Neutrino tomography - Learning about the Earth's interior using the propagation of neutrinos

Because the propagation of neutrinos is affected by the presence of Earth matter, it opens new possibilities to probe the Earth's interior. Different approaches range from techniques based upon the interaction of high energy (above TeV) neutrinos with Earth matter, to methods using the MSW effect on the neutrino oscillations of low energy (MeV to GeV) neutrinos. In principle, neutrinos from many different sources (sun, atmosphere, supernovae, beams etc.) can be used. In this talk, we summarize and compare different approaches with an emphasis on more recent developments. In addition, we point out other geophysical aspects relevant for neutrino oscillations.Comment: 22 pages, 9 figures. Proceedings of ``Neutrino sciences 2005: Neutrino geophysics'', December 14-16, 2005, Honolulu, USA. Minor changes, some references added. Final version to appear in Earth, Moon, and Planet

Antimicrobial use in European acute care hospitals: results from the second point prevalence survey (PPS) of healthcare-associated infections and antimicrobial use, 2016 to 2017

Antimicrobial agents used to treat infections are life-saving. Overuse may result in more frequent adverse effects and emergence of multidrug-resistant microorganisms. In 2016-17, we performed the second point-prevalence survey (PPS) of healthcare-associated infections (HAIs) and antimicrobial use in European acute care hospitals. We included 1,209 hospitals and 310,755 patients in 28 of 31 European Union/European Economic Area (EU/EEA) countries. The weighted prevalence of antimicrobial use in the EU/EEA was 30.5% (95% CI: 29.2-31.9%). The most common indication for prescribing antimicrobials was treatment of a community-acquired infection, followed by treatment of HAI and surgical prophylaxis. Over half (54.2%) of antimicrobials for surgical prophylaxis were prescribed for more than 1 day. The most common infections treated by antimicrobials were respiratory tract infections and the most commonly prescribed antimicrobial agents were penicillins with beta-lactamase inhibitors. There was wide variation of patients on antimicrobials, in the selection of antimicrobial agents and in antimicrobial stewardship resources and activities across the participating countries. The results of the PPS provide detailed information on antimicrobial use in European acute care hospitals, enable comparisons between countries and hospitals, and highlight key areas for national and European action that will support efforts towards prudent use of antimicrobials

The relationship between tunable optical absorption and SERS activity of Ag/ZnO nanocomposites

The optical characteristics of Ag/ZnO composite nanostructures have long been of particular interest and, thus, the subject of broad experimental and theoretical studies. This work is focused on the synthesis and properties of Ag/ZnO nanocomposites and demonstrates the possibility of their application as active substrates for surface-enhanced Raman spectroscopy (SERS) in detection of pesticides. The samples were synthesized by pulsed laser deposition (PLD) of ZnO thin films, followed by Ag+-ion implantation in the ZnO matrix and by laser annealing of the heterostructures produced. The morphology and properties of the samples were studied with respect to the processing parameters. The optical absorption studies revealed the existence of tunable surface plasmon resonance of silver nanoparticles in the ZnO matrix. Theoretical calculations of the optical properties, as extinction, absorption and scattering efficiencies, were performed based on a generalized multi-particle Mie (GMM) approach. The simulated system assumed in this comparative study consists of a surface-embedded ensemble of silver nanoparticles in a ZnO surrounding media and in air. The simulated structures were reproduced from the corresponding SEM images after laser annealing at 355 nm and 532 nm

Fabrication of Ag/ZnO nanostructures for SERS applications

© 2019 Elsevier B.V. A novel and effective approach is suggested for fabrication of composite Ag/ZnO nanostructures for surface-enhanced Raman scattering (SERS) by combining laser and ion implantation techniques. The study explores the relation between the nanoscopic features of the prepared Ag/ZnO nanocomposites and their effectiveness as SERS active substrates. The ZnO thin films are grown by pulsed laser deposition (PLD). Ag+-ion implantation is used for surface synthesis of Ag nanoparticles (NPs) in the ZnO matrix. The implanted samples are annealed by a Nd:YAG laser at various parameters. The surface morphology, composition and optical properties of the nanocomposites are studied before and after the ion and laser modifications. The possibility to apply these structures to ammonium nitrate detection is investigated by identifying the most suitable conditions for laser annealing of the implanted Ag/ZnO structures in view of producing the strongest SERS signal. A comparative Raman study is performed at two laser excitation wavelengths. New results are obtained for different ammonium nitrate (AN) concentrations. The strongest Raman signal of ammonium nitrate is detected for the Ag/ZnO substrate annealed at 532 nm and characterized by a high surface roughness and a wide nanoparticles’ size distribution, where a low surface electron density of silver was obtained

Single-step fabrication of oriented composite nanowires by pulsed laser deposition in magnetic field

In this work, we demonstrate a novel way of fabricating oriented composite nanowires consisting of arranged nanoparticles. The structures are produced by an advanced pulsed laser deposition technology involving the simultaneous ablation of two metal targets, Fe and Ag. The depositions are carried out in air at atmospheric pressure in the presence of a magnetic field by using nanosecond laser pulses delivered by a Nd:YAG laser system operating at its fundamental wavelength. Samples are thus produced composed by iron oxide and silver at different percentage ratios. Their morphology represents nanowires with few tens of microns in length and an orientation predominantly following the direction of the magnetic force lines. The study on the optical properties of the structures thus produced revealed plasmon resonance behavior in their transmission spectra with its position depending on the ratio between the two building materials. UV–vis spectra were also obtained with polarized light. Higher transmission was measured for light polarized perpendicular to the length of the nanowires, compared to the case of polarization parallel to the nanowires. The structures can find applications in the design of novel polarization and magneto-optics devices, as well as in nanoelectronics and spintronics

Direct investigation of the vectorization properties of amphiphilic cyclodextrins in phospholipid films

URL: http://www-spht.cea.fr/articles/s01/005International audiencePhospholipids form very stable Newton Black Films which have some similar properties of real biological membrane. Recently, new cyclodextrin derivatives have been synthesised and were shown to exhibit strong amphiphilic properties. In this paper, we simulate the action on phospholipids of these new amphiphilic cyclodextrins. Mixed phospholipids/cyclodextrin derivatives films were prepared and studied using X-ray reflectivity for various phospholipids/ cyclodextrins ratios. A molar ratio of 3 affords a highly stable film for which the molecular structure has been investigated in details. The cyclodextrin molecular carrier property is also addressed through the addition of a neuroleptic drug: Dosulepin, to this complex film architecture, as an example of potential application