An assessment of in vivo failures of alumina ceramic total hip joint replacements

Several cases of alumina ceramic hip replacement failures are reviewed fractographically. Three main findings are illustrated. Firstly, there is evidence that surgeons can damage the femoral head bore surface during surgery. Secondly, three of the failures described are of extended neck designs which are weaker than those of normal or short length in axial laboratory testing. Under physiological loading, such geometry can lead to levering forces, inappropriate localized contact with the metallic stem and stress concentrations. Delayed failure can ensue, with a fracture pattern quite different from that seen in conventional uniaxial testing. Thirdly, while some failures show head bore surfaces which are clean apart from metallic witness marking, others show brown stains and white deposits suggesting poor conformal contact. We suspect either stems become damaged during surgery before mounting the head or entrapment of debris, pointing to handling care and cleanliness varying between hospitals.     

Degradation of neonicotinoid insecticides by different advanced oxidation processes and studying the effect of ozone on TiO2 photocatalysis

Although some studies concerning the effect of pH and ozone dosage on TiO₂ photocatalysis (O₂/TiO₂/UV) have already been published, no complete investigation and explanation of the effects of both parameters on photocatalytic ozonation (O₃/TiO₂/UV) have been carried out. Aqueous solutions of neonicotinoid insecticides (thiacloprid and imidacloprid) were chosen as a degradation medium, since they exhibit a high threat for aquatic systems and it is of great importance to find an effective method for their elimination from the environment. In preliminary stability tests, thiacloprid showed higher photo- and chemical stability compared to imidacloprid, therefore its degradation was studied in detail. To assess the suitability of various treatments for degradation and mineralization of thiacloprid in water at different pH values and ozone dosages, we applied ozonation (O₃) and three different photochemical advanced oxidation processes, namely ozonation, coupled with UV radiation (O₃/UV), O₃/TiO₂/UV and O₂/TiO₂/UV. Light source emitting mainly in UVA range was applied in all three processes. The photocatalytic ozonation (O₃/TiO₂/UV) was found to be the most efficient process irrespective of pH. The synergistic effect of ozone and TiO₂ photocatalysis was noticed at acidic and neutral pH, but the synergism was lost at basic pH, probably due to faster self-decompositon of ozone under alkaline conditions. At acidic pH, also the oxidation of chloride anions to chlorate(V) was noticed in O₃/TiO₂/UV and in O₃/UV processes. By plotting the disappearance rate constants of thiacloprid degradation in O₃/TiO₂/UV and O₃/UV systems as a function of the flow rate of ozone, the synergistic effect of ozone was undoubtedly proven. The slope of the linear fit in case of O₃/TiO₂/UV process was considerably steeper than in case of O₃/UV, which would not happen in absence of synergistic effect. The linearity in O₃/TiO₂/UV system was lost only at very high flow rates of ozone.     

Bioscouring and bleaching of cotton with pectinase enzyme and peracetic acid in one bath

Acidic and alkaline pectinases have proved efficient for the scouring of cotton. Peracetic acid can be used as an alternative for the bleaching of cotton. As a result of similar conditions of activity, we decided to try to scour and bleach a cotton fabric with both agents simultaneously in a single bath. Prior to performing these experiments, using the viscometric method we proved that pectinases retained their activity in the presence of peracetic acid. We tried to improve the efficiency of the single-bath treatment with the addition of a chelator. Tetrasodium pyrophosphate, which does not deactivate pectinases, has proved an efficient chelator. The analyses of a cotton fabric treated in a single bath with acidic and alkaline pectinases confirmed the efficiency of such treatment. A sufficient quantity of wax and pectin was removed and, because of that, the absorbance of the treated fabric was improved. The damage to the cotton fibres was negligible and the degree of whiteness obtained was uniform and adequate for further dyeing.     

Anthocyanins and hydroxycinnamic acids of Lambert Compact cherries (Prunus avium L.) after cold storage and 1-methylcyclopropene treatment

Sweet cherries cv. Lambert Compact were treated with 1-methylcyclopropene (1-MCP) at 0, 180 and 360 nL/L for 2 h at 25 °C and then stored at 2–4 °C in refrigerator. Their quality was measured after 12 days of storage in terms of the contents of total and individual anthocyanins and hydroxycinnamic acids, occurrence of rot, and colour change. Colour change was monitored at three day intervals during storage in the CIE L*, a*, b* colour space. 1-MCP did not retard colour change. The contents of total and individual anthocyanins and hydroxycinnamic acids showed no correlation with the colour behaviour of the cherries. All cherries lost their initial shiny red colour on storage, regardless of the treatment. 1-MCP reduced sweet cherry rot at the highest concentration used (360 nL/L) – only 6% were rotten after 12 days in the refrigerator. This differed significantly (P < 0.05) from untreated fruits and those treated with 180 nL/L 1-MCP which resulted on average in 14 and 20% rot (not statistically different P < 0.05), respectively. The occurrence of rot was shown to be correlated with anthocyanin accumulation, (R = 0.62, P < 0.10). The profile of individual anthocyanins and hydroxycinnamic acids in sweet cherry was not affected neither by cold storage nor 1-MCP treatment.