Experimental and finite element investigation of void nucleation in rubber-like materials

International audienc

QUANTITATIVE ANALYSIS OF CARBON BLACK AGGLOMERATES MORPHOLOGY IN ELASTOMER COMPOSITES BASED ON X-RAY TOMOGRAPHY BY MEANS OF NUMERICAL CLUSTERING

International audienceABSTRACT A novel methodology for characterizing the morphology distribution of filler agglomerates in elastomer composites is presented based on laboratory-sourced X-ray tomography. Various feature extraction methods (via, e.g., image-processing filters, segmentation) and selection tools (Spearman's rank correlation coefficient) combined with K-means unsupervised clustering algorithm were developed for identifying the distinct morphological classes in model materials (carbon-filled ethylene propylene diene monomer rubber). The interest of this methodology was demonstrated by precisely differentiating the materials compounded with different processing parameters. For instance, in this example, thanks to this analysis, it was found that introducing the filler before the elastomer in internal mixer tends to favor more structured agglomerates

Pulsed Electromognetic field affects the intracellular calcium concentration in human astrocytoma cells

6nononeExperiments assessed whether long term exposure to 50 Hz pulsed electromagnetic fields with a peak magnetic field of 3 mT can alter the dynamics of intracellular calcium in human astrocytoma U-373 MG cells. Pretreatment of cells with 1.2 μM substance P significantly increased the [Ca2+]i. The same effect was also observed when [Ca2+]i was evaluated in the presence of 20 mM caffeine. After exposure to electromagnetic fields the basal [Ca2+]i levels increased significantly from 143 ± 46 nM to 278 ± 125 nM. The increase was also evident after caffeine addition, but in cells treated with substance P and substance P + caffeine we observed a [Ca2+]i decrease after exposure. When we substituted calcium-free medium for normal medium immediately before the [Ca2+]i measurements, the [Ca2+]i was similar to that measured in the presence of Ca2+. In this case, after EMFs exposure of cells treated with substance P, the [Ca2+]i, measured without and with addition of caffeine, declined from 824 ± 425 to 38 ± 13 nM and from 1369 ± 700 to 11 ± 4 nM, respectively, indicating that electromagnetic fields act either on intracellular Ca2+ stores or on the plasma membrane. Moreover the electromagnetic fields that affected [Ca2+]i did not cause cell proliferation or cell death and the proliferation indexes remained unchanged after exposure. © 2001 Wiley-Liss, Inc.nonePESSINA, G.P.; ALDINUCCI, C.; PALMI, M.; SGARAGLI, G.P.; BENOCCI, A.; PESSINA, F.Pessina, G. P.; Aldinucci, C.; Palmi, M.; Sgaragli, G. P.; Benocci, A.; Pessina, F

A role for galanin in antidepressant actions with a focus on the dorsal raphe nucleus

Selective serotonin reuptake inhibitors, such as fluoxetine (FLX), are the most commonly used drugs in the treatment of major depression. However, there is a limited understanding of their molecular mechanism of action. Although the acute effect of selective serotonin reuptake inhibitors in elevating synaptic serotonin concentrations is well known, the clinical amelioration of depressive symptoms requires 14-21 days of treatment, suggesting that numerous other rearrangements of function in the CNS must take place. In the present study, we demonstrated that 14 days of FLX treatment up-regulated galanin mRNA levels by 100% and GalR2-binding sites by 50%, in the rat dorsal raphe nucleus, where galanin coexists with serotonin. Furthermore, a galanin receptor antagonist, M40, attenuated the antidepressant-like effect of FLX in the forced swim test, a rodent preclinical screen commonly used to evaluate antidepressant-like efficacy. Direct activation of galanin receptors by a galanin receptor agonist, galnon, was found to produce an antidepressant-like effect in the same task. Two other antidepressant treatments also affected the galaninergic system in the monoaminergic nuclei: Electroconvulsive shock elevated galanin mRNA levels in dorsal raphe nucleus, whereas sleep deprivation increased galanin mRNA levels in the locus coeruleus, further underlining the connection between activation of the galaninergic system and antidepressant action of various clinically proven treatments