19 research outputs found
Aseptic Loosening of Total Hip Arthroplasty as a Result of Local Failure of Tissue Homeostasis
Surgical procedures in the treatment of 784 infected THAs reported to the Norwegian Arthroplasty Register: Best survival with 2-stage exchange revision, but also good results with debridement and retention of the fixed implant
TiO2-anatase films made by sol-gel processing and their photodegradation activity towards pollutants in water
Titanium dioxide has become the material of choice for hydrophilic photocatalytic
surfaces and the sol-gel technique has emerged as one of the most promising techniques for
growing TiO2 thin films. This chapter describes our sol-gel preparation and utilization of thin
titania films on glass substrates as catalysts for photodegradation of organic pollutants, such as
azo dyes and pesticides in aqueous solutions. The good photoefficiency of the as-prepared films
relies on their high contact surface area and nanocrystalline structure, which facilitates efficient
photoinduced electron-hole pair generation.
Transparent TiO2-anatase films on soda-lime glass supports were produced by two
different sol-gel processing routes: (i) dip coating from alcoholic sols containing surfactants and
followed by heat treatment at 500\ub0C; (ii) dip coating from aqueous sols after extended refluxing
treatment and followed by heating at ~100\ub0C. In both cases the starting precursor was titanium
alkoxide and the final coating consisted of a dominant anatase crystalline phase. In case of the
high-temperature processing route, the detrimental effect of interdiffused sodium ions from the
glass substrate during heat treatment was prevented by depositing a thin silica barrier layer prior
to titania deposition. The intermediate barrier layer was not needed in case of the lowtemperature
processing route, where the crystallization of anatase has been already promoted
during the formation of the sol. X-ray absorption spectroscopy and X-ray diffraction were applied
to determine the structure development at different stages from the precursor solution to the solid
thin film. Surface morphology, characterized by monodispersed or joint nanoparticles and
variable roughness, was investigated with atomic force microscopy, while the surface and indepth
composition of films were analyzed by X-ray photoelectron spectroscopy.
A photocatalytic activity of the as-prepared films was studied in two different tailor-made
photoreactors filled with an aqueous solution of certain pollutant. In case of an azo dye, the films
were immersed in its colored solution and photobleaching was followed in-situ with the help of
UV-VIS spectroscopy. The degradation of the pesticide was monitored by HPLC analysis and its
mineralization by ionic chromatography. The insecticide thiacloprid was stable under irradiation
(wavelength range 310-400 nm) in the absence of TiO2 films during 8 hours long period, whereas
in the presence of best-performing titania films the half time of the parent molecule was typically
15 minutes. The titania catalyst can be easily removed from the solution, which is one of the
principal advantages of using the immobilized films as catalysts rather than powders
Photocatalytically active TiO2 thin films produced by surfactant-assisted sol-gel processing
Thin TiO2 films were prepared from a titanium isopropoxide precursor by sol\u2013gel processing with or without various nonionic surfactant molecules (Brij 56, Triton X-100 or Pluronic F-127). The photocatalytic efficiency of the transparent films obtained by a dip-coating technique was found to depend strongly on the use of and type of surfactant added. Titania/Pluronic sols resulted in homogeneous and crack-free TiO2 anatase films with a thickness as much as 300 nm after one dipping and heat-treatment (500 \ub0C) cycle. Optical properties of the films were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol\u2013gel process retarded crystallization of the anatase titania films, which resulted in smaller grain sizes (down to 10 nm) and presumably a larger active surface area. The morphology of the film surfaces as obtained by SEM techniques could be also correlated with the results of our photodegradation studies. The photocatalytic activity of the films was enhanced by first coating the glass substrate with a SiO2 protective layer prior to the deposition of the titania film. For our in situ studies of photodegradation we chose the monoazo dye Plasmocorinth B as a model compound as it is stable under environmental conditions and its degradation products are not coloured. The highest photobleaching rate was found for films deposited from the sol with addition of the Pluronic surfactant and it was almost twice as high as that for films deposited from sols without the surfactant
Toxicity of imidacloprid to the terrestrial isopod Porcellio scaber (Isopoda, Crustacea).
The influence of malathion and its decomposition products on free and immobilized acetylcholinesterase
The influence of malathion and its four main degradation products found in irradiated solutions (malaoxon, isomalathion, diethyl maleate and O,O-dimethyl phosphate) on acetylcholinesterase (AChE) of free and immobilized bovine erythrocytes was investigated. The concentration-dependent responses to malathion and related organophosphates, malaoxon and isomalathion, of both AChE bioassays used were obtained. The IC (50) values for free and immobilized AChE (3.7 +/- 0.2) x 10(-4) M/(1.6 +/- 0.1) x 10(-4), (2.4 +/- 0.3) x 10(-6)/(3.4 +/- 0.1) x 10(-6) M, and (3.2 +/- 0.3) x 10(-6) M/(2.7 +/- 0.2) x 10(-6) M were obtained in the presence of malathion, malaoxon and isomalathion, respectively. However, diethyl maleate inhibited AChE activity at concentrations GT = 10 mM, while O,O-dimethyl phosphate did not noticeably affect enzyme activity at all investigated concentrations. The relation between the structure of the compounds and their ability to inhibit enzyme activity was discussed
Detection of bacteria with molecular methods in prosthetic joint infection
Background and purpose — The correct diagnosis of prosthetic joint infection (PJI) can be difficult because bacteria form a biofilm on the surface of the implant. The sensitivity of culture from sonication fluid is better than that from periprosthetic tissue, but no comparison studies using molecular methods on a large scale have been performed. We assessed whether periprosthetic tissue or sonication fluid should be used for molecular analysis. Patients and methods — Implant and tissue samples were retrieved from 87 patients who underwent revision operation of total knee or total hip arthroplasty. Both sample types were analyzed using broad-range (BR-) PCR targeting the 16S rRNA gene. The results were evaluated based on the definition of periprosthetic joint infection from the Workgroup of the Musculoskeletal Infection Society. Results — PJI was diagnosed in 29 patients, whereas aseptic failure was diagnosed in 58 patients. Analysis of sonication fluid using BR-PCR detected bacteria in 27 patients, whereas analysis of periprosthetic tissue by BR-PCR detected bacteria in 22 patients. In 6 of 7 patients in whom BR-PCR analysis of periprosthetic tissue was negative, low-virulence bacteria were present. The sensitivity and specificity values for periprosthetic tissue were 76% and 93%, respectively, and the sensitivity and specificity values for sonication fluid were 95% and 97%. Interpretation — Our results suggest that sonication fluid may be a more appropriate sample than periprosthetic tissue for BR-PCR analysis in patients with PJI. However, further investigation is required to improve detection of bacteria in patients with so-called aseptic failure