637 research outputs found
Pilot Experiments with Electrodialysis and Ozonation for the Production of a Fertilizer from Urine
Pilot tests were performed with a process combination of electrodialysis and ozonation for the removal of micropollutants and the concentration of nutrients in urine. In continuous and batch experiments, maximum concentration factors up to 3.5 and 4.1 were obtained, respectively. The desalination capacity did not decrease significantly during continuous operation periods of several weeks. Membrane cleaning after 195 days resulted in approximately 35% increase in desalination rate. The Yeast Estrogen Screen (YES), a bioassay that selectively detects oestrogenic compounds, confirmed that about 90% of the oestrogenic activity was removed by electrodialysis. HPLC analysis showed that ibuprofen was removed to a high extent, while other micropollutants were below the detection limit. In view of the fact that ibuprofen is among the most rapidly transported micropollutants in electrodialysis processes, this result indicates that electrodialysis provides an effective barrier for micropollutants. Standardised plant growth tests were performed in the field with the salt solution resulting from the treatment by electrodialysis and subsequent ozonation. The results show that the plant height is comparable to synthetic fertilisers, but the crop yield is slightly lower. The latter is probably caused by volatilisation losses during field application, which can be prevented by improved application technologies
Formaldehyde Exposure and Asthma in Children: A Systematic Review
Obj e c t i v e: Despite multiple published studies regarding the association between formaldehyde exposure and childhood asthma, a consistent association has not been identified. Here we report the results of a systematic review of published literature in order to provide a more comprehensive picture of this relationship. Data s o u r c e s: After a comprehensive literature search, we identified seven peer-reviewed studies providing quantitative results regarding the association between formaldehyde exposure and asthma in children. Studies were heterogeneous with respect to the definition of asthma (e.g., self-report, physician diagnosis). Most of the studies were cross-sectional
Microseismicity of the Mid-Atlantic Ridge at 7°S-8°15â˛S and at the Logatchev Massif oceanic core complex at 14°40â˛N-14°50â˛N
Lithospheric formation at slow spreading rates is heterogeneous with multiple modalities, favoring symmetric spreading where magmatism dominates or core complex and inside corner high formation where tectonics dominate. We report microseismicity from three deployments of seismic networks at the Mid-Atlantic Ridge (MAR). Two networks surveyed the MAR near 7 degrees S in the vicinity of the Ascension transform fault. Three inside corner high settings were investigated. However, they remained seismically largely inactive and major seismic activity occurred along the center of the median valley. In contrast, at the Logatchev Massif core complex at 14 degrees 45N seismicity was sparse within the center of the median valley but concentrated along the eastern rift mountains just west of the serpentine hosted Logatchev hydrothermal vent field. To the north and south of the massif, however, seismic activity occurred along the ridge axis, emphasizing the asymmetry of seismicity at the Logatchev segment. Focal mechanisms indicated a large number of reverse faulting events occurring in the vicinity of the vent field at 3-5 km depth, which we interpret to reflect volume expansion accompanying serpentinization. At shallower depth of 2-4 km, some earthquakes in the vicinity of the vent field showed normal faulting behavior, suggesting that normal faults facilitates hydrothermal circulation feeding the vent field. Further, a second set of cross-cutting faults occurred, indicating that the surface location of the field is controlled by local fault systems
High-resolution LGM climate of Europe and the Alpine region using the regional climate model WRF
In this study we present a series of sensitivity experiments conducted for the Last Glacial Maximum (LGM, âź21âka) over Europe using the regional climate Weather Research and Forecasting model (WRF). Using a four-step two-way nesting approach, we are able to reach a convection-permitting horizontal resolution over the inner part of the study area, covering central Europe and the Alpine region. The main objective of the paper is to evaluate a model version including a series of new developments better suitable for the simulation of paleo-glacial time slices with respect to the ones employed in former studies. The evaluation of the model is conducted against newly available pollen-based reconstructions of the LGM European climate and takes into account the effect of two main sources of model uncertainty: a different height of continental glaciers at higher latitudes of the Northern Hemisphere and different land cover. Model results are in good agreement with evidence from the proxies, in particular for temperatures. Importantly, the consideration of different ensemble members for characterizing model uncertainty allows for increasing the agreement of the model against the proxy reconstructions that would be obtained when considering a single model realization. The spread of the produced ensemble is relatively small for temperature, besides areas surrounding glaciers in summer. On the other hand, differences between the different ensemble members are very pronounced for precipitation, in particular in winter over areas highly affected by moisture advection from the Atlantic. This highlights the importance of the considered sources of uncertainty for the study of European LGM climate and allows for determining where the results of a regional climate model (RCM) are more likely to be uncertain for the considered case study. Finally, the results are also used to assess the effect of convection-permitting resolutions, at both local and regional scales, under glacial conditions.</p
