Potential influence of microorganisms on the corrosion of carbon steel in the French high- and intermediate-level long-lived radioactive waste disposal context

In the context of the high-level radioactive waste disposal CIGEO, the corrosion rate due to microbially influenced corrosion (MIC) has to be evaluated. In France, it is envisaged to dispose of high- and intermediate-level long-lived radioactive waste at a depth of 500 m in a deep geological disposal, drilled in the Callovo-Oxfordian claystone (Cox) formation. To do so, a carbon steel casing will be inserted inside disposal cells, which are horizontal tunnels drilled in the Cox. A specific cement grout will be injected between the carbon steel casing and the claystone. A study was conducted to evaluate the possibility of MIC on carbon steel in the foreseeable high radioactive waste disposal. The corrosiveness of various environments was investigated at 50°C and 80°C with or without microorganisms enriched from samples of Andra's underground research laboratory. The monitoring of corrosion during the experiments was ensured using gravimetric method and real-time corrosion monitoring using sensors based on the measurements of the electrical resistance. The corrosion data were completed with microbiological analyses including cultural and molecular characterizations.     

Highly integrated direct conversion receiver for GSM/GPRS/EDGE with on-chip 84-dB dynamic range continuous-time /spl Sigma//spl Delta/ ADC

This paper describes a highly digitized direct conversion receiver of a single-chip quadruple-band RF transceiver that meets GSM/GPRS and EDGE requirements. The chip uses an advanced 0.25-/spl mu/m BiCMOS technology. The I and Q on-chip fifth-order single-bit continuous-time sigma-delta (/spl Sigma//spl Delta/) ADC has 84-dB dynamic range over a total bandwidth of /spl plusmn/135 kHz for an active area of 0.4 mm/sup 2/. Hence, most of the channel filtering is realized in a CMOS IC where digital processing is achieved at a lower cost. The systematic analysis of dc offset at each stage of the design enables to perform the dc offset cancellation loop in the digital domain as well. The receiver operates at 2.7 V with a current consumption of 75 mA. A first-order substrate coupling analysis enables to optimize the floor plan strategy. As a result, the receiver has an area of 1.8 mm/sup 2/.     

Expression of horse and donkey LH in COS-7 cells: evidence for low FSH activity in donkey LH compared with horse LH

Horse (Equus caballus) luteinizing hormone (eLH) and chorionic gonadotrophin (eCG), which have the same amino acid sequence, are unusual in that, although they express only LH activity in equids, they express dual LH and FSH activities in all other species tested. Donkey (Equus asinus) LH (dkLH) and CG (dkCG), which also share an identical peptide backbone, have been less well characterized and conflicting results concerning their FSH activity in heterologous species have appeared in the literature. In order to assess and compare the intrinsic LH and FSH activities of the horse and donkey LHs in heterologous species, recombinant eLH (r.eLH/CG) and recombinant dkLH (r.dkLH/CG) were expressed, for the first time, in COS-7 cells. Their LH activities were assessed in a rat Leydig cell bioassay, and their FSH activities were estimated in a bioassay using Y1 cells stably expressing the human FSH receptor. Human CG (hCG) was expressed (r.hCG) and analysed in the same system. The results showed that, whereas r.dkLH/CG was about twice as active as r.eLH/CG in the LH bioassay, it was five times less active than r.eLH/CG in the FSH bioassay; r.hCG was about three times less active than r.eLH/CG in the LH bioassay but was completely inactive in the FSH bioassay. These results confirm that dkLH/CG possesses significant FSH activity in heterologous species that is not attributable to contamination with FSH.     

Evidence for the presence of pro-oxytocin/neurophysin-converting enzyme in the human ovary

