Effect of the over-ageing treatment on the mechanical properties of AA2024 aluminum alloy.

The evolution of the hardness of the over-ageing AA2024 alloy scale was followed by measurements of Vickers hardness. The nanoindentation is adapted to the determination of elastoplastic properties (hardness and Young’s modulus) of the matrix and also of coarse intermetallic precipitates. Influence of the artificial over-ageing time to hardness and to mechanical properties as the local scale was investigated

Heuristic for the preemptive asymmetric stacker crane problem

International audienceIn this paper, we deal with the preemptive asymmetric stacker crane problem in an heuristic way. We first present some theoretical results which allow us to turn this problem into a specific tree design problem. We next derive from this new representation a simple, efficient local search heuristic, as well as an original LIP model. We conclude by presenting experimental results which aim at both testing the efficiency of our heuristic and at evaluating the impact of the preemption hypothesis

Assessment of the genotoxicity of quinolone and fluoroquinolones contaminated soil with the Vicia faba micronucleus test

The genotoxicity of quinolone and fluroquinolones was assessed using the micronucleus (MN) test on Viciafaba roots by direct contact exposure to a solid matrix. Plants were exposed to quinolones (nalidixic acid) and fluoroquinolones (ciprofloxacin and enrofloxacin) alone or mixed with artificially contaminatedsoils. Four different concentrations of each of these antibiotics were tested (0.01, 0.1, 1 and 10 mg/Kg) for nalidixic acid and (0.005, 0.05, 0.5 and 5 mg/Kg) for ciprofloxacin and enrofloxacin. These antibiotics were also used in mixture. Exposure of Vicia faba plants to each antibiotic at the highest two concentrations showed significant MN induction. The lowest two concentrations had no significant genotoxic effect. The mixture of the three compounds induced a significant MN induction whatever the mixture tested, from 0.02 to 20 mg/Kg. The results indicated that a similar genotoxic effect was obtained with the mixture at 0.2 mg/Kg in comparison with each molecule alone at 5–10 mg/Kg. Data revealed a clear synergism of these molecules on Vicia faba genotoxicity

Performance characteristics of a rapid immunochromatographic assay for detection of pandemic influenza A (H1N1) virus in children

Rapid tests for diagnosis of influenza are valuable assets in the management of influenza in pediatric patients. However, test performance fluctuates with virus subtypes. We assessed the test characteristics of Influenzatop®, a rapid immunochromatographic influenza A and B test, in detecting pandemic 2009 influenza A (H1N1) in children up to 18years of age, using reverse transcriptase polymerase chain reaction (RT-PCR) as the gold standard. Three hundred and one pediatric outpatients with influenza-like illness were included into the study. Overall sensitivity of Influenzatop® was 64% (95% confidence interval (CI) 56-71%) but increased to 92% (95% CI, 80-97%) when performed between 24 and 48h after onset of symptoms. Positive Influenzatop® results among RT-PCR-positive patients were associated with higher viral load. No significant variation in test performance could be detected when analyzed by age and high versus low prevalence period. Overall test specificity was 99% (95% CI, 95-100%); positive and negative predictive values were 98% (95% CI, 93-99%) and 70% (95% CI, 63-76%), respectively. Conclusion: Influenzatop® rapid influenza test is a sound tool in the diagnosis of H1N1 in pediatric patients when employed 24-48h after onset of symptom

Performance characteristics of a rapid immunochromatographic assay for detection of pandemic influenza A (H1N1) virus in children.

UNLABELLED Rapid tests for diagnosis of influenza are valuable assets in the management of influenza in pediatric patients. However, test performance fluctuates with virus subtypes. We assessed the test characteristics of Influenzatop®, a rapid immunochromatographic influenza A and B test, in detecting pandemic 2009 influenza A (H1N1) in children up to 18 years of age, using reverse transcriptase polymerase chain reaction (RT-PCR) as the gold standard. Three hundred and one pediatric outpatients with influenza-like illness were included into the study. Overall sensitivity of Influenzatop® was 64% (95% confidence interval (CI) 56-71%) but increased to 92% (95% CI, 80-97%) when performed between 24 and 48 h after onset of symptoms. Positive Influenzatop® results among RT-PCR-positive patients were associated with higher viral load. No significant variation in test performance could be detected when analyzed by age and high versus low prevalence period. Overall test specificity was 99% (95% CI, 95-100%); positive and negative predictive values were 98% (95% CI, 93-99%) and 70% (95% CI, 63-76%), respectively. CONCLUSION Influenzatop® rapid influenza test is a sound tool in the diagnosis of H1N1 in pediatric patients when employed 24-48 h after onset of symptoms

Study of the influence of the artificial ageing temperature on the AA2024 alloy microstructure

For the last 30 years, AA2024 aluminum alloy was very used as structural material in the aerospace industry due to its low density and good mechanical strength. The phenomenon of precipitation hardening in aluminum alloys takes place at relatively low temperature and induces the precipitation of intermetallic particles composed of the main alloying elements i.e., copper and magnesium. The fundamental stage of the age-hardening process consists in the acceleration of the decomposition phenomenon of the supersaturated solid solution, resulting in the coarse intermetallic particle precipitation; stage where the mechanical properties reaches the maximum values, but at the cost of a low corrosion resistance. In this paper, the AA2024 alloy microstructure was studied during the over-ageing process. The over-ageing treatment (T7) is supposed to stabilize the microstructure and the mechanical properties to improve the corrosion resistance. The over-ageing treatment consists in a solution treatment at 495±5°C for 1 hour, quenched into cold water and artificial aged. Three different artificial ageing temperatures were studied: 150°C, 175°C and 190°C. The mechanical properties modifications were followed by Vickers macrohardness measurements. The treatment duration for each temperature (36 days for 150°C, 50 hrs for 175°C and 24 hrs for 190°C) was determined by a given macrohardness reduction. To characterize the over-aged AA2024 alloy microstructure, a statistical analysis of the surface fraction and surface density of intermetallic particles was made. The intermetallic particle dimension distribution, depending on the over-ageing temperature, was also observed. To do so, scanning electron microscope observations were carried out and image analyses were performed from backscattered electron images

