Epidemic typhus imported from Algeria.

We report epidemic typhus in a French patient returning from Algeria. The diagnosis was confirmed by serologic testing and the isolation of Rickettsia prowazekii in blood. Initially the patient was thought to have typhoid fever. Because body lice are prevalent in industrialized regions, the introduction of typhus to pediculosis-endemic areas poses a serious public health risk

Participation des radicaux carbonate à l’oxydation de l’atrazine lors de l’ozonation de solutions aqueuses contenant des ions hydrogénocarbonate

L’étude porte sur la détermination de la contribution des espèces O3, OH° et CO3°- dans la dégradation de l’atrazine lors de l’ozonation de solutions contenant différentes concentrations en ions hydrogénocarbonate et en carbone organique. Le suivi de la concentration en atrazine et en ozone dissous, et les expressions cinétiques ont permis de calculer les concentrations en radicaux hydroxyle et carbonate au cours des réactions. A partir des données expérimentales obtenues sur des eaux pures additionnées de carbone organique et inorganique, les résultats indiquent que l’élimination du micropolluant résulte de l’action de l’ozone (pour une faible part), des radicaux hydroxyle issus de la décomposition de l’ozone, mais aussi pour une part très significative, des radicaux carbonate. La participation des radicaux CO3°- diminue lorsque la concentration en carbone organique augmente. Les radicaux carbonate peuvent être responsable de plus de 40 % de la dégradation de l’atrazine lors de l’ozonation en présence de 7 mM d’ions hydrogénocarbonate et 129 µM d’ions glycolate utilisés comme molécule modèle pour l’apport de carbone organique. Les résultats obtenus sur des eaux naturelles confirment les conclusions déduites des expériences sur des eaux de composition connue.The inhibiting effect of bicarbonate ions on the oxidation of organic molecules by the hydroxyl radicals is well known. However, the carbonate radicals resulting from the consumption of the OH° radicals by these ions have only rarely been considered to participate in the reactions of organic pollutant removal. In this study, the contribution of O3, OH° and CO3°- radicals in the degradation of atrazine during ozonation of aqueous solutions containing various concentrations of bicarbonate ions and organic carbon, was determined.Experiments were performed in a bubble column fed continuously by ozone gas and an aqueous solution containing atrazine (0.05 µM) as the model molecule. Three sets of experiments were carried out at pH 8:1. pure water with different concentrations of bicarbonate ions (0.35-70 mM);2. pure water with different concentrations of bicarbonate ions (0.35 and 7 mM) and glycolate ions (0-129 µM) selected as the organic carbon source;3. surface and tap waters.For different contact times in the ozonation reactor, the concentrations of atrazine and dissolved ozone were determined. Inputting these data into kinetic equations enabled us to calculate the concentrations of hydroxyl and carbonate radicals during ozonation. In the absence of organic carbon, the concentration of hydroxyl radicals was determined by assuming steady state conditions (equation II). The concentration of carbonate radicals was deduced from the slope of the evolution of atrazine concentration ([A]0 -[A])/[A] versus the contact time, and the values of ozone and OH° radical concentration (equation IV). In the presence of organic matter, the concentration of OH° radicals was calculated from the evolution of ([A]0 -[A])/[A] versus the contact time, and by replacing the carbonate radical concentration by the expression involving the OH° radicals (equations VI-IX). From the steady state assumption, the concentration of carbonate radicals followed the hydroxyl radical evolution.In the absence of organic carbon, the results confirmed the global inhibiting effect of bicarbonate ions on the removal of atrazine molecules. However, the concentrations of the carbonate radicals were much higher than the OH° radical concentrations (above 4x10-10 M compared to 2x10-12 M, respectively). The concentration of these latter radicals decreased as the concentration of bicarbonate ions increased. Under these conditions, the carbonate radicals were mainly responsible for the removal of atrazine.From the experiments in pure water with given concentrations of bicarbonate and glycolate ions, the hydroxyl radical concentration increased with the concentration of glycolate ions, thus confirming the promoter property of this organic molecule, which favours the removal of atrazine. However, in most cases, the presence of organic carbon was found to be unfavourable to the concentration of carbonate radicals. Therefore, the participation of the carbonate radicals decreased with increasing organic carbon content. Nevertheless, their contribution to atrazine degradation can reach more than 40% during ozonation in the presence of bicarbonate ions (7 mM) and glycolate ions (129 µM) used as an organic carbon source.The results obtained from the experiments carried out in natural waters agree with the main conclusions from the above experiments. The removal of atrazine involved ozone, hydroxyl radicals as well as carbonate radicals. The contribution of carbonate radicals decreased when the ratio of inorganic carbon to organic carbon decreased. In the surface and tap waters tested, this contribution was found to be 10 to 40 % and 43 % respectively

La pêche artisanale au Sénégal : qualité de la matière première destinée aux entreprises exportatrices

