NMR and IR spectroscopy of silica aerogels with different hydrophobic characteristics

Silica aerogels, prepd. by the sol-gel method and dried by the CO2 supercrit. method, were produced from tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMS) in different proportions, to change the proportions of hydrophilic and hydrophobic surface groups. The aerogel hydrophobic or hydrophilic properties were related to their surface structural characteristics. The relative proportion of Si-OH, Si-OCH3 or Si-CH3 groups present on the aerogel pore surface and its silica network structure were detd. by 1H, 29Si and 13C NMR. The results obtained were correlated with the IR transmission spectra. From these data, a possible description of the mixed hydrophilic-hydrophobic nature of the surface of these materials is proposed

Relationships Between Muscular Power and Bone Health Parameters in a Group of Young Lebanese Adults

International audienceThe aim of the current study was to explore the relationships between lower limb muscular power and bone variables (bone mineral content (BMC), bone mineral density (BMD), hip geometry indices and trabecular bone score (TBS)) in a group of young Lebanese adults. 29 young Lebanese men and 31 young Lebanese women whose ages range between 18 and 32 years participated in this study. Body weight and height were measured, and body mass index (BMI) was calculated. Body composition and bone variables were measured by DXA. DXA measurements were completed for the whole body (WB), lumbar spine (L2–L4), total hip (TH) and femoral neck (FN). Hip geometry parameters including cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), strength index (SI) and buckling ratio (BR) were derived by DXA. Trabecular bone score was also derived by DXA. Horizontal jump (HJ), vertical jump, vertical jump maximum power, force-velocity maximum power and 20-m sprint performance were measured or calculated by using validated fitness tests. In men, fat mass percentage was negatively correlated to TH BMD, FN BMD, CSA, CSMI, Z and SI. In women, weight, BMI, lean mass and fat mass were positively correlated to WB BMC, CSMI and Z. Regarding physical performance variables, horizontal jump performance and force-velocity maximal power were positively correlated to TH BMD, FN BMD, CSA and Z in men. Vertical jump maximal power was positively correlated to WB BMC in women. 20-m sprint performance was negatively correlated to FN BMD, CSA, Z and SI in men. In conclusion, the current study suggests that force-velocity maximum power is a positive determinant of BMD and hip geometry indices in men but not in women

Influence of Sarcopenia on Bone Health Parameters in a Group of Elderly Lebanese Men

International audienceSarcopenia is a disease characterized by the loss of muscle mass and strength. The aim of the current study was to explore the influence of sarcopenia on bone health parameters in a group of elderly Lebanese men. To do so, we compared bone health parameters (Bone Mineral Content (BMC), Bone Mineral Density (BMD) and femoral neck geometry indices) in a group of elderly men with sarcopenia and a group of elderly men with normal Skeletal Muscle mass Index (SMI). 23 sarcopenic men (SMI 7 kg/m 2) participated in our study. Body composition and bone variables were measured by Dual-energy X-ray Absorptiometry (DXA). DXA measurements were completed for the Whole Body (WB), Lumbar spine (L1-L4), Total Hip (TH) and Femoral Neck (FN). Hip geometry parameters including Cross-Sectional Area (CSA), Cross-Sectional Moment of Inertia (CSMI), section modulus (Z), Strength Index (SI) and Buckling Ratio (BR) were derived by DXA. Age and height were not significantly different between the two groups. Weight, Body Mass Index (BMI), lean mass, fat mass, appendicular lean mass, SMI, WB BMC, TH BMD, FN BMD, CSA, CSMI and Z were significantly higher in non-sarcopenic men compared to sarcopenic men. In the whole population , lean mass was the strongest determinant of bone health parameters. After adjusting for lean mass, there were no significant differences regarding bone health parameters between the two groups. In conclusion, the present study suggests that sarcopenia negatively influences bone health parameters in elderly Lebanese men