Recherches sur les risques pouvant resulter de la pollution chimique des eaux d'alimentation—I. Etude de la toxicite a long terme chez le rat et la souris des micropolluants organiques chloroformo-extractibles a partir d'eaux livrees a la consommation humaine

Groups of 50 weaning mice and 50 weaning rats of both sexes received organic micropollutants (extracted from drinking water by chloroform at neutral pH) in their diet for their whole life span. The doses were calculated from a 31 water daily intake by a man of 60 kg, with application of safety factors of 100 and 200. Long term toxicity studies showed:

1. 1. Biochemical changes: increase of transaminases and ornithine carbamyl-transferase activities in blood serum, which, taking into account the variation of activities of the same enzymes in liver parenchyma do not appear to be caused only by hepatic cytolysis.

2. 2. Histopathological changes: (a) liver enlargement, cellular hypertrophy of the liver, steatosis and cirrhosis; (b) significant increase of the incidence of malignant tumours in female mice and in male and female rats with, in the latter, a dose response relationship.

3. 3. Significant increase in mortality rates, in both species, beginning much earlier in males than in females.

A critical discussion is given of results in relation to their value as alarm signs regarding prediction of eventual manifestation of such toxic potentialities in man from consumption, of drinking water containing organic micropollutants.

Résumé

Des micropolluants organiques, obtenus par extraction au chloroforme à pH neutre à partir d'une eau offerte à la consommation humaine (obtenue par traitements classiques, comportant une préchloration, une ozonation et une post-chloration terminale, d'une eau brute de riviére), ont été administrés, ˜a partir du sevrage, après incorporation au régime, á des lots de 50 rats et de 50 souris, par moitié mâles et femelles. Les doses ont été calculées à partir de la consommation quotidienne moyenne de 31 d'eau pour un homme de 60 kg, avec application de facteurs de sécurité de 100 et 200.Les résultats obtenus mettent en evidence les faits principaux suivants:

1. 1. Sur le plan biochimique: Augmentation des activités des transaminases et de l'ornithine transférase au niveau du sérum sanguin traduisant une atteinte du foie qui, d'aprés les observations relatives á l'évolution des taux des mêmes enzymes au niveau du parenchyme hépatique, ne parait pas pouvoir être rapportée à une simple action cytolytique.

2. 2. Sur le plan histologique: (a) phénoménes d'hypertrophie cellulaire au niveau du tissu hépatique avec tendance à la dégénérescence graisseuse et lésions de type cirrhotique; (b) augmentation significative du nombre des tumeurs chez les souris femelles et chez rats des deux sexes avec, au moins chez cette derniére espéce, une corrélation avec la dose.

3. 3. Parallélement, accroissement significatif du taux de mortalité chez les deux espéces, augmentation débutant beaucoup plus précocément chez les mâles.

Discussion critique des résultats obtenus en ce qui concerne notamment leur valeur comme signes d'alarme quant à la manifestation éventuelle de potentialités toxiques pouvant résulter, chez l'homme, de l'ingestion prolongée d'eaux d'alimentation renfermant des traces de micropolluants.     

Fringe field switching of a twisted nematic liquid crystal device for a single-cell-gap transflective display

We propose an optical configuration of a twisted nematic liquid crystal device driven by a fringe field for a single-cell-gap transflective display. The dark state of the reflective part is realized by a nematic liquid crystal layer with a twist angle of 63.6 degrees and retardation of 194 nm, while a quarter-wave plate is inserted for the dark state of the transmissive part. Wavelength dispersion of the liquid crystal layer is suppressed by introducing a half-wave plate. Different directions of electric fields rotate liquid crystals to 15 degrees for the bright state of the reflective part, but to -30 degrees for that of the transmissive part. With the proposed configuration, we can realize a high-brightness single-gamma transflective display in a single-cell-gap structure without any in-cell retardation layers.     

CMOS level shifters from 0 to 18 V output

A design methodology for level shifters voltage translators, where the output voltage ranges from 0 to 18 V, and the input voltage ranges from 2 to 5.5 V in a 0.6 µm CMOS-HV technology, is presented. This family of circuits have a special interest in the case of implantable medical devices where is common to handle previously unknown voltages either positive or negative, above or below the control logic supply V_DD. Two application examples are presented: a composite switch to control negative stimuli voltage pulses, and a multi-channel programmable charge-pump voltage multiplier, aimed at charging the output capacitors of an IMD.

