Thulium and ytterbium-doped titanium oxide thin films deposited by ultrasonic spray pyrolysis

Thin films of thulium and ytterbium-doped titanium oxide were grown by metal-organic spray pyrolysis deposition from titanium(IV)oxide bis(acetylacetonate), thulium(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and ytterbium(III) tris(acetylacetonate). Deposition temperatures have been investigated from 300{\deg}C to 600{\deg}C. Films have been studied regarding their crystallity and doping quality. Structural and composition characterisations of TiO2:Tm,Yb were performed by electron microprobe, X-ray diffraction and Fourier transform infrared spectroscopy. The deposition rate can reach 0.8 \mum/h. The anatase phase of TiO2 was obtained after synthesis at 400{\deg}C or higher. Organic contamination at low deposition temperature is eliminated by annealing treatments.Comment: 6 pages, 6 figure

Thulium and ytterbium-doped titania thin films deposited by MOCVD

In this study we synthesized thin films of titanium oxide doped with thulium and/or ytterbium to modify the incident spectrum on the solar cells. This could be achieved either by photoluminescence up-converting devices, or down-converting devices. As down-converter thin films our work deals with thulium and ytterbium-doped titanium dioxide. Thulium and ytterbium will act as sensitizer and emitter, respectively. The rare-earth doped thin films are deposited by aerosol-assisted MOCVD using organo-metallic precursors such as titanium dioxide acetylacetonate, thulium and ytterbium tetramethylheptanedionate solved in different solvents. These films have been deposited on silicon substrates under different deposition conditions (temperature and dopant concentrations for example). Adherent films have been obtained for deposition temperatures ranging from 300{\deg}C to 600{\deg}C. The deposition rate varies from 0.1 to 1 \mu m/h. The anatase phase is obtained at substrate temperature above 400{\deg}C. Further annealing is required to exhibit luminescence and eliminate organic remnants of the precursors. The physicochemical and luminescent properties of the deposited films were analyzed versus the different deposition parameters and annealing conditions. We showed that absorbed light in the near-UV blue range is re-emitted by the ytterbium at 980 nm and by a thulium band around 800 nm.Comment: 4 pages, 6 figures, proceedin

Expert consensus on monitoring antimicrobial stewardship in French nursing homes using assessed reimbursement database indicators

Objectives Monitoring the appropriateness of antibiotic prescriptions with indicators based on reimbursement data is required to guide antibiotic stewardship (AMS) interventions in nursing homes (NHs). Quantity metrics (QMs) monitor the volume of prescriptions while proxy indicators (PIs) reflect the appropriateness of antibiotic use. Our objectives were: (i) to provide a relevant consensual set of indicators to be used in French NHs; and (ii) to assess the feasibility of their implementation at the national and local scale. Methods Nine French professional organizations implicated in AMS in NHs were asked to nominate at least one member to create a national expert panel of 20 physicians. Twenty-one recently published QMs and 11 PIs were assessed by the expert panel. Indicators were evaluated using a RAND-modified Delphi procedure comprising two online surveys and a videoconference meeting. Indicators were kept in the final list if >70% of stakeholders validated their relevance for estimating the volume (QMs) and appropriateness (PIs) of prescriptions. Results Of the 21 QM indicators submitted to the panel, 14 were selected, describing the consumption of antibiotics overall (n = 3), broad-spectrum (n = 6) and second-line antibiotics (n = 2). The three remaining QMs evaluated the route of administration (n = 1) and urine culture prescriptions (n = 2). Ten PIs (six modified, two rejected, one new) were selected to assess the appropriateness of prescriptions for urinary tract infections (n = 2), seasonal variations in prescriptions (n = 2), repeated prescriptions of fluoroquinolones (n = 1), cephalosporins’ route of administration (n = 1), duration of treatment (n = 1), rate of second-line antibiotics (n = 1), co-prescriptions with non-steroidal anti-inflammatory drugs (n = 1), and flu vaccine coverage (n = 1). The panel was in favour of using these indicators for regional and facility level AMS programmes (91%), feedback to NH prescribers (82%), benchmarking by health authorities (55%) and public reporting at the facility level (9%). Conclusions This consensual list of indicators, covering a wide range of frequent clinical situations, may be used as part of the French national AMS strategy for monitoring antibiotic prescriptions in NHs at the national and local levels. Regional AMS networks might manage this selected list to guide personalized action plans with concrete objectives of reducing the quantity and improving the quality of antibiotic prescriptions

