Detecting microscopic defects in aged thermoplastic using thermoelastic technique
An experimental investigation into the thermoelastic technique applied on a thermoplastic material is presented. The TSA response in PEEK polymer after it has been exposed to methane at elevated temperatures was used to establish whether microscopic defects in the PEEK material can be detected using thermoelastic measurement. Utilising a combination of high resolution lenses and sensitivity of the detectors, the TSA method was able to detect and sizing of surface damage. The size of the defect was approximately 300 μm. However the subsurface damage was untraceable by the technique.
Introduction to thermoelastic stress analysis
The theory of thermoelastic stress analysis is reviewed and the assumptions in developing the theory are assessed. The equipment for thermoelastic stress analysis is based on infrared detection systems. The commercially available systems are described and appraised. Techniques for calibrating the output from the detectors are also provided.
Denitrification of PVA-immobilized denitrifying photosynthetic bacterium, Rhodobacter sphaeroides
Abstract A newly isolated denitrifying strain, Rhodobacter sphaeroides NII2 was immobilized in polyvinyl alcohol (PVA) gel, and the properties of the cells in the gel were examined. The immobilized cells had low or almost no denitrification activity, but the cells were activated by incubation in light with culture medium for denitrification containing 0.5% nitrate and no other nitrogen source. Cells grown in the dark were activated by incubation at an earlier stage and to a higher rate than the light-grown cells. The activation was markedly enhanced in the PVA gel with a low cell concentration. The immobilized cells consumed nitrate with a temporary accumulation of NO 2 and evolved nitrogen gas. The immobilized cells could use various organic compounds as electron donors for denitrification. Thus, the immobilized cells were applied to a continuous treatment of synthetic wastewater using an aparatus devised by this laboratory. The results showed an efficient removal of NO 3 -N from the test water.