263134 research outputs found
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Short- and medium-run impacts of preschool education: evidence from state pre-K programs
No full textThis paper studies the effects of state preschool programs on grade progression, child development, and health outcomes from ages 5 to 15 in the United States. Leveraging variation in the timing of pre-K program implementation across states and using data from state legislatures and two national surveys, I estimate the dynamic reduced-form impacts of a large group of pre-K programs. The findings show that pre-K significantly reduces grade retention, particularly for children from low socioeconomic backgrounds, with no significant differences between targeted and universal pre-K programs. There is suggestive evidence of short-run improvements in developmental and behavioral outcomes, alongside a temporary increase in illness-related missed school days, but no significant effects on overall health. These results highlight the lasting academic benefits of early childhood education, especially for disadvantaged children.sponsorship: Funding support from Research Foundation Flanders (FWO) grant number G0B8122N and the Washington Center for Equitable Growth is gratefully acknowledged. The findings and conclusions expressed are solely those of the author and do not represent the views of NCHS, FWO, or Equitable Growth. The author is grateful to Jessamyn Schaller, Tiemen Woutersen, Gary Solon, Ron Oaxaca, and Price Fishback for their advice and guidance, and to Patricia Barnes for her assistance in facilitating access to restricted-use data through the NCHS Research Data Center. (Washington Center for Equitable Growth|G0B8122N, Research Foundation Flanders (FWO), Price Fishback)status: Publishe
Mn onzuiverheden en bindingsdefecten in met ultralage energie geïmplanteerd grafeen
No full textThe functionalization of graphene with magnetic impurities and other defects opens new opportunities for fundamental research in low-dimensional systems and potential applications in spintronics, catalysis, and quantum materials.
This thesis investigates the controlled introduction of magnetic impurities into monolayer graphene via substitutional doping with manganese (Mn), as well as the creation of bond defects, using ultra-low energy (ULE) ion
implantation. The work addresses the defect formation mechanisms, structural stability, electronic properties and magnetic behavior using a wide range of characterization techniques.
The first part of the research focuses on achieving high substitutional incorporation of Mn into the graphene lattice. Optimizing ion implantation parameters, particularly increasing the ion energy from 40 eV to 60 eV, results
in a tenfold improvement in substitutional efficiency compared to earlier reports. The work also addresses the critical challenge of transferring the doped graphene layer to different substrates for further characterization or device integration. The final component of the thesis deals with bond defects which are created by ULE ion implantation, using noble gas ions (He, Ne, Ar) as model. These defects, which form at energies as low as 15 eV, are shown to create localized strain, which alters nearby electronic states and leads to charge trapping, significantly shifting the Fermi level
In summary, this thesis provides key insights into the mechanisms of substitutional doping and defect formation in the ultralow energy ion implantation regime, thereby establishing a foundation for future exploration of correlated electronic states in functionalized graphene.status: Publishe
Life-supporting care for persons with a Severe Persistent Mental Illness (SPMI): An explorative study regarding values and the search for meaning
No full textThis exploratory research aims to contribute to life-supporting care for people with a severe persistent mental illness (SPMI) in the context of socialization of care on the one hand and the possibility of active termination of life on request in a non-terminal situation on the other. More specifically, the importance of values and the search for are discussed. The first part of the research is a study of the international literature concerning this care in the given context. The second part is a qualitative study based on in-depth interviews with the main partners in this care, in particular the care recipients, their close relatives, the care providers and the policymakers. Finally, recommendations are formulated on the basis of the insights from the literature and qualitative research.status: Publishe
Robuuste Topologie Optimalisatie van Composietstructuren
No full textThis research explores the density-based topology optimization problem for composite structures at two structural scales: the microscale and macroscale.
At the microscale level, a novel approach to homogenization-based topology optimization for composite structures is introduced. Unlike the traditional approach—where the optimal microstructural configuration of the macrostructure is determined by optimizing the topology of each finite element discretizing the unit cell—the proposed approach optimizes the microstructural configuration from a prescribed library of feasible configurations designated by the designer. This alternative framing of the conventional homogenization-based topology optimization problem grants the designer complete control over the available microstructural configurations within the optimization process, ensuring that the microstructural configuration obtained at the end of the optimization process is manufacturable and compliant with the fabrication requirements.
