Arching Action Revisited

Reinforced concrete and elastic-tensionless strips transversally loaded and restrained against longitudinal displacements at supports are considered. The support restraints induce important axial forces and that results in a highly nonlinear and unstable character of the structure response. A commercial FEM code is used and the results are compared with those obtained from an approximate approach based upon the post-yield methodology, proposed years ago by the authors. The latter approach neglects elastic flexural deformations but accounts for axial compliance of the system and furnishes simple analytical expressions for the load vs. displacement relations. It appears from the FEM analysis that the flexural compliance has a negligible impact on the peak-load behaviour. The approximate approach gives satisfactory results, when compliance moduli for the structure and for restraining walls are appropriately chosen. Benchmark cases considered allowed for a proposition concerning determination of these moduli

Cadmium-tolerant rhizospheric bacteria of the C3C_{3}/CAM intermediate semi-halophytic common ice plant (Mesembryanthemum crystallinum L.) grown in contaminated soils

The common ice plant, Mesembryanthemum crystallinum L., has recently been found as a good candidate for phytoremediation of heavy-metal polluted soils. This semi-halophyte is a C(3)/CAM (Crassulacean acid metabolism) intermediate plant capable of tolerating extreme levels of cadmium in the soil. The aim of the work was to obtain and characterize novel, Cd-tolerant microbial strains that populate the root zone of M. crystallinum performing different types of photosynthetic metabolism and growing in Cd-contaminated substrates. The plants exhibiting either C(3) or CAM photosynthesis were treated for 8 days with different CdCl(2) doses to obtain final Cd concentrations ranging from 0.82 to 818 mg⋅kg(–1) of soil d.w. The CAM phase was induced by highly saline conditions. After treatment, eighteen bacterial and three yeast strains were isolated from the rhizosphere and, after preliminary Cd-resistance in vitro test, five bacterial strains were selected and identified with a molecular proteomics technique. Two strains of the species Providencia rettgeri (W6 and W7) were obtained from the C(3) phase and three (one Paenibacillus glucanolyticus S7 and two Rhodococcus erythropolis strains: S4 and S10) from the CAM performing plants. The isolates were further tested for Cd-resistance (treatment with either 1 mM or 10 mM CdCl(2)) and salinity tolerance (0.5 M NaCl) in model liquid cultures (incubation for 14 days). Providencia rettgeri W7 culture remained fully viable at 1 mM Cd, whereas Rh. erythropolis S4 and S10 together with P. glucanolyticus S7 were found to be resistant to 10 mM Cd in the presence of 0.5 M NaCl. It is suggested that the high tolerance of the common ice plant toward cadmium may result from the synergic action of the plant together with the Cd/salt-resistant strains occurring within rhizospheral microbiota. Moreover, the isolated bacteria appear as promising robust microorganisms for biotechnological applications in bio- and phytoremediation projects

ROOBockey Autonomous Hockey Robot

The goal of the ROOBockey project is to design and construct a floor hockey robot that can competitively shoot a puck. The robot design quickly locates a specific beacon through the use of image processing and uses a pneumatic shooting mechanism to send a puck to a specified target. The beacons act as possible player or goal positions in a hockey game. The robot also utilizes a wireless controller device to allow a user to maneuver the robot across a hockey field