Exposure of silver-nanoparticles and silver-ions to lung cells in vitro at the air-liquid interface

BACKGROUND: Due to its antibacterial properties, silver (Ag) has been used in more consumer products than any other nanomaterial so far. Despite the promising advantages posed by using Ag-nanoparticles (NPs), their interaction with mammalian systems is currently not fully understood. An exposure route via inhalation is of primary concern for humans in an occupational setting. Aim of this study was therefore to investigate the potential adverse effects of aerosolised Ag-NPs using a human epithelial airway barrier model composed of A549, monocyte derived macrophage and dendritic cells cultured in vitro at the air-liquid interface. Cell cultures were exposed to 20 nm citrate-coated Ag-NPs with a deposition of 30 and 278 ng/cm2 respectively and incubated for 4 h and 24 h. To elucidate whether any effects of Ag-NPs are due to ionic effects, Ag-Nitrate (AgNO3) solutions were aerosolised at the same molecular mass concentrations. RESULTS: Agglomerates of Ag-NPs were detected at 24 h post exposure in vesicular structures inside cells but the cellular integrity was not impaired upon Ag-NP exposures. Minimal cytotoxicity, by measuring the release of lactate dehydrogenase, could only be detected following a higher concentrated AgNO3-solution. A release of pro-inflammatory markers TNF-alpha and IL-8 was neither observed upon Ag-NP and AgNO3 exposures as well as was not affected when cells were pre-stimulated with lipopolysaccharide (LPS). Also, an induction of mRNA expression of TNF-alpha and IL-8, could only be observed for the highest AgNO3 concentration alone or even significantly increased when pre-stimulated with LPS after 4 h. However, this effect disappeared after 24 h. Furthermore, oxidative stress markers (HMOX-1, SOD-1) were expressed after 4 h in a concentration dependent manner following AgNO3 exposures only. CONCLUSIONS: With an experimental setup reflecting physiological exposure conditions in the human lung more realistic, the present study indicates that Ag-NPs do not cause adverse effects and cells were only sensitive to high Ag-ion concentrations. Chronic exposure scenarios however, are needed to reveal further insight into the fate of Ag-NPs after deposition and cell interactions.

Holocene climate, fire and vegetation dynamics at the treeline in the Northwestern Swiss Alps

Treelines are expected to rise to higher elevations with climate warming; the rate and extent however are still largely unknown. Here we present the first multi-proxy palaeoecological study from the treeline in the Northwestern Swiss Alps that covers the entire Holocene. We reconstructed climate, fire and vegetation dynamics at Iffigsee, an alpine lake at 2,065 m a.s.l., by using seismic sedimentary surveys, loss on ignition, visible spectrum reflectance spectroscopy, pollen, spore, macrofossil and charcoal analyses. Afforestation with Larix decidua and tree Betula (probably B. pendula) started at ~9,800 cal. b.p., more than 1,000 years later than at similar elevations in the Central and Southern Alps, indicating cooler temperatures and/or a high seasonality. Highest biomass production and forest position of ~2,100–2,300 m a.s.l. are inferred during the Holocene Thermal Maximum from 7,000 to 5,000 cal. b.p. With the onset of pastoralism and transhumance at 6,800–6,500 cal. b.p., human impact became an important factor in the vegetation dynamics at Iffigsee. This early evidence of pastoralism is documented by the presence of grazing indicators (pollen, spores), as well as a wealth of archaeological finds at the nearby mountain pass of Schnidejoch. Human and fire impact during the Neolithic and Bronze Ages led to the establishment of pastures and facilitated the expansion of Picea abies and Alnus viridis. We expect that in mountain areas with land abandonment, the treeline will react quickly to future climate warming by shifting to higher elevations, causing drastic changes in species distribution and composition as well as severe biodiversity losses.