At the macroscale level, a comprehensive framework for the topology optimization of fiber-reinforced composite structures is introduced, accounting for the material property variability that inevitably arises during their manufacturing process. By incorporating the material variability into the traditional topology optimization process, the resulting optimal topology is ensured to be robust—meaning that, in the presence of material property variations, it will perform reliably and in a predictable manner.status: Publishe
Bepaling van de permeabiliteit en de compactering van de textielversterking voor composiet injectieprocessen - naar een verbeterde productie van vezelversterkte polymeercomposieten
No full textAccurate permeability and fabric compaction measurements are essential for optimizing Liquid Composite Molding (LCM) processes used in the production of high-performance fiber-reinforced polymer composites. Techniques such as RTM, VARTM, and VARI enable the manufacturing of complex composite parts, but improvements in process characterization remain crucial for cost reduction and quality assurance. Recent international benchmarks (2011-2022) have advanced the standardization of permeability and compressibility testing. These efforts emphasized the need to control experimental variables—such as thickness measurement methods, cavity uniformity, compaction surface alignment, flow front tracking, and fluid viscosity-temperature relationships—to minimize variability and ensure comparability across different rigs. A radial permeability rig (RPR) was developed in accordance with current measurement protocols. Despite compliance with most requirements, deviation in the measured permeability were observed. For that reason, the influence of compliance correction on thickness measurements was investigated. Compression-induced changes in fabric stiffness and rig compliance were shown to significantly affect both direct and indirect measurement accuracy. Periodic calibration using laser sensors and universal testing machines proved essential for maintaining reliability. Based on these findings, key recommendations were formulated—such as the use of self-aligning plates, improved compliance correction strategies, and careful sensor integration—to support more consistent and accurate fabric compaction assessments across different permeability and compressibility experimental setups.status: Publishe
The impact of triethyl citrate leaching from HPMC-phthalate based isolated films on film permeability and thermal properties
No full textThe primary objective of this study was to investigate to what extent triethyl citrate (TEC), a commonly used plasticizer, was leached from hydroxypropyl methylcellulose phthalate (HPMC-P)-based isolated films and how this affects the permeability of the film for the model drug acetaminophen. The effect of the plasticizer on the glass transition temperature (Tg) of HPMC-P films was studied using modulated differential scanning calorimetry (mDSC) and utilized to estimate the extent of plasticizer leaching. A linear relationship between the Tg of the film and the weight proportion of the plasticizer was established and applied to develop a calibration curve, which enabled the quantification of plasticizer leaching from the isolated films. The leaching profiles of the plasticizer obtained from mDSC analysis demonstrated a slow migration from the film, 10 % w/w TEC films took nearly 24 h to completely leach out the plasticizer (95.1 ± 10.6 %) from the film, whereas 20 % w/w TEC films had leached out 76.7 ± 12.64 % of plasticizer within the similar exposure time. A concentration-dependent, slow leaching of plasticizer was observed, where films with a higher plasticizer content exhibited a reduced rate of leaching. This finding was consistent with the observed percentage of mass loss and the medium uptake capacity study of the films. Moreover, the addition of plasticizer at a concentration of 10 % w/w provided a permeability coefficient of 1.35 ± 0.19 e-06 (cm/s), while 20 % w/w yielded a coefficient of 1.97 ± 0.40 e-06 (cm/s), which directly contributed to an increase in the film's permeability compared to the films without plasticizer (1.19 ± 0.11 e-06 cm/s).status: Accepte
Biofabrication of high aspect ratio, flexible, and bioconductive micropillar arrays of PEDOT:PSS composite for 3D printed bioelectronics
No full textThe next generation of three-dimensional (3D) micro-additive manufacturing (AM) bioelectronics requires inks that simultaneously combine high electrical conductivity, biocompatibility, electrochemical stability, and compatibility with 3D processing. However, most existing inks fail to meet all these criteria, with processability and repeatability remaining major bottlenecks. This challenge is particularly serious in printed electronics technologies, such as Aerosol Jet® Printing (AJ®P), for which commercially available formulations tailored to specific applications are still scarce. Here, we present a novel poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)-based ink incorporating polyethylene glycol, ethylene glycol, and carboxymethyl cellulose to obtain a composite that fulfils all requirements, being conductive, processible by AJ®P and biocompatible. The formulation exhibits high conductivity (σ= 495.29 S · cm-1), electrochemical stability, and biocompatibility with both human fibroblasts and iPSC-derived neural stem cells. Its low viscosity (μ= 7.93 mPa · s) enables precise and repeatable AJ®P fabrication while supporting controlled, high-resolution 2D patterning and 3D microfabrication with aspect ratios up to 9. Dense or hollow microarrays of 24 flexible pillars (diameter ⩾ 35μm; elastic modulus = 3.1 × 106Pa per pillar) can be fabricated within 10 min, without masks or supporting materials. This work focuses on the material and process optimisation study of a customisable bioink for AJ®P in 3D micro-AM bioelectronics, with potential applications in 3D microelectrode arrays, biosensors, tissue engineering.sponsorship: Research Foundation Flanders (FWO) is acknowledged for financial support to Miriam Seiti (PhD fellowship N. 1SB1122N). The authors would like to thank Professor Elisabetta Ceretti and Professor Paola Serena Ginestra (TecMec Group, University of Brescia, IT) for their general supervision of the research project. (Fonds Wetenschappelijk Onderzoek|1SB1122N, MICS (Made in Italy - Circular and Sustainable)|Extended Partnership (Next Generation EU Italian))status: Accepte
Bank specialization and corporate innovation
No full textsponsorship: Huylebroek gratefully acknowledges financial support from Research Foundation Flanders (FWO) Grant 11C7923N. (Research Foundation Flanders (FWO)|11C7923N)status: Published onlin
Corporate implementation of certification and its impact on cocoa producers in Indonesia
No full textsponsorship: Fonds Wetenschappelijk Onderzoek|11J6123Nstatus: Published onlin
Navigating the pitfalls of outsourcing: Policy consulting in settings with lower administrative capacity
No full textsponsorship: Fonds Wetenschappelijk Onderzoek|11J4121Nstatus: Published onlin