Multi-Scale Numerical Viscoelastic Simulation of Fatigue Behavior of Asphalt Mixtures Modified with Polyphosphoric Acid

International audienc

Blood pressure and obesity in young adolescents in Tehran

Background: The objective of this study was to provide estimates of the prevalence of obesity among Iranian school children and to determine the association between obesity and blood pressure. Methods: During one school year (2003-2004), all children (n=2766) of the 5th stage of primary school studying in area 9 of Tehran school areas (divided by the Ministry of Education for management purposes) were screened for weight, height, and blood pressure. Findings: Of 2766 pupils, 1159 (41.9) were male and 1607 (58.1%) female. Mean weight of girls (37.1±8.3 kg) was significantly higher than that of boys (35.8±8.3 kg) (p<0.001). Girls were also significantly taller (144.1±7.6 cm) than boys (142.8±6.9 cm) (p<0.001). A significant difference was observed among mean systolic blood pressure in obese children (110.3±14.9 mmHg), overweight children (105.6±11.7 mmHg) and non-obese children (98.2±13.1 mmHg) (p<0.001). Multiple comparisons on Scheffer posthoc test showed that the differences between these three groups were all significant (p=0.001).Conclusions: In both sexes (especially females), inactivity and high-fat school snacks in school-aged children contribute to the increasing prevalence of obesity. To reduce the prevalence of adult obesity and its related diseases, like hypertension, in the future, conducting research in the prevention and/or treatment of childhood obesity is necessary

The effect of calcium on the adhesion of Streptococcus mutans to Human Gingival Epithelial Cells in the presence of probiotic bacteria Lactobacillus plantarum and Lactobacillus salivarius

Introduction: Oral pathogens are among the most common bacterial infections in humans. The adhesion of probiotic bacteria to epithelial cells plays an important role in inhibiting the growth and binding of pathogenic bacteria. We aim to investigate the effect of calcium carbonate on the binding of Streptococcus mutans to Human Gingival Epithelial Cells (HGECs) in the presence of the probiotic bacteria Lactobacillus plantarum and Salivarius. Methods and materials: Experiments are performed in the presence of calcium and probiotic bacteria and HGECs in duplicate and three times separately. The difference in the amount of Streptococcus mutans in HGECs is determined by the presence and absence of Lactobacillus plantarum or salivarius and calcium or both by dilution and culture procedures. Results: Simple effects analysis showed that the survival rate of HGECs in all doses was significantly higher than negatives (p < .001). The results indicated that the survival rate in the single dose of L. salivarius (0.617 ± 0.003) and L. plantarum (0.652 ± 0.002) was significantly higher than the combined doses. Conclusion: This study clearly demonstrates that calcium and probiotics from Lactobacillus salivarius and plantarum alone can improve the survival of HGECs in the presence of Streptococcus mutans. But the combined function of these therapeutic factors is not optimal and even reduces their therapeutic efficacy. © 202

Flexural and Shear Characterization of Geosynthetic Reinforced Asphalt Overlays

In the current study, the flexural and shear characteristics of geosynthetic-reinforced asphalt overlays placed on a pre-cracked old pavement layer are evaluated in two different stages. The unreinforced and geosynthetic reinforced two-layered asphalt beam specimens with 40 mm deep notch (crack) in the bottom layer are tested under repeated four-point bending test and interface shear strength test equipments to understand the flexural and shear characteristics, respectively. The two-layered asphalt specimen consists of a 45 mm thick old pavement layer extruded from an existing highway as a bottom layer, a binder tack coat, an interlayer and finally a hot mix asphalt (HMA) overlay. Two different types of geosynthetic-interlayers, namely, biaxial polyester grid coated with polymer modified binder having a square aperture of 18 mm (PET) and a glass-grid composite (GGC) are used in the study. The flexural fatigue and interface shear strength test results indicate that the reinforced specimens improved the fatigue life of overlays and among them, the performance of GGC specimens are superior. However, the inclusion of geosynthetic-interlayers at the interface of old and new layers reduce the interface shear strength, resulting in a possible delamination of the pavement layers. A reduction of 17% and 36% in interface shear strength was witnessed in PE, and GGC reinforced specimens, respectively. Overall, the geosynthetic-interlayers improved the performance life of asphalt overlays invariably, before failure