On the magnetism of Ln{2/3}Cu{3}Ti{4}O{12} (Ln = lanthanide)

The magnetic and thermodynamic properties of the complete Ln$_{2/3}$Cu$_3$Ti$_4$O$_{12}$ series were investigated. Here $Ln$ stands for the lanthanides La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. %Most of the compounds were prepared as single phase polycrystalline powder %without any traces of impurities. Marginal amounts of %impurities $(< 2$ were detected $Ln=$ Gd, Er, and Tm. %Significant amounts of impurity phases were found for $Ln=$ Ce and Yb. All the samples investigated crystallize in the space group $Im\bar{3}$ with lattice constants that follow the lanthanide contraction. The lattice constant of the Ce compound reveals the presence of Ce$^{4+}$ leading to the composition Ce$_{1/2}$Cu$_3$Ti$_4$O$_{12}$. From magnetic susceptibility and electron-spin resonance experiments it can be concluded that the copper ions always carry a spin $S=1/2$ and order antiferromagnetically close to 25\,K. The Curie-Weiss temperatures can approximately be calculated assuming a two-sublattice model corresponding to the copper and lanthanide ions, respectively. It seems that the magnetic moments of the heavy rare earths are weakly coupled to the copper spins, while for the light lanthanides no such coupling was found. The $4f$ moments remain paramagnetic down to the lowest temperatures, with the exception of the Tm compound, which indicates enhanced Van-Vleck magnetism due to a non-magnetic singlet ground state of the crystal-field split $4f$ manifold. From specific-heat measurements we accurately determined the antiferromagnetic ordering temperature and obtained information on the crystal-field states of the rare-earth ions. The heat-capacity results also revealed the presence of a small fraction of Ce$^{3+}$ in a magnetic $4f^1$ state.Comment: 10 pages, 10 figure

Spectres vibrationnels des silicates et germanates renfermant des anneaux, M3O9 (M Si, Ge)-I. Attribution des fréquences caractéristiques de l'anneau M3O9, dans les composés de type bénitoïte, wadéite et tétragermanate

A number of cyclo-silicates and germanates with the benitoïte, wadeite or tetra-germanate structure have been investigated by i.r. and Raman spectroscopy, so as to evidence the essential spectroscopic features of the Si3O9 and Ge3O9 rings and to show how these features are modified under the influence of a change of structure, with or without modification of the local symmetry of the ring. One band in the i.r. spectrum and two bands in the Raman spectrum have been found to be highly specific of the ring structure. The two Raman bands are observed in the 600-500 cm-1 region for the silicates, and 550-450 cm-1 region for the germanates; they correspond to bending motions of the ring, involving a predominant displacement of the ring oxygens, and no large displacement of the cations, as evidenced by the small 28Si-30Si isotopic shift. The characteristic i.r. band is observed in the 760-700 cm-1 region for the silicates, and the 550-500 cm-1 region for the germanates, with a large (14 cm-1) 28Si-30Si isotopic shift. This important mass effect of the cation is also reflected in the large frequency ratio ν(silicate) ν(germanate). This band is unique as long as the ring has the local C3h symmetry, irrespective of the crystal structure (benitoïte or wadeite); but it is split into a multiplet for distorted rings. It is thus a sensitive means of detecting the local symmetry of the ring. © 1975