ABSTRACT
Interconnection, one of the main structural features of macroporous calcium-phosphate ceramics, contributes to the biological and physicochemical properties of bone substitutes. As no satisfactory method exists for evaluating this feature, analysis was performed to determine the permeability, tortuosity, and equivalent diameter of interconnecting channels, that is the parameters that appear to be representative of the way pores are linked. The testing of two ceramics with similar porosity levels revealed important differences in all three interconnection parameters. One ceramic showed poor permeability, corresponding to a small equivalent diameter for interconnecting channels in conjunction with a high tortuosity factor, while the other displayed high permeability, a large diameter for interconnecting channels, and a low tortuosity factor. The methodology used, which can be applied to the quantification of interconnection in all calcium-phosphate ceramics, constitutes the first step in a complete study of the role of this feature in cellular colonization of the ceramic, matrix dissolution, and drug release from the calcium-phosphate matrix.
Subject(s)
Biocompatible Materials/chemistry , Calcium Phosphates/chemistry , Ceramics/chemistry , Algorithms , Biocompatible Materials/chemical synthesis , Calcium Phosphates/chemical synthesis , Ceramics/chemical synthesis , Diffusion , Iodides/chemistry , Mercury/chemistry , Models, Chemical , Permeability , Porosity , Spectrometry, Mass, Electrospray IonizationABSTRACT
Zinc determination in serum microsamples can be treated by graphite furnace atomic absorption spectrometry. To reduce the contamination risks and to obtain results as right as possible, the serum has been twenty fold diluted instead of 100-fold diluted (rate frequently obtained). In these conditions, the use as diluent of a 1% Triton X 100 solution or of a 33.7 mmol/l magnesium nitrate did not allow to obtain exact results. Yet, with an 37.8 mmol/l ammonium phosphate solution, the results given by the direct calibration on an aqueous calibration curve were in good accordance with those found with a recommended flame atomic absorption spectrometry method. The within-run RSD of our method was 2.6%.
Subject(s)
Zinc/blood , Humans , Phosphates , Spectrophotometry, Atomic/methods , TemperatureABSTRACT
Immunoenzymatic test, EMIT Tox, proposed for qualitative and semi quantitative determination of toxicological levels of benzodiazepines in serum is compared with gas chromatography. When used for qualitative purposes in 102 sera, the EMIT Tox test gave 5% error. In semi quantitative determinations, the EMIT Tox test was applied to 139 sera with one or more of the three benzodiazepines (oxazepam, desmethyldiazepam, diazepam), showing a significant correlation with levels measured by gas chromatography; but the EMIT Tox test frequently yields values too low for elevated oxazepam and desmethyldiazepam concentrations.