ORCID Profile
0000-0001-5894-8839
Current Organisations
Universiteit Leiden Faculteit der Wiskunde en Natuurwetenschappen
,
RIVM
,
National Neuroscience Institute
,
University of Nottingham
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Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9EN00448C
Abstract: The chemical composition and properties of environmental media determine nanomaterial (NM) transport, fate, biouptake, and organism response.
Publisher: Informa UK Limited
Date: 10-09-2015
DOI: 10.3109/17435390.2014.999139
Abstract: Silver nanoparticles (NPs) are used in more consumer products than any other nanomaterial and their release into the environment is unavoidable. Of primary concern is the wastewater stream in which most silver NPs are transformed to silver sulfide NPs (Ag2S-NPs) before being applied to agricultural soils within biosolids. While Ag2S-NPs are assumed to be biologically inert, nothing is known of their effects on terrestrial plants. The phytotoxicity of Ag and its accumulation was examined in short-term (24 h) and longer-term (2-week) solution culture experiments with cowpea (Vigna unguiculata L. Walp.) and wheat (Triticum aestivum L.) exposed to Ag2S-NPs (0-20 mg Ag L(-1)), metallic Ag-NPs (0-1.6 mg Ag L(-1)), or ionic Ag (AgNO3 0-0.086 mg Ag L(-1)). Although not inducing any effects during 24-h exposure, Ag2S-NPs reduced growth by up to 52% over a 2-week period. This toxicity did not result from their dissolution and release of toxic Ag(+) in the rooting medium, with soluble Ag concentrations remaining below 0.001 mg Ag L(-1). Rather, Ag accumulated as Ag2S in the root and shoot tissues when plants were exposed to Ag2S-NPs, consistent with their direct uptake. Importantly, this differed from the form of Ag present in tissues of plants exposed to AgNO3. For the first time, our findings have shown that Ag2S-NPs exert toxic effects through their direct accumulation in terrestrial plant tissues. These findings need to be considered to ensure high yield of food crops, and to avoid increasing Ag in the food chain.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 02-2013
Publisher: Informa UK Limited
Date: 11-01-2022
DOI: 10.1080/13561820.2021.2007864
Abstract: Interprofessional collaboration (IPC) is key to ensuring safe quality care for patients. However, IPC intervention outcomes are variable, leading to calls for systems theories to understand complex interactions in healthcare. Using networked ecological systems theory (NEST), we aimed to uncover facilitators and barriers impacting the interactions between nurses and physicians in a specialty healthcare center. A qualitative study involving 55 non-participant observations and 17 in idual semi-structured interviews was conducted at the National Neuroscience Institute of Singapore from April 2019 to March 2021. Template analysis was used to analyze the data. The most important IPC facilitators were exosystemic institutional support and physicians' willingness to engage in IPC in the microsystems that together enabled the establishment of disease-based outpatient programs fostering patient-centered interactions among different healthcare professionals (HCP). We also found that patient-, disease-, and systems-related knowledge played an important role in facilitating IPC. Macrosystemic entrenchments such as intraprofessional composition of ward rounds emerged as a significant barrier. However, microsystemic efforts such as chat groups connecting all HCP involved in the care of the patients in the wards have fostered IPC. Although still preliminary, these findings suggest NEST can be useful to inform systematic interventions to improve IPC.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5EN00207A
Abstract: A schematic summary of the most important transformation processes a NM may undergo during environmental transport, and the parameters of highest importance for inclusion in models of NM environmental fate and uptake.
Publisher: American Chemical Society (ACS)
Date: 18-08-2015
Abstract: The bioavailability of organic chemicals in soil and sediment is an important area of scientific investigation for environmental scientists, although this area of study remains only partially recognized by regulators and industries working in the environmental sector. Regulators have recently started to consider bioavailability within retrospective risk assessment frameworks for organic chemicals by doing so, realistic decision-making with regard to polluted environments can be achieved, rather than relying on the traditional approach of using total-extractable concentrations. However, implementation remains difficult because scientific developments on bioavailability are not always translated into ready-to-use approaches for regulators. Similarly, bioavailability remains largely unexplored within prospective regulatory frameworks that address the approval and regulation of organic chemicals. This article discusses bioavailability concepts and methods, as well as possible pathways for the implementation of bioavailability into risk assessment and regulation in addition, this article offers a simple, pragmatic and justifiable approach for use within retrospective and prospective risk assessment.
