753 research outputs found

    Toward the systematic identification of microplastics in the environment: evaluation of a new independent software tool (siMPle) for spectroscopic analysis

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    Microplastics (MP) are ubiquitous within the environment, but the analysis of this contaminant is currently quite diverse, and a number of analytical methods are available. The comparability of results is hindered as even for a single analytical method such as Fourier transform infrared spectroscopy (FT-IR) the different instruments currently available do not allow a harmonized analysis. To overcome this limitation, a new free of charge software tool, allowing the systematic identification of MP in the environment (siMPle) was developed. This software tool allows a rapid and harmonized analysis of MP across FT-IR systems from different manufacturers (Bruker Hyperion 3000, Agilent Cary 620/670, PerkinElmer Spotlight 400, Thermo Fischer Scientific Nicolet iN10). Using the same database and the automated analysis pipeline (AAP) in siMPle, MP were identified in samples that were analyzed with instruments with different detector systems and optical resolutions, the results of which are discussed

    The fate of cerium oxide nanoparticles in sediments and their routes of uptake in a freshwater worm

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    The relative importance of ingestion and transdermal uptake of nanomaterials is poorly understood, particularly in sediment dwelling organisms, where diet has the potential to contribute significantly to particle accumulation. In aquatic sediments, nanoparticles may partition to bind with the solid fraction of sediment, be freely mobile in the pore water or, for certain metal/metal oxides, undergo dissolution, each of which could influence the route of nanoparticle uptake. Here, we used the freshwater worm Lumbriculus variegatus as a model species. We took advantage of its unique feeding and non-feeding life-stages to assess the contribution of dietary and transdermal uptake in the bioaccumulation of cerium oxide nanoparticles (CeO2 NP) and soluble Ce(III)NO3. Distribution of cerium between the solid, colloidal and soluble fractions in the sediments was determined through sediment separations using micro and ultrafiltration techniques. We assessed particles of differing sizes (10, 28 and 615 nm CeO2) and stabilizing surfactants (10 nm electrostatic Citrate-CeO2 and steric stabilized PEG-CeO2). Soluble Ce(III)NO3, was found to accumulate readily across the skin of the worms whilst nanoparticles were not. Sediments reduced the uptake of CeIII by limiting the presence of dissolved species of cerium in the pore waters. Neither particle size nor the coatings studied altered the distribution of nanoparticles between solid and colloidal fractions of the sediment, with ∼99% associated to the solid phase. Any uptake of CeO2 nanoparticles into worms was only through ingestion. Stabilized 10 nm particles were retained even after gut clearance, indicating that these particles may translocate across the gut wall

    Emotional Climate, Feeding Practices, and Feeding Styles: An Observational Analysis of the Dinner Meal in Head Start Families

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    BACKGROUND: A number of studies conducted with ethnically diverse, low-income samples have found that parents with indulgent feeding styles had children with a higher weight status. Indulgent parents are those who are responsive to their child\u27s emotional states but have problems setting appropriate boundaries with their child. Because the processes through which styles impact child weight are poorly understood, the aim of this study was to observe differences in the emotional climate created by parents (including affect, tone of voice, and gestures) and behavioral feeding practices among those reporting different feeding styles on the Caregiver\u27s Feeding Styles Questionnaire. A secondary aim was to examine differences on child weight status across the feeding styles. METHODS: Participants were 177 Head Start families from Houston, Texas (45% African-American; 55% Hispanic). Using an observational approach, the relationship between the observed emotional climate of the meal, behavioral feeding practices, and self-reported parent feeding styles were examined. Mean age of the children was 4.4 years (SD = 0.7) equally distributed across gender. Families were observed on 3 separate dinner occasions. Heights and weight were measured on the parents and children. RESULTS: Parents with self-reported indulgent feeding styles made fewer demands on their children to eat during dinner and showed lower levels of negative affect and intrusiveness. Surprisingly, these parents also showed higher levels of emotional detachment with their children during dinner. Hispanic boys with indulgent parents had significantly higher BMI z scores compared to Hispanic boys in the other three feeding style groups. No other differences were found on child weight status. CONCLUSIONS: Results suggest that the emotional climate created by indulgent parents during dinner and their lack of demands on their children to eat may play an important role in how young children become overweight. Numerous observed emotional climate and behavioral differences were found between the other self-reported feeding styles as well. Results suggest that parents\u27 self-reported feeding styles may be a proxy for the emotional climate of the dinner meal, which may in turn influence the child\u27s eating behaviors and weight status

    Similarity assessment of metallic nanoparticles within a risk assessment framework: a case study on metallic nanoparticles and lettuce

