Biosafety level | EPFL Graph Search

A biosafety level (BSL), or pathogen/protection level, is a set of biocontainment precautions required to isolate dangerous biological agents in an enclosed laboratory facility. The levels of containment range from the lowest biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4). In the United States, the Centers for Disease Control and Prevention (CDC) have specified these levels in a publication referred to as BMBL. In the European Union, the same biosafety levels are defined in a directive. In Canada the four levels are known as Containment Levels. Facilities with these designations are also sometimes given as P1 through P4 (for pathogen or protection level), as in the term P3 laboratory. At the lowest level of biosafety, precautions may consist of regular hand-washing and minimal protective equipment. At higher biosafety levels, precautions may include airflow systems, multiple containment rooms, sealed containers, positive pressure personnel suits, established protocols f

Long-range transport of pollution to Europe

Marion Auvray

Ozone (O3) and aerosols are harmful to human health. Long-range transport sources contribute to the background levels upon which local pollution builds. The goal of this thesis is to describe and quantify the respective contribution of local and long-range transported sources to the O3 and aerosol budget in the framework of European air quality management. This issue is examined using a global model of chemistry and transport, the GEOS-Chem model, constrained by several experimental datasets (e.g. trace gases and aerosol distributions, aerosol optical depth, particulate matter concentrations) taken from field experiments, ground-based sites and satellite. The capabilities of the model to reproduce O3 and aerosol patterns is first examined. The model reproduces well in general the distribution of O3 and related species over the North Atlantic/Europe area. The simulation of particulate matter smaller than 2.5 μm (PM2.5) and aerosol optical depth (AOD) over Europe is also satisfying in general, but this may reflect some compensating errors between individual components (e.g. underestimate of organic matter, and overestimate of sulphate and dust). Intercomparison between the GEOS-Chem and another global model (MOZECH) also reveals possible problems in the water vapour distribution associated with the processes which drive the vertical lifting of pollutant over continental boundary layers. Despite these (relative) deficiencies, the model provides anyway insights about the contribution of long-range transport on the O3 and aerosol loads over Europe. The impact of continental outflow on the O3 chemical tendencies over oceanic regions is quantified. Net O3 photochemical production in polluted air masses travelling over oceanic areas under the influence of continental outflow is enhanced all-year round compared to the background marine environment by 2 to 6 ppbv/day in the boundary layer and by 1 to 3 ppbv/day in the upper troposphere. The origin of O3 long-range sources and their impact on the European O3 budget, as well as the role of changing emissions on this budget over the pasts decades is further investigated. Import of North American O3 into Europe is mainly controlled by meteorological patterns and by photochemical production over the North Atlantic and thus reaches a maximum in summer. In addition, Asia contributes to long-range transported O3 pollution by the Indian summer monsoon easterly winds during summer. During the monsoon period, convection is strong and associated NOx lightning emissions also contribute to high O3 levels, especially in the Mediterranean basin. North American and Asian anthropogenic pollution contribute substantially to the annual O3 burden (integrated over the whole tropospheric column) over Europe, accounting for 11% and 8%, respectively while the European contribution only accounts for 9%. The increase in Asian emissions from 1980 to 1997 have compensated the local reduction of O3 precursors, especially in the free troposphere. Finally, the aerosol load over Europe and the contribution of long and medium-range sources including anthropogenic and biomass burning pollution from North America and mineral dust from North Africa is examined. The model was used to interpret MODIS (Moderate Resolution Imaging Spectroradiometer) AOD and observations provided by the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign over the North Atlantic and European area. Trans-Atlantic transport of aerosol is controlled by meteorological patterns and scavenging processes and reaches a maximum in spring. North American uxes of aerosols reach Europe at flower altitudes than that of O3 because a larger fraction of aerosols are scavenged in the venting from the boundary layer by frontal passages and deep convection. During high vegetation fire events in the boreal forest of Alaska and Canada, biomass burning pollution could also reach Europe at high altitudes, because a fraction of fire emissions are emitted directly in the free troposphere. Finally, the Saharan region also contributes significantly to the aerosol load over Europe. European sources contribute by 58% and 48% to the surface PM2.5 and column AOD over Europe. The second main sources are the mineral dust which represent in average 20% of the surface PM2.5 and AOD. In summer, North American anthropogenic and biomass burning emissions represent between 2 to 5% of the surface PM2.5 and AOD. The PM2.5 daily standard levels of the World Health organization (WHO) (10 μg/m3) and of the U.S. Environmental Protection Agency (EPA) (65 μg/m3) are often exceeded during dust outbreaks, especially in southern Europe. Long-range transport of anthropogenic and natural pollution is thus an important issue which should be considered in the definition of air quality standards and regulation treaties.