Les conditions d’hygiène de la pêche artisanale au Sénégal ne respectent pas toujours les normes de qualité requises. Ce présent travail se propose d’étudier la qualité de trois espèces de poissons démersaux ; la sole limande (Syacium guineensis), le mérou à points bleus (Cephalopholis taeniops) et le rouget (Pseudupeneus prayensis) débarqués par la pêche artisanale. Ces espèces sont suivies depuis la capture jusqu’à leur acheminement en usine. L’évaluation sensorielle de la fraîcheur du poisson a consisté à tester la qualité par le toucher, l’odorat, la vue et le goût. Le dosage de l’azote basique volatil total (ABVT) a permis de déterminer la teneur totale en azote des bases azotées volatiles résultant de la dégradation des composés azotés du poisson lors de l’altération. La méthode d’analyse microbiologique utilisée est celle qui consiste à incorporer un volume donné de la prise d’essai et de ses dilutions dans un milieu de culture solide. A l’analyse sensorielle, les trois espèces, aux différentes étapes, étaient de très bonne qualité. Les valeurs de la flore mésophile aérobie sur le poisson à la capture sont très faibles contrairement au débarquement et à l’entrée en usine. Au niveau des branchies et de la peau, les résultats montrent une augmentation significative de la flore au débarquement et à l’entrée en usine. Au niveau des viscères, la flore augmente jusqu’au débarquement puis décroît. Les résultats des analyses chimiques ne reflètent pas forcément les risques de dégradation du poisson.Mots-clés : pêche artisanale, poisson, qualité matière première, exportation, Sénégal.Artisanal fisheries in Senegal: Quality of raw materials for exporting companiesHygienic conditions of artisanal fisheries in Senegal do not always respect the required quality standards. This study expects to scrutinize the quality of bottom fish sole (Syacium guineensis), grouper blue spotted (Cephalopholis taeniops), red mullet (Pseudupeneus prayensis) disembarked by artisanal fisheries. These species are followed since the capture until their routing in factory. The sensory evaluation of fish freshness was to test the quality through touch, smell, sight and taste. The determination of total volatile basic nitrogen (ABVT) allowed determining the total nitrogen content of volatile nitrogenous bases resulting from the degradation of nitrogenous compounds in fish spoilage. The used-microbiological-method is the one that consist in incorporating a given volume of the sample and its dilutions in a solid cultural medium. The results of sensory analysis on the three species at different stopovers were very good. The values of the aerobic mesophilic flora on the fish caught are very low compared to the one landed at the entrance to the factory. At the gills and skin, the findings show a significant increase in flora and landed at the entrance to the factory. In the viscera, flora increases and then decreases until the debarkation. The results of sensory and chemical analysis may not reflect the risks of degradation of fish.Keywords : artisanal fisheries, fish, quality, raw materials, exportation, Senegal

Novel Tunnel-Contact-Controlled IGZO Thin-Film Transistors with High Tolerance to Geometrical Variability.

Thin insulating layers are used to modulate a depletion region at the source of a thin-film transistor. Bottom contact, staggered-electrode indium gallium zinc oxide transistors with a 3 nm Al2 O3 layer between the semiconductor and Ni source/drain contacts, show behaviors typical of source-gated transistors (SGTs): low saturation voltage (VD_SAT ≈ 3 V), change in VD_SAT with a gate voltage of only 0.12 V V-1 , and flat saturated output characteristics (small dependence of drain current on drain voltage). The transistors show high tolerance to geometry: the saturated current changes only 0.15× for 2-50 µm channels and 2× for 9-45 µm source-gate overlaps. A higher than expected (5×) increase in drain current for a 30 K change in temperature, similar to Schottky-contact SGTs, underlines a more complex device operation than previously theorized. Optimization for increasing intrinsic gain and reducing temperature effects is discussed. These devices complete the portfolio of contact-controlled transistors, comprising devices with Schottky contacts, bulk barrier, or heterojunctions, and now, tunneling insulating layers. The findings should also apply to nanowire transistors, leading to new low-power, robust design approaches as large-scale fabrication techniques with sub-nanometer control mature

High power passively mode-locked fiber laser based on graphene nanocoated optical taper

We experimentally demonstrate a passively mode-locked Er:Yb doped double-clad fiber laser usinga graphene nanocoated optical taper. Averaging 20lm of clad diameter with a length of 6 mm,such a saturable absorber enables a strong light–graphene interaction owing to the evanescent fieldof the excited cladding mode. With the highest pump power of 5 W, the 326th harmonic mode lock-ing of soliton bunches with an average output power of 520 mW was obtained in a fiber ring cavitythat has a fundamental frequency of 1.67 MHz. This is the highest average output power yetreported in graphene-based passively mode-locked fiber lasers

Laser à fibre dopée erbium à 1600 nm. Fonctionnement continu et verrouille en phase

L\u27objectif de cet article est de démontrer la possibilité de faire osciller à 1.6 µm un amplificateur à fibre double gaine dopée erbium opérant dans la bande C, en ajustant les pertes intra-cavité. Deux configurations de cavité ont été utilisées, une cavité en anneau et une cavité en forme de huit. Dans les deux cas, il est possible d\u27obtenir l\u27oscillation à 1.6 µm en continu ou bien en impulsions ultra-courtes

Kinetics of substrate oxidation and hydrogen peroxide production by Mycoplasma mycoides subsp. mycoides Large Colony (LC) type and Mycoplasma mycoides subsp. capri

Mycoplasma mycoides subsp. mycoides Large Colony (LC) type is a pathogen of goats causing contagious agalactia and respiratory disease, found on all continents where small ruminants are kept. It shares close genetic characteristics with M. mycoides subsp. capri. Substrate oxidation by 22 strains of M. mycoides subsp. mycoides LC from nine countries was compared with that of eight strains of M. mycoides subsp. capri from five countries. There was considerable similarity in the substrates used, but substrate saturation coefficients (Ks) varied for different substrates. Substrate utilization patterns and Ks values did not (1) significantly differentiate the LC strains from each other, (2) show any correlation with geographical origin, or (3) distinguish the LC strains from the capri strains. These results support previous studies justifying the reclassification of these subspecies as a single species

Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape

We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064 nm pulsed beams propagate from wider (122 µm) into smaller (37 µm) diameter. In the passive mode, increasing the input beam peak power above 20 kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600 nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length