Performances des Ciments Sur-Sulfatés

29ème rencontre de l’AUGC Tlemcen (29-31 Mai 2011).Les ciments sur-sulfatés (CSS), sacrifiés sur l’autel de la productivité, pourraient constituer une alternative au ciment Portland ordinaire, tant du point de vue de l’impact CO2 que de la réalisation de mortiers et bétons à bas pH. Le renouveau des ciments sur-sulfatés passe donc par une confrontation au contexte normatif nouvellement entré en vigueur. Dans ce papier, nous présentons les premiers résultats obtenus au laboratoire sur l’optimisation des compositions et des conditions de cure de tels ciments

RILEM Interlaboratory Test on Interlayer Bonding of Asphalt Pavements

The RILEM TG 4 organized an interlaboratory test in order to compare the different test procedures to assess the interlayer bonding properties of asphalt pavement. The pavement was composed of two layers. Three different interface conditions were chosen. The first pavement was laid without interface treatment and the others with two different types of emulsion. 14 laboratories from 11 countries participated in this study and carried out shear or torque tests on 1400 cores. The maximum shear or torque load and the corresponding displacement were measured and the shear or torque stress was calculated as a function of the following parameters: diameter, test temperature, test speed, stress applied normal to the interface and age of the specimen. This paper presents the results of this study in terms of precision and correlations regarding the parameter

Study of genetic damage in the japanese oyster induced by an environmentally-relevant exposure to diuron: evidence of vertical transmission of dna damage

Pesticides represent a major proportion of the chemical pollutants detected in French coastal waters and hence a significant environmental risk with regards to marine organisms. Commercially-raised bivalves are particularly exposed to pollutants, among them pesticides, as shellfish farming zones are subject to considerable pressure from agricultural activities on the mainland. The aims of this study were to determine (1) the genotoxic effects of diuron exposure on oyster genitors and (2) the possible transmission of damaged DNA to offspring and its repercussions on oyster fitness. To investigate these points, oysters were exposed to concentrations of diuron close to those detected in the Marennes-Oleron Basin (two 7-day exposure pulses at 0.4 and 0.6 μg L−1) during the gametogenesis period. Genomic abnormalities were characterized using two complementary approaches. The Comet assay was applied for the measurement of early and reversible primary DNA damage, whereas flow cytometry was used to assess the clastogenic and aneugenic effect of diuron exposure. Polar Organic Chemical Integrative Samplers (POCIS) were used in exposed and assay tanks to confirm the waterborne concentration of diuron reached during the experiment. The results obtained by the Comet assay clearly showed a higher level of DNA strand breaks in both the hemocytes and spermatozoa of diuron-exposed genitors. The transmission of damaged genetic material to gamete cells could be responsible for the genetic damage measured in offspring. Indeed, flow cytometry analyses showed the presence of DNA breakage and a significant decrease in DNA content in spat from diuron-exposed genitors. The transmission of DNA damage to the offspring could be involved in the negative effects observed on offspring development (decrease in hatching rate, higher level of larval abnormalities, delay in metamorphosis) and growth. In this study, the vertical transmission of DNA damage was so highlighted by subjecting oyster genitors to short exposures to diuron at medium environmental concentrations. The analysis of POCIS showed that oysters were exposed to integrated concentrations as low as 0.2 and 0.3 μg L−1, emphasing the relevance of the results obtained and the risk associated to chemical contamination for oyster recruitment and fitness

Isolation and characterization of Psalmopeotoxin I and II: two novel antimalarial peptides from the venom of the tarantula Psalmopoeus cambridgei

AbstractTwo novel peptides that inhibit the intra-erythrocyte stage of Plasmodium falciparum in vitro were identified in the venom of the Trinidad chevron tarantula, Psalmopoeus cambridgei. Psalmopeotoxin I (PcFK1) is a 33-residue peptide and Psalmopeotoxin II (PcFK2) has 28-amino acid residues; both have three disulfide bridges and belong to the Inhibitor Cystine Knot superfamily. The cDNAs encoding both peptides were cloned, and nucleotide sequence analysis showed that the peptides are synthesized with typical signal peptides and pro-sequences that are cleaved at a basic doublet before secretion of the mature peptides. The IC5O of PcFK1 for inhibiting P. falciparum growth was 1.59±1.15 μM and that of PcFK2 was 1.15±0.95 μM. PcFK1 was adsorbed strongly to uninfected erythrocytes, but PcFK2 was not. Neither peptide has significant hemolytic activity at 10 μM. Electrophysiological recordings in isolated frog and mouse neuromuscular preparations revealed that the peptides (at up to 9.3 μM) do not affect neuromuscular transmission or quantal transmitter release. PcFK1 and PcFK2 do not affect the growth or viability of human epithelial cells, nor do they have any antifungal or antibacterial activity at 20 μM. Thus, PcFK1 and PcFK2 seem to interact specifically with infected erythrocytes. They could therefore be promising tools for antimalaria research and be the basis for the rational development of antimalarial drugs

Design, recruitment, logistics, and data management of the GEHA (Genetics of Healthy Ageing) project

In 2004, the integrated European project GEHA (Genetics of Healthy Ageing) was initiated with the aim of identifying genes involved in healthy ageing and longevity. The first step in the project was the recruitment of more than 2500 pairs of siblings aged 90 years or more together with one younger control person from 15 areas in 11 European countries through a coordinated and standardised effort. A biological sample, preferably a blood sample, was collected from each participant, and basic physical and cognitive measures were obtained together with information about health, life style, and family composition. From 2004 to 2008 a total of 2535 families comprising 5319 nonagenarian siblings were identified and included in the project. In addition, 2548 younger control persons aged 50-75 years were recruited. A total of 2249 complete trios with blood samples from at least two old siblings and the younger control were formed and are available for genetic analyses (e.g. linkage studies and genome-wide association studies). Mortality follow-up improves the possibility of identifying families with the most extreme longevity phenotypes. With a mean follow-up time of 3.7 years the number of families with all participating siblings aged 95 years or more has increased by a factor of 5 to 750 families compared to when interviews were conducted. Thus, the GEHA project represents a unique source in the search for genes related to healthy ageing and longevity