EPFL2006

DNA-based biomaterials for nanoscale controlled modulation of immune cells

Alice Comberlato

Recent advances in the field of nanomaterials demonstrated how their use for vaccination can drastically improve immune responses, mainly by enhancing delivery and uptake of vaccine components. However, our understanding of the connections between presentation of immune-modulatory agents on nanomaterials and cellular responses is still very limited. DNA-based nanostructures evolved as an ideal platform to display ligands with unprecedented nanoscale precision for the investigation and control of ligand-receptor interactions involved in cellular activation, being at the same time a carrier for these therapeutics. With this work, we aim to set the next steps for DNA nanoparticles to become functional structures in medicine and to develop DNA-based nanomaterials to study aspects of the complexity of our immune system.In Chapter 1, the latest developments and key features of immune-engineering nanomaterials for vaccination with nucleic acid adjuvants are summarized. Moreover, we report the importance of ligand spacing as new parameter in multivalent systems for immune modulation and how DNA-based nanomaterials demonstrated the significance of ligand patterns for regulated cellular responses.In Chapter 2, we developed a DNA origami disk-shaped nanoparticle with nanoscale control on ligand presentation, to be used as platform for cellular interaction studies at the single-molecule level. By DNA-PAINT super resolution microscopy, we verified spatial patterns on our nanoparticle, showing that our in silico design matches at the one-nanometer-level with experimental measurements. Additionally, we verified that the oligolysine-PEG protective coating does not hamper the accessibility of functional sites. In Chapter 3, we present a systematic analysis of the effects of surface parameters of DNA-based nanoparticles on cellular uptake. We demonstrated the influence of surface charge, stabilizing coating, fluorophore types, functionalization technique, and particle concentration on material uptake in three different cell models: tumor cells, macrophages, and dendritic cells. Additionally, we showed approaches to reduce the risk of data artifacts in vitro. In Chapter 4, we employed our DNA platform to demonstrate the importance of controlling the spacing of adjuvant presentation on nanoparticles for the activation of immune cells. Exploiting pre-existing crystallography data, we created DNA disk nanoparticles presenting CpG-motif adjuvants in rationally designed spatial patterns to activate Toll-like Receptor 9. We showed that stronger immune activation is achieved when CpG ligands are matching the distance of the binding sites of the active dimer form of the receptor, compared to random presentation or free form of CpG at equal dose. Moreover, we show how linkers for conjugating active molecules to nanomaterials alter the spatial tolerance of binding and cell activation levels. Taken together, our results show that proper receptor targeting and engineering surface parameters for uptake of nanomaterials would help to develop potent and specific immune therapies. The rationally designed and spatially controlled presentation of therapeutics would aid future vaccine strategies to manipulate the immune system at the nanoscale level and to improve dose sparing, limiting toxicity often associated with the use of high doses of drugs.

EPFL2022

A time-of-flight-Mott apparatus for soft x-ray spin resolved photoemission on solid samples

Luca Moreschini

We describe a new spectrometer for spin resolved photoemission from solids in the soft x-ray energy range. It is mounted on the ID08 beamline at the ESRF light source and consists of a time-of-flight (TOF) energy analyzer coupled to a retarding mini-Mott spin polarimeter. It represents a valid alternative to the spin detection system already available on ID08, especially for the acquisition of wide energy regions, where the TOF technique is extremely efficient. By testing the new spectrometer on the 4f levels of Au and on CuO at the Cu L-3 threshold we show that the effective Sherman function and figure of merit achieved are, respectively, S-eff similar or equal to 0.16 and eta similar or equal to 1.3 x 10(-4) and that for certain experiments we obtain a significant gain in intensity with respect to the previous system. (C) 2008 American Institute of Physics.