     

A current-reuse biomedical amplifier with a NEF < 1

Digital image authenticity is always an imperative question to tackle whenever a digital image is being assessed for its content. Using digital forensic algorithms, the image will be evaluated for various traces left from numerous categories of manipulations including, among others, copy–move operations. Later this is considered an essential block in most digital image forgeries. It results in changing the information incorporated in a scene, hiding information from an image, or emphasizing some parts of the image. In this paper we propose and investigate two main approaches that differ in the feature extraction process in order to detect copy–move traces. In the first method, we use two-dimensional discrete cosine transform. Whereas in the second method, the phase response of Gabor filter is being used. Instead of being applied on the image directly, the two methods are applied over the first, the second or the third principal component of the image after being divided into overlapping blocks. Combining these conditions results in six basic implementations that are investigated under three parameters that must be optimized: block dimension, contrast and similarity thresholds. Results from testing and validation process demonstrate that the highest performance, in terms of false accept rate, is obtained when using Gabor filter associated with the first principal component of the image outperforming a reference method we implemented as well.     

Thermally conductive polyamide 6/carbon filler composites based on a hybrid filler system

We explored the use of a hybrid filler consisting of graphite nanoplatelets (GNPs) and single walled carbon nanotubes (SWCNTs) in a polyamide 6 (PA 6) matrix. The composites containing PA 6, powdered GNP, and SWCNT were melt-processed and the effect of filler content in the single filler and hybrid filler systems on the thermal conductivity of the composites was examined. The thermal diffusivities of the composites were measured by the standard laser flash method. Composites containing the hybrid filler system showed enhanced thermal conductivity with values as high as 8.8 W (m · K)⁻¹, which is a 35-fold increase compared to the thermal conductivity of pure PA 6. Thermographic images of heat conduction and heat release behaviors were consistent with the thermal conductivity results, and showed rapid temperature jumps and drops, respectively, for the composites. A composite model based on the Lewis–Nielsen theory was developed to treat GNP and SWCNT as two separate types of fillers. Two approaches, the additive and multiplicative approaches, give rather good quantitative agreement between the predicted values of thermal conductivity and those measured experimentally.     

Crosslinked monosulfonated poly(arylene ether) using cyclodimerization of trifluorovinyl ether groups for fuel cell applications

A crosslinker and crosslinkable sulfonated poly(arylene ether)s with trifluorovinyl ether groups were synthesized via reaction of 4‐trifluorovinyloxyphenol for application in fuel cells. Crosslinked poly(arylene ether) membranes were prepared by thermal irradiation, and the cyclodimerization of the trifluorovinyl ether groups in the polymers as well as the crosslinker was confirmed using differential scanning calorimetry and infrared measurements. These crosslinked membranes showed a low swelling ratio, comparable to that of Nafion 112. The proton conductivity of the crosslinked membranes was 0.17 and 0.3 S cm^?1 at 30 and 80 °C, respectively, much higher than that of Nafion 112 under the same conditions. The excellent dimensional stability and high conductivity of the crosslinked membranes can be attributed to this new type of crosslinking system (end‐group crosslinking) as well as the chemical structure of crosslinked (multi‐block) polymers. Copyright © 2011 Society of Chemical Industry     

Dispersion polymerization in supercritical carbon dioxide using comb-like fluorinated polymer surfactants having different backbone structures

Comb-like fluorinated polymers with different backbone structures, poly(heptadecafluorodecyl acrylate) (PA-R_f), poly[oxy[(2-perfluorooctylethylene)thiomethyl]ethylene] (PEO-R_f), and poly[p-[[(perfluorooctylethylene)thio]methyl]styrene] (PS-R_f), were used as surfactants in dispersion polymerization to examine the effect of backbone structure on the formation of polymer particles. Dispersion polymerization of monomers with different polarities using these comb-like fluorinated polymer surfactants in CO₂ showed that PEO-R_f containing a polar oxyethylene backbone was an effective surfactant for the dispersion polymerization of a polar monomer, such as N-vinyl-2-pyrrolidone, whereas PA-R_f was effective for less polar monomers, such as methyl methacrylate and N-vinyl caprolactam.