Hydrophobic titania–silica aerogels: epoxidation of cyclic compounds

Topics in Catalysis - Titania–silica mixed oxides with covalently bound methyl or phenyl groups were prepared from the corresponding alkyltrimethoxysilane and tetramethoxysilane using a...     

Influence of stiffness and shape of contact surface on skull fractures and biomechanical metrics of the human head of different population underlateral impacts

The objective of this study was to determine the responses of 5th-percentile female, and 50th- and 95th-percentile male human heads during lateral impacts at different velocities and determine the role of the stiffness and shape of the impacting surface on peak forces and derived skull fracture metrics. A state-of-the-art validated finite element (FE) head model was used to study the influence of different population human heads on skull fracture for lateral impacts. The mass of the FE head model was altered to match the adult size dummies. Numerical simulations of lateral head impacts for 45 cases (15 experiments × 3 different population human heads) were performed at velocities ranging from 2.4 to 6.5 m/s and three impacting conditions (flat and cylindrical 90D; and flat 40D padding). The entire force-time signals from simulations were compared with experimental mean and upper/lower corridors at each velocity, stiffness (40 and 90 durometer) and shapes (flat and cylindrical) of the impacting surfaces. Average deviation of peak force from the 50th male to 95th male and 5th female were 6.4% and 10.6% considering impacts on the three impactors. These results indicate hierarchy of variables which can be used in injury mitigation efforts.     

Radon measurement in schools located in three priority investigation areas in the province of Quebec, Canada

The purpose of this study was to measure radon concentration in public primary schools located in priority investigation areas, with the aim of decreasing occupants' exposure to radon in public buildings where concentrations exceed the Canadian Federal guidelines (i.e. 200 Bq m(-3)). In addition, the association between radon levels, substratum geological characteristics and schools' structural characteristics were investigated. The results showed that radon concentrations measured in the 65 investigated schools are generally below the Federal guideline levels. Eleven schools (17 %) had at least one measurement above the Federal guideline, while one had a level above 600 Bq m(-3). On average, targeted schools' occupants are exposed to radon concentrations of 56 Bq m(-3). Although statistical analysis, which was limited by the sample size, did not show any link between aggregated radon measurements and geochemical or radiological signatures of investigated sites, the geological evidence that led to the choice of the studied regions remains relevant.     

Impact dynamics of metal foam shells for motorcycle helmets: Experiments & numerical modeling

To reduce the weight of motorcycle helmet, metal foam for outer shell in place of conventional thermoplastics was tested. The dynamic behaviour of this new helmet was studied through experiments and numerical modeling. Open-face motorcycle helmets were designed with metal foam shell and impact experiments were performed with these helmets fitted on a headform. A finite element model was developed and the predicted acceleration of headform from this model was validated against the experiments. The mechanical behaviour of full-face helmets with metal foam shell was investigated next. The FE analysis was performed separately with rigid and deformable heads. Head injury criterion (with rigid head) and stresses in brain (with deformable head) were evaluated separately for metal foam shell and ABS shell helmets. The helmet impact performance is examined with two separate densities of metal foam. The shell with low-density metal foam (150 kg/m³) gives a better performance compared to ABS shell. The metal foam shell showed significant visible plastic deformation in the impact region.     

Kappa-Carrageenan Effects on the Gelation Properties of Simulated Oven-roasted Turkey Breast Juice

The gelling mechanism in oven-roasted turkey breast juice and the effects of k-carrageenan and certain salts were evaluated. In the presence of 2.2% salt and 0.5% phosphate, the soluble protein started to gel at 52°C, and k-carrageenan started to swell at 46°C during heating and gel at 44°C during cooling. When sodium chloride content was changed to 0% or 4.4% and phosphate content to 0% or 1.2%, k-carrageenan started to swell at 28°C and gel at 36°C, or swell at 67°C and gel at 55°C, respectively. The protein and k-carrageenan combination showed a significant (P<0.05) synergistic increase in final gel strength; the effect was increased further (P<0.05) by 0.2% added potassium chloride or calcium chloride.     

Mechanical construction and computer architecture of thefour-legged walking machine BISAM

Presents a biologically inspired design of a four-legged walking machine. It offers the possibility to investigate reptile- and mammal-like walking with one mechanical concept. A flexible spinal column will support walking with better stability. For the control of the machine, a hierarchical organized computer architecture and a modular software concept are presented     

Effect of physical fitness on vanillylmandelic acid excretion during immersion

The effects of 4--6 h head-out immersion on excretion of vanillylmandelic acid (VMA), blood pressure and plasma volume were estimated in 8 endurance-trained (TR) and 8 untrained (UT) subjects. In the trained only a slight increase of VMA excretion occurred (4 h value: +2.7 +/- 10.9 ng/ml GFR), but there was a highly significant increase in the UT (+29.0 +/- 17.2 ng/ml GFR). VMA values during control experiments in supine position tended to decrease in both groups. Systolic and diastolic blood pressure fell by 20 mm Hg after beginning of immersion; in the UT plasma volume was reduced while it remained constant in TR. The results indicate that orthostatic intolerance (o.i.) after immersion is not effected by decreased sympathetic innervation of vessels; in contrast it seems to be partly compensated for by an elevated sympathetic activity at least in the UT. As a main cause for the post-immersion o.i. one might suggest a decrease in renin activity.