Massive Stars: Their Environment and Formation
Cloud environment is thought to play a critical role in determining the
mechanism of formation of massive stars. In this contribution we review the
physical characteristics of the environment around recently formed massive
stars. Particular emphasis is given to recent high angular resolution
observations which have improved our knowledge of the physical conditions and
kinematics of compact regions of ionized gas and of dense and hot molecular
cores associated with luminous O and B stars. We will show that this large body
of data, gathered during the last decade, has allowed significant progress in
the understanding of the physical processes that take place during the
formation and early evolution of massive stars.Comment: Pub. Astron. Soc. of Pacific (Invited Review), 95 pages (Latex), 5
pages (tables, Latex), 11 postscript or gif figure
Recommended from our members
Antibiotic knowledge, attitudes, and practices: new insights from cross-sectional rural health behaviour surveys in low- and middle-income South-East Asia
Introduction: Low- and middle-income countries (LMICs) are crucial in the global response to
antimicrobial resistance (AMR), but diverse health systems, healthcare practices, and cultural
conceptions of medicine can complicate global education and awareness-raising campaigns. Social
research can help understand LMIC contexts but remains underrepresented in AMR research.
Objective: To (1) describe antibiotic-related knowledge, attitudes, and practices of the general
population in two LMICs and to (2) assess the role of antibiotic-related knowledge and attitudes on
antibiotic access from different types of healthcare providers.
Design: Observational study: cross-sectional rural health behaviour survey, representative on the
population level.
Setting: General rural population in Chiang Rai (Thailand) and Salavan (Lao PDR), surveyed between
November 2017 and May 2018.
Participants: 2141 adult members (âĽ18 years) of the general rural population, representing 712,000
villagers.
Outcome measures: Antibiotic-related knowledge, attitudes, and practices across sites and healthcare
access channels.
Findings: Villagers were aware of antibiotics (Chiang Rai: 95.7%; Salavan: 86.4%; p<0.001) and drug
resistance (Chiang Rai: 74.8%; Salavan: 62.5%; p<0.001), but the usage of technical concepts for
antibiotics was dwarfed by local expressions like âanti-inflammatory medicineâ in Chiang Rai (87.6%;
95% confidence interval [CI]: 84.9â90.0) and âampiâ in Salavan (75.6%; 95% CI: 71.4â79.4).
Multivariate linear regression suggested that attitudes against over-the-counter antibiotics were linked
to 0.12 additional antibiotic use episodes from public healthcare providers in Chiang Rai (95% CI:
0.01 â 0.23) and 0.53 in Salavan (95% CI: 0.16 â 0.90).
Conclusions: Locally specific conceptions and counter-intuitive practices around antimicrobials can
complicate AMR communication efforts and entail unforeseen consequences. Overcoming
âknowledge deficitsâ alone will therefore be insufficient for global AMR behaviour change. We call
for an expansion of behavioural AMR strategies towards âAMR-sensitive interventionsâ that address
context-specific upstream drivers of antimicrobial use (e.g. unemployment insurance) and complement
education and awareness campaigns
Effect of Weld Schedule on the Residual Stress Distribution of Boron Steel Spot Welds
Press-hardened boron steel has been utilized in anti-intrusion systems in automobiles, providing high strength and weight-saving potential through gage reduction. Boron steel spot welds exhibit a soft heat-affected zone which is surrounded by a hard nugget and outlying base material. This soft zone reduces the strength of the weld and makes it susceptible to failure. Additionally, different welding regimes lead to significantly different hardness distributions, making failure prediction difficult. Boron steel sheets, welded with fixed and adaptive schedules, were characterized. These are the first experimentally determined residual stress distributions for boron steel resistance spot welds which have been reported. Residual strains were measured using neutron diffraction, and the hardness distributions were measured on the same welds. Additionally, similar measurements were performed on spot welded DP600 steel as a reference material. A correspondence between residual stress and hardness profiles was observed for all welds. A significant difference in material properties was observed between the fixed schedule and adaptively welded boron steel samples, which could potentially lead to a difference in failure loads between the two boron steel welds
- âŚ