processes among high-ability students and may offer them the challenge they need.
MULTIFILE
Currently, many novel innovative materials and manufacturing methods are developed in order to help businesses for improving their performance, developing new products, and also implement more sustainability into their current processes. For this purpose, additive manufacturing (AM) technology has been very successful in the fabrication of complex shape products, that cannot be manufactured by conventional approaches, and also using novel high-performance materials with more sustainable aspects. The application of bioplastics and biopolymers is growing fast in the 3D printing industry. Since they are good alternatives to petrochemical products that have negative impacts on environments, therefore, many research studies have been exploring and developing new biopolymers and 3D printing techniques for the fabrication of fully biobased products. In particular, 3D printing of smart biopolymers has attracted much attention due to the specific functionalities of the fabricated products. They have a unique ability to recover their original shape from a significant plastic deformation when a particular stimulus, like temperature, is applied. Therefore, the application of smart biopolymers in the 3D printing process gives an additional dimension (time) to this technology, called four-dimensional (4D) printing, and it highlights the promise for further development of 4D printing in the design and fabrication of smart structures and products. This performance in combination with specific complex designs, such as sandwich structures, allows the production of for example impact-resistant, stress-absorber panels, lightweight products for sporting goods, automotive, or many other applications. In this study, an experimental approach will be applied to fabricate a suitable biopolymer with a shape memory behavior and also investigate the impact of design and operational parameters on the functionality of 4D printed sandwich structures, especially, stress absorption rate and shape recovery behavior.
Chemical preservation is an important process that prevents foods, personal care products, woods and household products, such as paints and coatings, from undesirable change or decomposition by microbial growth. To date, many different chemical preservatives are commercially available, but they are also associated with health threats and severe negative environmental impact. The demand for novel, safe, and green chemical preservatives is growing, and this process is further accelerated by the European Green Deal. It is expected that by the year of 2050 (or even as soon as 2035), all preservatives that do not meet the ‘safe-by-design’ and ‘biodegradability’ criteria are banned from production and use. To meet these European goals, there is a large need for the development of green, circular, and bio-degradable antimicrobial compounds that can serve as alternatives for the currently available biocidals/ preservatives. Anthocyanins, derived from fruits and flowers, meet these sustainability goals. Furthermore, preliminary research at the Hanze University of Applied Science has confirmed the antimicrobial efficacy of rose and tulip anthocyanin extracts against an array of microbial species. Therefore, these molecules have the potential to serve as novel, sustainable chemical preservatives. In the current project we develop a strategy consisting of fractionation and state-of-the-art characterization methods of individual anthocyanins and subsequent in vitro screening to identify anthocyanin-molecules with potent antimicrobial efficacy for application in paints, coatings and other products. To our knowledge this is the first attempt that combines in-depth chemical characterization of individual anthocyanins in relation to their antimicrobial efficacy. Once developed, this strategy will allow us to single out anthocyanin molecules with antimicrobial properties and give us insight in structure-activity relations of individual anthocyanins. Our approach is the first step towards the development of anthocyanin molecules as novel, circular and biodegradable non-toxic plant-based preservatives.
Worldwide, coral reefs are rapidly declining due to increased sea water temperatures and other environmental stresses (Figure 1). To counter the extinction of major coral reef building species on the island of Bonaire, the non-profit organization Reef Renewal Foundation Bonaire is restoring degraded reef sites using corals that are grown in local nurseries. In these nurseries, corals are propagated on artificial trees using fragmentation. After 6-8 months of growth in the nursery, the corals are transplanted to degraded reef sites around the island. Over the years more than 21.000 corals have been outplanted to reef restoration sites in this way. These corals show high survivorship under natural reef conditions but remain under threat by environmental disturbances, such as increased water temperatures, diseases, and competition with macroalgae. A promising intervention to increase reef persistence and resilience is to manipulate the coral-associated microbiome. At present, the composition of the microbiome in nursery-reared and outplanted corals on Bonaire is unknown. The aim of the current project is to identify and isolate naturally occurring beneficial bacteria that may stimulate the resilience of these corals. Our key objectives are: 1) to assess the presence of functionally beneficial bacteria in corals in nursery and restoration sites on Bonaire using metagenomic screening. 2) to design culture strategies to isolate these functionally beneficial bacteria. In the future, a selection of these beneficial bacteria can be applied to the corals to increase their resilience against environmental disturbances.