Software-based detection of atrial fibrillation in long-term ECGs

Background Atrial fibrillation (AF) is common and may have severe consequences. Continuous long-term electrocardiogram (ECG) is widely used for AF screening. Recently, commercial ECG analysis software was launched, which automatically detects AF in long-term ECGs. It has been claimed that such tools offer reliable AF screening and save time for ECG analysis. However, this has not been investigated in a real-life patient cohort. Objective To investigate the performance of automatic software-based screening for AF in long-term ECGs. Methods Two independent physicians manually screened 22,601 hours of continuous long-term ECGs from 150 patients for AF. Presence, number, and duration of AF episodes were registered. Subsequently, the recordings were screened for AF by an established ECG analysis software (Pathfinder SL), and its performance was validated against the thorough manual analysis (gold standard). Results Sensitivity and specificity for AF detection was 98.5% (95% confidence interval 91.72%–99.96%) and 80.21% (95% confidence interval 70.83%–87.64%), respectively. Software-based AF detection was inferior to manual analysis by physicians (P < .0001). Median AF duration was underestimated (19.4 hours vs 22.1 hours; P < .001) and median number of AF episodes was overestimated (32 episodes vs 2 episodes; P < .001) by the software. In comparison to extensive quantitative manual ECG analysis, software-based analysis saved time (2 minutes vs 19 minutes; P < .001). Conclusion Owing to its high sensitivity and ability to save time, software-based ECG analysis may be used as a screening tool for AF. An additional manual confirmatory analysis may be required to reduce the number of false-positive findings.

Chronostratigraphy of the 600,000 year old continental record of Lake Van

Lake Van sediment cores from the Ahlat Ridge and Northern Basin drill sites of the ICDP project PALEOVAN contain a wealth of information about past environmental processes. The sedimentary sequence was dated using climatostratigraphic alignment, varve chronology, tephrostratigraphy, argon-argon single-crystal dating, radiocarbon dating, magnetostratigraphy, and cosmogenic nuclides. Based on the lithostratigraphic framework, the different age constraints are compiled and a robust and precise chronology of the 600,000 year-old Lake Van record is constructed. Proxy records of total organic carbon content and sediment color, together with the calcium/potassium-ratios and arboreal pollen percentages of the 174-meter-long Ahlat Ridge record, mimic the Greenland isotope stratotype (NGRIP). Therefore, the proxy records are systematically aligned to the onsets of interstadials reflected in the NGRIP or synthesized Greenland ice-core stratigraphy. The chronology is constructed using 27 age control points derived from visual synchronization with the GICC05 timescale, an absolutely-dated speleothem record (e.g., Hulu, Sanbao, Linzhu cave) and the Epica Dome C timescale. In addition, the uppermost part of the sequence is complemented with four ages from Holocene varve chronology and two calibrated radiocarbon ages. Furthermore, nine argon-argon ages and a comparison of the relative paleointensity record of the magnetic field with reference curve PISO-1500 confirm the accuracy of the age model. Also the identification of the Laschamp event via measurements of 10Be in the sediment confirms the presented age model. The chronology of the Ahlat Ridge record is transferred to the 79-meter-long event-corrected composite record from the Northern Basin and supplemented by additional radiocarbon dating on organic marco-remains. The basal age of the Northern Basin record is estimated at ~90 ka. The variations of the time series of total organic carbon content, the Ca/K ratio, and the arboreal pollen percentages illustrate that the presented chronology and paleoclimate data are suited for reconstructions and modeling of the Quaternary and Pleistocene climate evolution in the Near East at millennial timescales. Furthermore, the chronology of the last 250 kyr can be used to test other dating techniques.

Into the abyss of Lake Geneva: the elemo interdisciplinary field investigation using the MIR submersibles

In summer 2011, the two Russian MIR sub- mersibles were brought to Switzerland to perform deep water dives in Lake Geneva. Research teams from several environmental science institutes, both national and inter- national, participated in this interdisciplinary effort to investigate the deeper parts of Lake Geneva. Using the MIRs allowed the scientists to see and precisely select the sites where they could extract specific sediment cores and carry out detailed in situ measurements at the sediment– water boundary. One focus site was the surrounding of the outlet of the wastewater treatment plant of the City of Lausanne, which discharges into the Vidy Bay. The investigations concentrated on the pollution of the local sediments, pollution-related ecotoxicological risks, micro- bial activity and spreading and removal of the effluents from the bay to the open waters of the lake. The other focus site was the Rhoˆne River delta and its subaquatic canyons, which formed as a result of the long-term interplay of the deposition of river-borne sediments and flood-triggered canyon erosion events.