The activity of pro-oxytocin/neurophysin (pro-OT/Np)-processing enzymes was determined in human granulosa cells, follicular fluids and purified secretory granules of corpora lutea. We detected the presence of an endoprotease which releases OT-Gly10-Lys11-Arg12 on cleavage of the synthetic pro-OT/Np(1-20) peptide after the dibasic Lys11-Arg12 doublet. This endoprotease was inhibited by EDTA, but was not affected by phenylmethanesulfonyl fluoride and pepstatin. Enzymatic activity was markedly reduced by replacement of L-Arg by D-Arg in the basic amino acid doublet of the substrate. The molecular weight of this enzyme was estimated to be 60 kDa. These features closely resembled those of the endoprotease identified in the bovine pituitary. The endoprotease is a metalloenzyme, specific for the Lys-Arg doublet. We also detected a carboxypeptidasic activity, inhibited by guanidinoethane-mercaptosuccinic acid. In the light of our previous detection of the processing intermediates, OT-Gly-Lys-Arg, OT-Gly-Lys and OT-Gly, in human ovary, these observations are in favour of a pro-OT/Np-processing pathway in the human ovary comparable with that in the bovine ovary. Moreover, these results confirm that oxytocin post-translational processing occurs in the human ovary and strongly suggest that pro-OT/Np is synthesized locally.     

Catalytic wall reactor: Catalytic coatings of stainless steel by VOx/TiO2 and Co/SiO2 catalysts

Catalytic wall (structured) reactors and structured supports are suitable to study the catalytic properties of nanosized materials. The coating of metallic (aluminum and stainless steel) plates by thin layers of active phase is presented in two cases, VO_x/TiO₂ and Co/SiO₂, catalysts used in the oxidative dehydrogenation (ODH) of propane and in Fischer–Tropsch synthesis (FTS) of clean fuels, respectively. The preparation of coated plates and their characterisation by various methods of physicochemical analysis are described. Both chemical and physical methods were used for coating. VO_x/TiO₂ layers were obtained by grafting of Ti (on Al or stainless-steel plates) and V (on TiO₂) alkoxides and use of sol–gel media or suspension. A silica primer was deposited (on stainless-steel plate) by plasma-assisted chemical vapour deposition (PACVD) onto which Co oxide and silica were coprecipitated from sol–gel. The catalytic experiments in the respective reactions were carried out in special plate reactors and compared with those of catalytic powders. The study shows that the coating of a metallic substrate by a catalyst is not straightforward and requires specific studies dealing with both chemistry (chemical affinity between substrate and catalytic layers) and catalytic engineering (catalytic performance in taylor-made reactors).     

Using vanishing points for camera calibration and coarse 3D reconstruction from a single image

In this paper, we show how to calibrate a camera and to recover the geometry and the photometry (textures) of objects from a single image. The aim of this work is to make it possible walkthrough and augment reality in a 3D model reconstructed from a single image. The calibration step does not need any calibration target and makes only four assumptions: (1) the single image contains at least two vanishing points, (2) the length (in 3D space) of one line segment (for determining the translation vector) in the image is known, (3) the principle point is the center of the image, and (4) the aspect ratio is fixed by the user. Each vanishing point is determined from a set of parallel lines. These vanishing points help determine a 3D world coordinate system R _o. After having computed the focal length, the rotation matrix and the translation vector are evaluated in turn for describing the rigid motion between R _o and the camera coordinate system R _c. Next, the reconstruction step consists in placing, rotating, scaling, and translating a rectangular 3D box that must fit at best with the potential objects within the scene as seen through the single image. With each face of a rectangular box, a texture that may contain holes due to invisible parts of certain objects is assigned. We show how the textures are extracted and how these holes are located and filled. Our method has been applied to various real images (pictures scanned from books, photographs) and synthetic images.     

Fast multi-scale detection of overlapping communities using local criteria

Many systems can be described using graphs, or networks. Detecting communities in these networks can provide information about the underlying structure and functioning of the original systems. Yet this detection is a complex task and a large amount of work was dedicated to it in the past decade. One important feature is that communities can be found at several scales, or levels of resolution, indicating several levels of organisation. Therefore a graph may have several community structures. Also networks tend to be large and hence require efficient processing. In this work, we present a new algorithm with linear complexity for the fast detection of communities across scales using a local criterion. We exploit the local aspect of the criterion to enable parallel computation and improve the execution speed further. The algorithm is tested against very large generated multi-scale networks and experiments demonstrate its efficiency and accuracy.     

A weighted mean excess function approach to the estimation of Weibull-type tails

A new class of estimators for the Weibull-tail coefficient is proposed. The estimators are based on linear combinations of log-spacings of the mean excess function evaluated at high levels. The asymptotic distribution of this new class of estimators is derived under some mild conditions on the weight function and a second order condition on the tail behavior. The finite sample properties of some estimators obtained with important special cases of the weight function are examined with a small simulation experiment.