MICROANALYSE X DES ISOLANTS (SIMULATIONS DE MONTE-CARLO)

REIMS-BU Sciences (514542101) / SudocSudocFranceF

Shock Response Spectrum Analysis of Fatigued Runners

International audienceThe purpose of this study was to determine the effect of fatigue on impact shock wave attenuation and assess how human biomechanics relate to shock attenuation during running. In this paper, we propose a new methodology for the analysis of shock events occurring during theproposed experimental procedure. Our approach is based on the Shock Response Spectrum (SRS), which is a frequency-based function that is used to indicate the magnitude of vibration due to a shock or a transient event. Five high level CrossFit athletes who ran at least three times per week and who were free from musculoskeletal injury volunteered to take part in this study. Two Micromachined Microelectromechanical Systems (MEMS) accelerometers (RunScribe®, San Francisco, CA, USA) were used for this experiment. The two RunScribe pods were mounted on top of the foot in the shoelaces. All five athletes performed three maximum intensity runs: the 1st run was performed after a brief warmup with no prior exercise, then the 2nd and the 3rd run were performed in a fatigued state. Prior to the 2nd and the 3rd run, the athletes were asked to perform at maximum intensity for two minutes on an Assault AirBike to tire them. For all five athletes, there was a direct correlation between fatigueand an increase in the aggressiveness of the SRS. We noticed that for all five athletes for the 3rd run the average SRS peaks were significantly higher than for the 1st run and 2nd run (p < 0.01) at the same natural frequency of the athlete. This confirms our hypothesis that fatigue causes a decrease in the shock attenuation capacity of the musculoskeletal system thus potentially involving a higher risk of overuse injury

Non-Thermal O2 Plasma Efficacy on C. albicans and Its Effect on Denture Base Resin Color

International audienceDenture stomatitis is a disease involving C. albicans, which can affect elderly and immunocompromised people. To avoid any recurrence of this pathology, it is necessary to treat patients regularly and disinfect dentures. However, the denture cleansers’ efficacy is not optimal and often leads to adverse color effects on the denture base resins. The aim of this study was to investigate the efficacy of a low-pressure non-thermal O2 plasma (NTP) treatment on C. albicans seeded on ProBase®Hot resin (Ivoclar Vivadent). The viability reduction of C. albicans was assessed by colony forming units (CFU) analysis and by scanning electron microscopy (SEM). The effect of repeated treatments on the resin color was evaluated by spectrophotometry. The resin samples were placed in a sealed bag in which O2 plasma was generated in low-pressure conditions. The results showed that a 120-min O2 NTP treatment led to a 6-log reduction of C. albicans viability (p < 0.05) and to yeasts’ major alterations observed by SEM. Furthermore, significant slight color changes of the resin (DE00 = 1.33) were noted only after six plasma treatments (p < 0.05). However, the denture aesthetic was preserved, as the color changes were not perceptible and remained below the acceptability threshold (DE00 < 4)