Application of Kelvin probe Force Microscopy (KFM) to evidence localized corrosion of over-aged aeronautical 2024 aluminum alloy

The 2xxx serie aluminum alloys are characterized by good mechanical performances and low density, however they are susceptible to different forms of localized corrosion: pitting corrosion, intergranular corrosion and stress corrosion cracking. The 2024-T351 aluminum alloy is used in the aircraft industry for numerous applications such as fuselage and door skin. Corrosion damage of the material is also very detrimental for the structural integrity of the aircraft. The presence of coarse intermetallic particles, with a heterogeneous size distribution was found to be responsible for the 2024 susceptibility to localized corrosion. These particles are generally the cause of initiation sites. Presence of micro-defects in the oxide film upon coarse intermetallic particles and the galvanic coupling with the matrix contribute to the development of pitting corrosion. The over-ageing treatment (T7) is supposed to stabilize the microstructure and the mechanical properties to improve the corrosion resistance. The 2024 alloy microstructure after the T7 heat treatment remains very complex. The 2024 alloy corrosion behavior was studied in the over-ageing state for three different temperatures (150, 175 and 190 °C). During the corrosion tests in chloride-containing environment, the behavior of coarse intermetallic particles was found to be different. Thus, the 2024 samples suffer a gradual attack upon S-Al2CuMg particles and finally Al(Cu,Mn,Fe,Si) particles. The corrosion damage was studied by Atomic Force Microscopy (AFM) and Kelvin probe Force Microscopy (KFM). This technique allows simultaneous topographical and electric potential mapping to be obtained. This latest potential was shown to be correlated to the corrosion potential of the 2024 alloy. This study focuses on the variation of the KFM potential of the coarse intermetallic particles and the matrix for the over-ageing conditions (T7). Observations using optical microscope and AFM were also performed to obtain the corrosion rate for each condition. The corrosion rate was correlated to the chemical composition variation of the particles obtained by scanning electron microscope observations and EDS analyses

Disease burden of rotavirus gastroenteritis in children up to 5years of age in two Swiss cantons: paediatrician- and hospital-based surveillance

Rotavirus gastroenteritis (RV GE) is a leading cause of diarrhoea in young children. The purpose of this epidemiological surveillance was to measure the disease burden of RV GE among children <5years of age in two regions of Switzerland, Geneva and Lucerne. One hospital and four paediatricians participated per region. The surveillance lasted from December 2006 to June 2007. The population denominator for calculation of the RV GE incidence rate was the average of the overall study population <5years of age under surveillance during the surveillance period. At the study sites, 513 children with GE were presented. Stool sample was collected and examined in 341 cases, of which 130 were RV positive (38.1%). Informed consent to participate in the study was obtained for 113 RV positive subjects. The overall RV GE incidence rate was 0.97% in Lucerne [lower incidence interval (LCI), 0.71%; upper incidence interval (UCI), 1.2%] compared with 0.65 and in Geneva (LCI, 0.50%; UCI, 0.81%). Disease severity assessments using the Vescari score showed that the RV GE episodes were more severe in Lucerne than in Geneva (14.05 ± 3.05 vs 12.85 ± 2.87), which was confirmed by a higher hospitalisation rate in Lucerne at the study visit (82.9% vs 23.6%). More children had fever in Geneva than in Lucerne (42.9% vs 26.8%), and more children were hospitalised during the follow-up period in Geneva than in Lucerne (14.5% vs 2.5%). Genotyping of RV positive stool samples revealed that both G1 and P8 were the most prevalent types in both regions. There was a statistically significant difference in the distribution frequency of G1 between the two regions (p = 0.039). Assessment of health economic data confirmed the economic burden of RV GE episodes. In conclusion, RV GE episodes are a health burden as well as an economic burden also for the children in a developed country such as Switzerlan

Family changes and residential mobility among immigrant and native-born populations: Evidence from Swiss administrative data

Background: Much of the literature on immigrant relocation has focused on human and social capital and has often ignored the role of life-course events as triggers of internal migration and residential mobility. We know that family transitions are closely tied to residential relocation, but the extent to which they might explain differential mobility patterns among immigrant and native-born populations is still largely unknown. Objective: Using Swiss administrative registers and a nationally representative survey, we apply discrete-time logistic models to assess whether residential mobility responses to family changes differ between immigrant and native-born populations. We highlight various patterns of housing adjustment at times of childbirth, marriage (among cohabiting and non-cohabiting partners), and divorce. We also investigate the factors accounting for the differences between foreign- and native-born groups. Contribution: The results suggest that residential mobility increases at times of childbirth, marriage, and divorce for both native- and foreign-born populations living in Switzerland. The results also suggest that the timing and intensity of residential changes in response to (or in anticipation of) family transitions differ across groups according to their birthplace. Compared to native-born residents, immigrants prove to be more residentially mobile at the time of marriage, owing to specific pre-marital cohabitation behaviours, but less residentially mobile at the time of childbirth, an event inherently linked to housing improvement. Household income was identified as an important mitigating factor within the joint processes of family changes and residential mobility. We argue that linking residential mobility to life-course events and statuses can serve as an alternative, dynamic marker of residential integration, preferences, and housing disadvantage among immigrant population