TBT pollution in Tunisian coastal lagoons as indicated by imposex in Hexaplex trunculus (Gastropoda: Muricidae)

1 - Most of the shipping traffic in Tunisia comes from foreign countries that already enforced tributyltin (TBT) regulation.2 - Local and imported antifouling paints in Tunisia did not contain TBT.3 - Actual TBT contamination in Tunisia is the result of an old/historical pollution events.4 - Here we report data on imposex in Hexaplex trunculus from three Tunisian lagoons. This gastropod, which locally has fishery great commercial value, is currently used mostly for monitoring TBT effects in transitional and marine waters in the Mediterranean Sea.5 - Our results showed a decrease of imposex in Bizerta and in Northern Tunis lagoons, whilst in the southernmost lagoon of Boughrara imposex has significantly increased.6 - The effect of specimen size and reproductive activity on penis length variation in males and on the relative penis length index was validated.7 - Overall, we found that TBT is still a significant pollutant in the Tunisian waters, which requires further studies on the contamination causes

Identification of differential gene expression in in vitro FSH treated pig granulosa cells using suppression subtractive hybridization

FSH, which binds to specific receptors on granulosa cells in mammals, plays a key role in folliculogenesis. Its biological activity involves stimulation of intercellular communication and upregulation of steroidogenesis, but the entire spectrum of the genes regulated by FSH has yet to be fully characterized. In order to find new regulated transcripts, however rare, we have used a Suppression Subtractive Hybridization approach (SSH) on pig granulosa cells in primary culture treated or not with FSH. Two SSH libraries were generated and 76 clones were sequenced after selection by differential screening. Sixty four different sequences were identified, including 3 novel sequences. Experiments demonstrated the presence of 25 regulated transcripts. A gene ontology analysis of these 25 genes revealed (1) catalytic; (2) transport; (3) signal transducer; (4) binding; (5) anti-oxidant and (6) structural activities. These findings may deepen our understanding of FSH's effects. Particularly, they suggest that FSH is involved in the modulation of peroxidase activity and remodelling of chromatin

Genome-wide linkage analysis of inguinal hernia in pigs using affected sib pairs

BACKGROUND: Inguinal and scrotal hernias are of great concern to pig producers, and lead to poor animal welfare and severe economic loss. Selection against these conditions is highly preferable, but at this time no gene, Quantitative Trait Loci (QTL), or mode of inheritance has been identified in pigs or in any other species. Therefore, a complete genome scan was performed in order to identify genomic regions affecting inguinal and scrotal hernias in pigs. Records from seedstock breeding farms were collected. No clinical examinations were executed on the pigs and there was therefore no distinction between inguinal and scrotal hernias. The genome scan utilised affected sib pairs (ASP), and the data was analysed using both an ASP test based on Non-parametric Linkage (NPL) analysis, and a Transmission Disequilibrium Test (TDT). RESULTS: Significant QTLs (p < 0.01) were detected on 8 out of 19 porcine chromosomes. The most promising QTLs, however, were detected in SSC1, SSC2, SSC5, SSC6, SSC15, SSC17 and SSCX; all of these regions showed either statistical significance with both statistical methods, or convincing significance with one of the methods. Haplotypes from these suggestive QTL regions were constructed and analysed with TDT. Of these, six different haplotypes were found to be differently transmitted (p < 0.01) to healthy and affected pigs. The most interesting result was one haplotype on SSC5 that was found to be transmitted to hernia pigs with four times higher frequency than to healthy pigs (p < 0.00005). CONCLUSION: For the first time in any species, a genome scan has revealed suggestive QTLs for inguinal and scrotal hernias. While this study permitted the detection of chromosomal regions only, it is interesting to note that several promising candidate genes, including INSL3, MIS, and CGRP, are located within the highly significant QTL regions. Further studies are required in order to narrow down the suggestive QTL regions, investigate the candidate genes, and to confirm the suggestive QTLs in other populations. The haplotype associated with inguinal and scrotal hernias may help in achieving selection against the disorder

SiC-VJFETs power switching devices: an improved model and parameter optimization technique