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    Similarity assessment is one of the means of optimally using scarcely available experimental data on the fate and hazards of nanoforms (NFs) for regulatory purposes. For a set of NFs that are shown to be similar it is allowed in a regulatory context to apply the information available on any of the NFs within the group to the whole set of NFs. Obviously, a proper justification for such a similarity assessment is to be provided. Within the context of exemplifying such a justification, a case study was performed aimed at assessing the similarity of a set of spherical metallic NFs that different with regard to chemical composition (three metals) and particle size (three different sizes). The endpoints of assessment were root elongation and biomass increase of lettuce (Lactuca sativa L.) seedlings and exposure assessment was performed in order to express the actual exposure concentration in terms of time-weighted average particle concentrations. The results of the study show that for the specific endpoints assessed, chemical composition is driving NF toxicity and this is mostly due to impacts on the fate of the NFs. On the other hand, particle size of Cu NFs had a negligible impact on the dose-response relationships for the specific endpoints assessed. It is thus concluded that hazard data available on spherical Cu NF tested in our case can be used to inform on the hazards of any spherical Cu NF within the size range of 25–100 nm, but only applies for the certain endpoints. Also, toxicity data for the Cu2+-ion are suited for such a similarity assessment

    Many-body physics of a quantum fluid of exciton-polaritons in a semiconductor microcavity

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    Some recent results concerning nonlinear optics in semiconductor microcavities are reviewed from the point of view of the many-body physics of an interacting photon gas. Analogies with systems of cold atoms at thermal equilibrium are drawn, and the peculiar behaviours due to the non-equilibrium regime pointed out. The richness of the predicted behaviours shows the potentialities of optical systems for the study of the physics of quantum fluids.Comment: Proceedings of QFS2006 conference to appear on JLT

    fMRI evidence of ‘mirror’ responses to geometric shapes

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    Mirror neurons may be a genetic adaptation for social interaction [1]. Alternatively, the associative hypothesis [2], [3] proposes that the development of mirror neurons is driven by sensorimotor learning, and that, given suitable experience, mirror neurons will respond to any stimulus. This hypothesis was tested using fMRI adaptation to index populations of cells with mirror properties. After sensorimotor training, where geometric shapes were paired with hand actions, BOLD response was measured while human participants experienced runs of events in which shape observation alternated with action execution or observation. Adaptation from shapes to action execution, and critically, observation, occurred in ventral premotor cortex (PMv) and inferior parietal lobule (IPL). Adaptation from shapes to execution indicates that neuronal populations responding to the shapes had motor properties, while adaptation to observation demonstrates that these populations had mirror properties. These results indicate that sensorimotor training induced populations of cells with mirror properties in PMv and IPL to respond to the observation of arbitrary shapes. They suggest that the mirror system has not been shaped by evolution to respond in a mirror fashion to biological actions; instead, its development is mediated by stimulus-general processes of learning within a system adapted for visuomotor control

    Co-occurrence of macroplastics, microplastics, and legacy and emerging plasticisers in UK soils

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    Despite a theoretical link between plastic and plasticiser occurrence in the terrestrial environment, there are few empirical studies of the relationship between these contaminants in soils. We carried out a field study to assess the cooccurrence of plastic waste, and legacy and emerging plasticisers in UK soils (n = 19) from various land uses (woodlands, urban roadsides, urban parklands, landfill-associated). Surface plastics and soil microplastics were quantified and characterised using ATR-FTIR and μ-FTIR. Eight legacy (phthalate) and three emerging (adipate, citrate, trimellitate) plasticisers were quantified using GC–MS. Surface plastics were found at higher prevalence at landfillassociated and urban roadside sites, with levels significantly (2 orders of magnitude) greater than in woodlands. Microplastics were detected in landfill-associated (mean 12.3 particles g−1 dw), urban roadside (17.3 particles g−1dw) and urban parkland (15.7 particles g−1 dw) soils, but not in woodland soils. The most commonly detected polymers were polyethene, polypropene and polystyrene. Mean ∑plasticiser concentration in urban roadside soils (3111 ng g−1 dw) was significantly higher than in woodlands (134 ng g−1 dw). No significant difference was found between landfill-associated (318 ng g−1 dw) and urban parkland (193 ng g−1 dw) soils and woodlands. Di-n-butyl phthalate (94.7% detection frequency) and the emerging plasticiser trioctyl trimellitate (89.5%) were the most commonly detected plasticisers, with diethylhexyl phthalate (493 ng g−1 dw) and di-iso-decyl phthalate (96.7 ng g−1 dw) present at the highest concentrations. ∑plasticiser concentrations were significantly correlated with surface plastic (R2 = 0.23), but not with soil microplastic concentrations. Whilst plastic litter seems a fundamental source of plasticisers in soils, mechanisms such as airborne transport from source areas may be as important. Based on the data from this study, phthalates remain the dominant plasticisers in soils, but emerging plasticisers are already widespread, as reflected by their presence in all land uses studied
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