Effect of substrate-temperature on the microstructure of thin niobium films

Niobium films with constant thickness have been deposited on sapphire (11 $($) over bar$$ 20) by electron-beam evaporation at different substrate; temperatures (150 degrees C less than or equal to T-S less than or equal to 750 degrees C). The samples were characterized by X-ray diffraction and resistivity measurements. X-ray reflectivity shows that all films are covered with an oxide layer of about 20 Angstrom in ambient atmosphere. The (110) texture at high T-S decreases towards lower T-S, accompanied by an increasing surface roughness. Below T-S = 350 degrees C the grain size in the growth direction becomes smaller than the film thickness and a relaxation of intrinsic stress is observed. A transition from a columnar growth structure to a fine grained microstructure is inferred. The change of the microstructure with T-S is probably due to the temperature dependent grain boundary mobility during the deposition process

Superconducting decay length in a ferromagnetic metal

The complex decay length xi characterizing penetration of superconducting correlations into a ferromagnet due to the proximity effect is studied theoretically in the frame of the linearized Eilenberger equations. The real part xi_1 and imaginary part xi_2 of the decay length are calculated as functions of exchange energy and the rates of ordinary, spin flip and spin orbit electronic scattering in a ferromagnet. The lengths xi_1,2 determine the spatial scales of, respectively, decay and oscillation of a critical current in SFS Josephson junctions in the limit of large distance between superconducting electrodes. The developed theory provides the criteria of applicability of the expressions for xi_1 and xi_2 in the dirty and the clean limits which are commonly used in the analysis of SF hybrid structures.Comment: 5 pages, 3 figure

Features of Toxoplasma gondii reactivation after allogeneic hematopoietic stem-cell transplantation in a high seroprevalence setting

We performed a single-centre retrospective study to evaluate the effectiveness of Toxoplasma gondii prevention strategies after allogeneic stem-cell transplantation. The charts of 138 allogeneic stem-cell recipients over a 4-year period were reviewed. Forty-nine percent of patients were not receiving optimal trimethoprim–sulfamethoxazole (TMP–SMZ) prophylaxis at day +30, mainly due to persistent cytopenia. Six months after transplantation, the rate of toxoplasmosis reactivation was 11.6%, including nine cases of Toxoplasma infection and seven cases of Toxoplasma disease. Fifty-six percent of cases of reactivation occurred before day +30. Thirty-eight percent occurred in patients receiving atovaquone prophylaxis. In 57% of patients presenting with Toxoplasma disease, signs of disease were present at first evidence of Toxoplasma DNA in peripheral blood samples. This study illustrates the limitations inherent to currently used toxoplasmosis prevention strategies and argues for the use of a combined prophylactic and preemptive approach. After performing the initial study, we limited the use of atovaquone in favour of TMP–SMZ when possible, and implemented an early prevention strategy consisting of the introduction of prophylaxis starting on day of engraftment. Over the following 16 months, 88.9% of eligible Toxoplasma-seropositive patients were receiving TMP–SMZ at day +30, and the rate of early Toxoplasma reactivation was 1.5%

<em>Escherichia coli</em> bacteraemia in pregnant women is life-threatening for foetuses

International audienceIn order to improve knowledge on Escherichia coli bacteraemia during pregnancy, we studied clinical data and performed molecular characterization of strains for 29 E. coli bacteraemia occurring in pregnant women. Bacteraemia mostly occurred in the third trimester of pregnancy (45%) and was community-acquired (79%). Portals of entry were urinary (55%) and genital (45%). E. coli strains belonged mainly to phylogroups B2 (72%) and D (17%). Four clonal lineages (i.e. sequence type complex (STc) 73, STc95, STc12 and STc69) represented 65% of the strains. The strains exhibited a high number of virulence factor coding genes (10 (3-16)). Six foetuses died (27%), five of them due to bacteraemia of genital origin (83%). Foetal deaths occurred despite adequate antibiotic regimens. Strains associated with foetal mortality had fewer virulence factors (8 (6-10)) than strains involved in no foetal mortality (11 (4-12)) (p 0.02). When comparing E. coli strains involved in bacteraemia with a urinary portal of entry in non-immunocompromised pregnant vs. non-immunocompromised non-pregnant women from the COLIBAFI study, there was no significant difference of phylogroups and virulence factor coding genes. These results show that E. coli bacteraemia in pregnant women involve few highly virulent clones but that severity, represented by foetal death, is mainly related to bacteraemia of genital origin

Clinical and microbiological determinants of severe and fatal outcomes in patients infected with Enterobacteriaceae producing extended-spectrum β-lactamase

Although extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae have become a worldwide public health concern, little is known regarding the clinical course of colonized or infected individuals. Our objective was to characterize the determinants of fatal outcomes related to ESBL-producing microorganisms at a large hospital in Paris, France. In 2012–2013, all consecutive patients with clinical samples testing positive for ESBL-producing Enterobacteriaceae at Saint-Antoine Hospital were identified. Patient clinical data were obtained at hospital entry, while information on intensive care unit (ICU) admissions and death were prospectively collected. Risk-factors for fatal 1-year outcomes were assessed using logistic regression. In total, 643/4684 (13%) ESBL-positive samples were observed, corresponding to 516 episodes (n = 206, 40% treated) among 330 patients. Most episodes were nosocomial-related (n = 347/516, 67%) involving Escherichia coli (n = 232/516, 45%) or Klebsiella pneumoniae (n = 164/516, 32%). Empirical antibiotic therapy was adequate in 89/206 (43%) infections, while the median length of hospital stay was 30 days [interquartile range (IQR) = 11–55] and 39/201 (19%) were admitted to the ICU. Overall, 104/241 patients (43%) with available data died within 1 year. In the multivariable analysis, 1-year death was associated with age >80 years (p = 0.01), concomitant comorbidity (p = 0.001), nosocomial-acquired infection (p = 0.002), and being infected rather than colonized (p < 0.001). In this series of patients with identified samples of ESBL-producing Enterobacteriaceae, hospital burden was large and 1-year mortality rates high. Understanding which patients in this setting would benefit from broad-spectrum empirical antibiotic therapy should be further examined