Lake Van deep drilling project PALEOVAN

A complete succession of the lacustrine sediment sequence deposited during the last ∼600,000 years in Lake Van, Eastern Anatolia (Turkey) was drilled in 2010 supported by the International Continental Scientific Drilling Program (ICDP). Based on a detailed seismic site survey, two sites at a water depth of up to 360 m were drilled in summer 2010, and cores were retrieved from sub-lake-floor depths of 140 m (Northern Basin) and 220 m (Ahlat Ridge). To obtain a complete sedimentary section, the two sites were multiple cored in order to investigate the paleoclimate history of a sensitive semi-arid region between the Black, Caspian, and Mediterranean seas. This introductory paper provides background information of the deep drilling project and an overview of the studies presented in this special volume by the PALEOVAN science team dealing with chronology, paleomagnetism, paleoenvironmental proxies, geophysical and petrophysical investigations as well as pore-water and fluid transport.

Alpine lacustrine varved record reveals summer temperature as main control of glacier fluctuations over the past 2250 years

Glacier fluctuations are a key indicator of changing climate. Their reconstruction beyond historical times unravels glacier variability and its forcing factors on long time scales, which can considerably improve our understanding of the climate–glacier relationship. Here, we present a 2250-year-long reconstruction of particle-mass accumulation rates recorded in the lacustrine sediments of Lake Trüebsee (Central Swiss Alps) that are directly related to glacier extent, thus reflecting a continuous record of fluctuations of the upstream-located Titlis Glacier. Mass accumulation rate values show strong centennial to multi-centennial fluctuations and reveal 12 well-pronounced periods of enhanced values corresponding to times of maximum extent of the neighboring Lower Grindelwald Glacier. This result supports previous studies of proglacial lake sediments that documented high mass accumulation rate values during glacier advances. The strong variability in the Lake Trüebsee mass accumulation rate record thus represents a highly sensitive paleoclimatic archive, which mirrors rapid and pronounced feedbacks of Titlis Glacier to climatic changes over the past 2250years. The comparison of our data with independent paleo-temperature reconstructions from tree rings suggests that variations in mean summer temperature were the primary driving factor of fluctuations of Titlis Glacier. Also, advances of Titlis Glacier occurred during the grand solar minima (Dalton, Maunder, Spörer, Wolf) of the last millennium. This relation of glacier extent with summer temperature reveals strong evidence that the mass balance of this Alpine glacier is primarily controlled by the intensity of glacier melting during summer.

Bathymetry of Lake Constance - State-of-the-art in surveying a large lake

In 2014 the by far largest German lake has been newly surveyed. The transnational project is funded by the European Union and delivers a detailed 3D-model of the lake- floor. The German project name is »Tiefenschärfe – Hochauflösende Vermessung Bo- densee«, which in English roughly means: high-resolution survey of Lake Constance. The German term »Tiefenschärfe« (in optics and photography: depth of field) plays with the meanings of »Tiefe« (depth) and »Schärfe« (sharpness). The result of the sur- vey shall be a clear and sharp image of the deep and shallow lake- floor. At present the LiDAR and multibeam data are still processed, but first results are presented in this article.

Mass Movement-Induced Tsunami Hazard on Perialpine Lake Lucerne (Switzerland): Scenarios and Numerical Experiments

Previous studies of the sediments of Lake Lucerne have shown that massive subaqueous mass movements affecting unconsolidated sediments on lateral slopes are a common process in this lake, and, in view of historical reports describing damaging waves on the lake, it was suggested that tsunamis generated by mass movements represent a considerable natural hazard on the lakeshores. Newly performed numerical simulations combining two-dimensional, depth-averaged models for mass-movement propagation and for tsunami generation, propagation and inunda- tion reproduce a number of reported tsunami effects. Four analysed mass-movement scenarios—three based on documented slope failures involving volumes of 5.5 to 20.8 9 106 m3—show peak wave heights of several metres and maximum runup of 6 to [10 m in the directly affected basins, while effects in neighbouring basins are less drastic. The tsunamis cause large-scale inundation over distances of several hundred metres on flat alluvial plains close to the mass-movement source areas. Basins at the ends of the lake experience regular water-level oscillations with characteristic periods of several minutes. The vulnerability of potentially affected areas has increased dramatically since the times of the damaging historical events, recommending a thorough evaluation of the hazard.