Carotid plaque surface echogenicity predicts cerebrovascular events: An Echographic Multicentric Swiss Study.

BACKGROUND AND PURPOSE To determine the prognostic value for ischemic stroke or transitory ischemic attack (TIA) of plaque surface echogenicity alone or combined to degree of stenosis in a Swiss multicenter cohort METHODS: Patients with ≥60% asymptomatic or ≥50% symptomatic carotid stenosis were included. Grey-scale based colour mapping was obtained of the whole plaque and of its surface defined as the regions between the lumen and respectively 0-0.5, 0-1, 0-1.5, and 0-2 mm of the outer border of the plaque. Red, yellow and green colour represented low, intermediate or high echogenicity. Proportion of red color on surface (PRCS) reflecting low echogenictiy was considered alone or combined to degree of stenosis (Risk index, RI). RESULTS We included 205 asymptomatic and 54 symptomatic patients. During follow-up (median/mean 24/27.7 months) 27 patients experienced stroke or TIA. In the asymptomatic group, RI ≥0.25 and PRCS ≥79% predicted stroke or TIA with a hazard ratio (HR) of respectively 8.7 p = 0.0001 and 10.2 p < 0.0001. In the symptomatic group RI ≥0.25 and PRCS ≥81% predicted stroke or TIA occurrence with a HR of respectively 6.1 p = 0.006 and 8.9 p = 0.001. The best surface parameter was located at 0-0.5mm. Among variables including age, sex, degree of stenosis, stenosis progression, RI, PRCS, grey median scale values and clinical baseline status, only PRCS independently prognosticated stroke (p = 0.005). CONCLUSION In this pilot study including patients with at least moderate degree of carotid stenosis, PRCS (0-0.5mm) alone or combined to degree of stenosis strongly predicted occurrence of subsequent cerebrovascular events

Silver nanoparticles in sewage sludge: Bioavailability of sulfidized silver to the terrestrial isopod Porcellio scaber

Silver nanoparticles (AgNPs) are efficiently converted during the wastewater‐treatment process into sparingly soluble Ag sulfides (Ag2S). In several countries, sewage sludge is used as a fertilizer in agriculture. The bioavailability of sulfidized Ag to the terrestrial isopod Porcellio scaber was investigated. Sewage sludge containing transformed AgNPs was obtained from a laboratory‐scale sewage‐treatment plant operated according to Organisation for Economic Co‐operation and Development (OECD) guideline 303a. The results of transmission electron microscopy with energy dispersive X‐ray of sludge samples suggest that AgNPs were completely transformed to Ag2S. Adult isopods were exposed to OECD 207 soil substrate amended with the AgNP spiked sludge for 14 d (uptake phase) followed by an elimination phase in unspiked soil of equal duration. Most of the Ag measured in P. scaber at the end of the uptake phase was found in the hindgut (71%), indicating that only a minor part of the estimated Ag content was actually assimilated by the isopods with 16.3 and 12.7% found in the carcass and hepatopancreas, respectively. As a result of this, the Ag content of the animals dropped following transition to unspiked sludge within 2 d to one‐third of the previously measured Ag concentration and remained stable at this level until the end of the elimination period. The present study shows that Ag2S in sewage sludge is bioavailable to the terrestrial isopod P. scaber

Long-term effects of sulfidized silver nanoparticles in sewage sludge on soil microflora

The use of silver nanoparticles (AgNPs) in consumer products such as textiles leads to their discharge into wastewater and consequently to a transfer of the AgNPs to soil ecosystems via biosolids used as fertilizer. In urban wastewater systems (e.g., sewer, wastewater treatment plant [WWTP], anaerobic digesters) AgNPs are efficiently converted into sparingly soluble silver sulfides (Ag2S), mitigating the toxicity of the AgNPs. However, long-term studies on the bioavailability and effects of sulfidized AgNPs on soil microorganisms are lacking. Thus we investigated the bioavailability and long-term effects of AgNPs (spiked in a laboratory WWTP) on soil microorganisms. Before mixing the biosolids into soil, the sludges were either anaerobically digested or directly dewatered. The effects on the ammonium oxidation process were investigated over 140 d. Transmission electron microscopy (TEM) suggested an almost complete sulfidation of the AgNPs analyzed in all biosolid samples and in soil, with Ag2S predominantly detected in long-term incubation experiments. However, despite the sulfidation of the AgNPs, soil ammonium oxidation was significantly inhibited, and the degree of inhibition was independent of the sludge treatment. The results revealed that AgNPs sulfidized under environmentally relevant conditions were still bioavailable to soil microorganisms. Consequently, Ag2S may exhibit toxic effects over the long term rather than the short term

Cost-effective sol-gel synthesis of porous CuO nanoparticle aggregates with tunable specific surface area

