Bioactivity and Surface Characteristics of Titanium Implants Following Various Surface Treatments: An In Vitro Study.

This study compared the surface topography, hydrophilicity, and bioactivity of titanium implants after 3 different surface treatments (sandblasting and acid etching, modified sandblasting and acid etching, and thermal oxidation) with those of machined implants. One hundred indigenously manufactured threaded titanium implants were subjected to 3 methods of surface treatment. The surface roughness of the nontreated (Group A) and treated samples (Groups B through D) was evaluated with a scanning electron microscope (SEM) and profilometer. The wettability was visually examined using a colored dye solution. The calcium ions attached to the implant surface after immersing in simulated body fluid (SBF) were assessed on days 1, 2, and 7 with an atomic electron spectroscope. The data were analyzed statistically. The SBF test allowed the precipitation of a calcium phosphate layer on all surface-treated samples, as evidenced in the SEM analysis. A significantly higher amount of calcium ions and increased wettability were achieved in the thermally oxidized samples. The mean roughness was significantly lower in Group A (0.85 ± 0.07) compared to Group B (1.35 ± 0.17), Group C (1.40 ± 0.14), and Group D (1.36 ± 0.18). The observations from this in vitro study indicated that surface treatment of titanium improved the bioactivity. Moreover, results identified the implants that were sandblasted, acid etched, and then oxidized attracted more calcium ions.

Dynamics of sustainable grazing fauna and effect on performance of gas biofilter.

The inherent operational problems of biofilters such as a pressure drop increase and nutrient limitations were managed in a toluene-removing gas biofilter with a sustainable grazing fauna consisting of micrometazoa and ciliate protozoa. Dynamic populations of predatory nematodes (Caenorhabditis sp.), rotifers (Philodina sp.), tardigrades (Echiniscus sp.) and fly larvae represented the micrometazoa community in the filter bed. Colpoda inflata, Euplotes harpa and Acineria sp. constituted the grazing ciliate community. The spatiotemporal distribution and abundance of the grazing fauna depends on physicochemical conditions and interspecies interactions in the biofilter. Of the micro metazoa, Caenorhabditis and Philodina tolerated wide concentration ranges for toluene (0.75-2.63 g m(-3)) and CO(2) (0.92-6.08 g m(-3)) and maintained stable populations of 3.4-4.7 x 10(3) and 5.8-7.65 x 10(4) g medium(-1), respectively. The grazing fauna supported a stable toluene-degrading bacterial community composed of four Pseudomonas spp. Under a maximum toluene load of 120.72 g m(-3) h(-1), at steady-state conditions 80% toluene removal was achieved in the biofilter. Of the grazing organisms, owing to their reproductive cycle and feeding behaviour, fly larvae were not suited for application in the biofilter. Meanwhile, organisms such as nematodes, rotifers and ciliates capable of tolerating a wide pollutant concentration range and maintaining a sustainable population are ideal candidates for application in biofilter technology.