Publisher: Elsevier BV
Date: 02-2022
Publisher: MDPI AG
Date: 05-2023
Abstract: Despite decades of research on the impact of interprofessional collaboration (IPC), we still lack definitive proof that team-based care can lead to a tangible effect on healthcare outcomes. Without return on investment (ROI) evidence, healthcare leaders cannot justifiably throw their weight behind IPC, and the institutional push for healthcare manpower reforms crucial for facilitating IPC will remain variable and fragmentary. The lack of proof for the ROI of IPC is likely due to a lack of a unifying conceptual framework and the over-reliance on the single-method study design. To address the gaps, this paper describes a protocol which uses as a framework the Quadruple Aim which examines the ROI of IPC using four dimensions: patient outcomes, patient experience, provider well-being, and cost of care. A multimethod approach is proposed whereby patient outcomes are measured using quantitative methods, and patient experience and provider well-being are assessed using qualitative methods. Healthcare costs will be calculated using the time-driven activity-based costing methodology. The study is set in a Singapore-based national and regional center that takes care of patients with neurological issues.
Publisher: Oxford University Press (OUP)
Date: 20-10-2011
DOI: 10.1093/JXB/ERR254
Abstract: The focus of the present study was to investigate the mechanisms for the alleviation of Cu toxicity in plants by coexistent cations (e.g. Al(3+), Mn(2+), Ca(2+), Mg(2+), H(+), Na(+), and K(+)) and the development of an electrostatic model to predict 50% effect activities (EA50s) accurately. The alleviation of Cu(2+) toxicity was evaluated in several plants in terms of (i) the electrical potential at the outer surface of the plasma membrane (PM) (Ψ(0)(°)) and (ii) competition between cations for sites at the PM involved in the uptake or toxicity of Cu(2+), the latter of which is invoked by the Biotic Ligand Model (BLM) as the sole explanation for the alleviation of toxicity. The addition of coexistent cations into the bulk-phase medium reduces the negativity of Ψ(0)(°) and hence decreases the activity of Cu(2+) at the PM surface. Our analyses suggest that the alleviation of toxicity results primarily from electrostatic effects (i.e. changes in both the Cu(2+) activity at the PM surface and the electrical driving force across the PM), and that BLM-type competitive effects may be of lesser importance in plants. Although this does not exclude the possibility of competition, the data highlight the importance of electrostatic effects. An electrostatic model was developed to predict Cu(2+) toxicity thresholds (EA50s), and the quality of its predictive capacity suggests its potential utility in risk assessment of copper in natural waters and soils.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-11-2016
DOI: 10.1212/CPJ.0000000000000319
Abstract: There are limited data to guide clinicians in differentiating tumefactive multiple sclerosis (TMS) from CNS neoplasms. Identifying distinguishing features will inform diagnosis and management and avoid unnecessary diagnostic biopsy. Our study aimed to determine the clinical and radiologic features that differentiate TMS from glioma and CNS lymphoma (CNSL) in patients who present with tumefactive lesions. We retrospectively reviewed all patients with tumefactive lesions and histologically proven or clinically diagnosed TMS, glioma, or CNSL at our tertiary center from 1999 to 2012. Two independent blinded neuroradiologists rated MRI brain scans at presentation. We correlated patients' demographic, clinical, laboratory, and radiologic data to final diagnosis. A total of 133 patients (10 TMS, 85 glioma, 38 CNSL) were analyzed. Patients with TMS were younger and a greater proportion were women. Presenting symptoms did not distinguish between diagnoses. TMS lesions were smaller compared to glioma and CNSL, had no or mild mass effect, and were always associated with contrast enhancement. Radiologic features that were more frequent in TMS lesions were incomplete rim (open-ring) enhancement, incomplete peripheral diffusion restriction, and mixed T2 signal and CT hypoattenuation of MRI-enhancing components (all p 0.05). Radiologic features but not presenting symptoms are useful in distinguishing TMS from CNS neoplasms.
Publisher: Oxford University Press (OUP)
Date: 30-11-2010
Publisher: Wiley
Date: 27-01-2004
DOI: 10.1002/IEAM.1502
Location: Netherlands
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Kevin Tan.