CuO nanoparticles (NPs) are applied in various key technologies, such as catalysis, energy conversion, printable electronics and nanojoining. In this study, an economic, green and easy-scalable sol-gel synthesis method was adopted to produce submicron-sized nanoporous CuO NP aggregates with a specific surface area > 18 m²/g. To this end, a copper-carbonate containing precursor was precipitated from a mixed solution of copper acetate and ammonia carbonate and subsequently calcinated at T ≥ 250 °C. The thus obtained CuO nanopowder is composed of weakly-bounded agglomerates, which are constituted of aggregated CuO NPs with a tunable size in the range of 100–140 nm. The CuO aggregates, in turn, are composed of equi-axed primary crystallites with a tunable crystallite size in the range of 20–40 nm. The size and shape of the primary CuO crystallites, as well as the nanoporosity of their fused CuO aggregates, can be tuned by controlled variation of the degree of supersaturation of the solution via the pH and the carbonate concentration. The synthesized submicron-sized CuO aggregates can be more easily and safely processed in the form of a solution, dispersion or paste than individual NPs, while still offering the same enhanced reactivity due to their nanoporous architecture.ISSN:2045-232

Evaluation of a TEM based Approach for Size Measurement of Particulate (Nano)materials

An approach for the size measurement of particulate (nano)materials by transmission electron microscopy was evaluated. The approach combines standard operating procedures for specimen preparation, imaging, and image analysis, and it was evaluated on a series of certified reference materials and representative test materials with varying physical properties, including particle size, shape, and agglomeration state. The measurement of the median value of the minimal external particle diameter distribution was intra-laboratory validated. The validation study included an assessment of the limit of detection, working range, selectivity, precision, trueness, robustness, and ruggedness. An uncertainty that was associated to intermediate precision in the range of 1–7% and an expanded measurement uncertainty in the range of 7–20% were obtained, depending on the material and image analysis mode. No bias was observed when assessing the trueness of the approach on the certified reference materials ERM-FD100 and ERM-FD304. The image analysis method was validated in an inter-laboratory study by 19 laboratories, which resulted in a within-laboratory precision in the range of 2–8% and a between-laboratory precision of between 2% and 14%. The automation and standardization of the proposed approach significantly improves labour and cost eciency for the accurate and precise size measurement of the particulate materials. The approach is shown to be implementable in many other electron microscopy laboratories.JRC.F.6-Reference Material

Can forest trees take up and transport nanoplastics?

Plastic contamination of ecosystems has increased dramatically over the last decades, raising concerns about the negative impacts of plastic particles on aquatic and terrestrial systems. In recent years, the focus of most research has shifted from large fragments (macroplastic) to micro- (<5 mm) and more recently to nano-plastic (<1000 nm) particles as more evidence has come to light about their ubiquity in water, soils, and living systems, and their effects on ecosystem and human health. In this study, we investigate nanoplastic uptake in the roots of seedlings (1-2 years old) of three different tree species and assess their transport to different tissues. Parts of the main roots of silver birch (Betula pendula Roth), sessile oak (Quercus petraea Matt. [Liebl.]), and Norway spruce (Picea abies [L.] Karst.) were immersed for one or four days in a suspension containing 13C-labelled nano-sized polystyrene particles (13C-nPS; 99% 13C, d = 28 ± 8 (1 σ) nm). Carbon stable isotope analysis showed significant 13C enrichment (P < 0.05) in the immersed part of the root after one day of treatment in all three species, and after four days in Q. petraea alone. Signals of significant 13C enrichment were also found in the aboveground tissues of the trees. The stem of B. pendula in particular showed a significant 13C enrichment after one day of treatment (P < 0.01). This indicates that nanoplastic particles can be taken up through tree roots into the tree’s central cylinder, where they are subsequently conveyed through the tree by acropetal transport via the xylem.ISSN:1971-745

Scientific Basis for Regulatory Decision-Making of Nanomaterials; Report on the Workshop, 20-21 January 2014; Center of Applied Ecotoxicology, Dübendorf

The key findings of a workshop jointly organized by the Swiss Centre of Applied Ecotoxicity, the Swiss Centre for Applied Human Toxicology (SCANT), and the Federal Office of Public Health (FOPH) are summarized and provide a critical analysis of the current regulatory framework for nanomaterials and a snapshot of some hot topics in nanoscience

Volatile composition, emission pattern, and localization of floral scent emission in Mirabilis jalapa (Nyctaginaceae)

We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, β-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-β-ocimene was the major fragrance component. Fragrance release occurred in a time-dependent manner. The emission of volatiles, including (E)-β-ocimene, showed an evening-specific maximum (1700-2000 pm). The emission of (Z)-3-hexenyl acetate reached its maximum 3 h later. Histological (neutral red staining) and morphological studies (electron and light microscopy) of the flower surface and tissues of M. jalapa revealed differences in surface structures and tissue characteristics. The flower could be divided into four main sections, including the tube, the transition zone between tube and limb, a star-shaped center of the limb, and petaloid lobes of the limb. These petaloid lobes are the site of (E)-β-ocimene release. Stomata and trichomes found on the abaxial flower surface were not directly involved in fragrance release. Clear indications of osmophores involved in scent release could not be found. Thus, the results indicate that floral volatiles probably are released by diffuse emission in M. jalapa