Silicon carbide junction field effect transistor (SiC-JFETs) is a mature power switch newly applied in several industrial applications. SiC-JFETs are often simulated by Spice model in order to predict their electrical behaviour. Although such a model provides sufficient accuracy for some applications, this paper shows that it presents serious shortcomings in terms of the neglect of the body diode model, among many others in circuit model topology. Simulation correction is then mandatory and a new model should be proposed. Moreover, this paper gives an enhanced model based on experimental dc and ac data. New devices are added to the conventional circuit model giving accurate static and dynamic behaviour, an effect not accounted in the Spice model. The improved model is implemented into VHDL-AMS language and steady-state dynamic and transient responses are simulated for many SiC-VJFETs samples. Very simple and reliable optimization algorithm based on the optimization of a cost function is proposed to extract the JFET model parameters. The obtained parameters are verified by comparing errors between simulations results and experimental data

Modelling, analysis, and experimental study of SiC JFET body diode

Within Silicon Carbide Junction Field Effect Transistor (SiC-JFET) model, body diode is not extensively studied and almost under-researched. Body diode remains a complex device to study particularly during switching transients. In this paper, the JFET body diode is experimentally demonstrated to be a power PiN diode. Finite element method model based on the device geometry and SiC material is used to accurately simulate this diode. Accurate simulations are necessary for analysis and verification purposes. Simulation relies on component models and associated parameters. The paper focuses on a step-by-step extraction procedure for design parameters of the SiC-JFET body diode. A comparative study between experimental data and simulation results is given to validate the device model and associate parameters

Role of dispersant and humidity on the setting of millimetric films of aluminous cement prepared by tape casting

An aluminous cement (Secar 71 from Lafarge) has been used for preparing millimetre thick films by tape casting. Slurry preparation is described. The effect of several dispersants has been studied. The optimum dispersion, associated with the minimum viscosity, is obtained with minimal amounts of dispersant in the case of acetic and propionic acids. Indeed, the corresponding quantities of dispersant are less than 0.5% by weight relative to cement. In addition to its dispersive role, acetic acid plays a role in the setting. It has a retarding effect below 1% by weight relative to the mass of cement and from this amount, it plays an accelerating role on setting. Tapes prepared with cement, water, acetic acid, PEG 300 have been left to set in different environments at 20 ◦C (50% or 95% relative humidity, water). The formation of aluminous calcium hydrates is most important when setting is done in water. Lastly, the advantage of setting in water is also discussed with respect to the elimination of the different organic products that have been used for tape casting

Calcium aluminate cement tapes - Part I: Structural and microstructural characterizations

International audienceThis present paper concerns the structural and microstructural characterization of 1 mm thick calcium aluminate cement tapes prepared by tape casting. A study of the effect of environment, time and the consolidation temperature on the structural properties and microstructure has been undertaken. Consolidation environments studied are air, water and an environment saturated in humidity for storage durations of 1, 4 or 30 days at a temperature of 20 or 70 °C. The structural characterization was carried out using XRD. The microstructural characterization was carried out through the distribution of pore volume by mercury porosimetry measurements and SEM micrographs. The effects of the various consolidation parameters were compared and discussed. The tape consolidated for 30 days in water at 70 °C has the most advanced hydration with the formation of stable hydrates. This is evidenced by the reduction of the inter-granular pore size and the microstructure densification

Calcium aluminate cement tapes - Part II: Physical properties

International audienceTape casting is a process often used for the preparation of microelectronics substrates. The present work is a continuation of the first part where we have discussed the structural and microstructural characteristics of calcium aluminate cement tape. Indeed, in this second part, we focus on the physical properties of these tapes such as electrical, thermal, mechanical characterizations and surface roughness. We studied in particular how these physical properties vary according to the setting environment (water, air at 50% relative humidity or air saturated in humidity), setting time (1 day, 4 days or 1 month) and setting temperature (20 °C or 70 °C in the case of water setting environment). A Heat treatment on the consolidated tape was made essentially to decrease the dielectric constant. Following our results and comparing the physical properties with those of substrates commonly used in microelectronics, in particular alumina substrates, our films can be potentially used as microelectronics substrate