Children's Perceptions of the Dentist and Dental Office Through Drawings.

Purpose: To evaluate children's perceptions of the dentist and dental office using drawings and its association with age, sex, and previous dental experience.
Methods: Participants included 144 four- to six-year-old children who were instructed to make a drawing of their perception of the dentist and dental office. Data collected included age, sex, and previous dental care experience. The data were analyzed descriptively and through multivariate logistic regression.
Results: Boys were 2.3 times more likely to have a negative perception of the dentist than girls (P =0.024). Children who had no previous dental experience were four times more likely to have a negative perception of dentists (P =0.002). Six-year-old children were three times more likely to have a negative perception of the dentist compared to four-year-old children (P =0.031).
Conclusion: Drawings can be a useful tool to evaluate children's perceptions of the dentist and dental office.

Micromesoporous Activated Carbons as Catalysts for the Efficient Oxidation of Aqueous Sulfide.

KOH activation of a mesophase pitch produces very efficient carbons for the removal of sulfide in aqueous solution, increasing the sulfur oxidation rate with the degree of activation of the carbon. These carbons are characterized by their graphitic structures, with domains of sizes of around 20 nm, and a moderate concentration of surface oxygen groups (0.2-0.5 mmol·g-1) dominating the basic groups. Because the activation leads first to a strong development of the micropores and later to a development of the mesopores, the surface area values are always high, reaching values of as high as 3250 m2·g-1 in the most activated carbon, with a volume of mesopores of as high as 44% of the total pore volume. In the presence of this carbon, the sulfide oxidation rate is 100 times higher than that found for a commercial activated carbon, the results indicating that the porosity of the carbon, especially mesoporosity, plays a role more important than the structure or the chemical nature of the carbon in the kinetics of sulfide oxidation to different polysulfides.

Use of iron and bio-oil wastes to produce highly dispersed Fe/C composites for the photo-Fenton reaction.

This work describes the synthesis, characterization, and application of an active heterogeneous photo-Fenton system obtained from two different wastes, i.e., laterite (an iron mining waste) and the acid aqueous fraction (AAF) from bio-oil production. AAF with high acidity (ca. 3 molH+ L-1) and organic concentration (25 wt.%) obtained from biomass flash pyrolysis was used for the efficient extraction of Fe3+ from laterite waste. After extraction, the mixture Fe3+/AAF was dried and treated at different temperatures, i.e., 500, 650, and 800 °C, to obtain Fe/C reactive composites. Mössbauer, XRD, TG, elemental analyses, and SEM/EDS showed the presence of highly disperse Fe oxide nanoparticles at 500 and 650 °C and Fe0 particles in the material obtained at 800 °C with carbon contents varying from 74 to 80 %. The three composites were tested as heterogeneous catalysts in the photo-Fenton reaction for the oxidation of the model dye contaminant methylene blue, showing high activities at neutral pH.

Controlled formation of reactive Fe particles dispersed in a carbon matrix active for the oxidation of aqueous contaminants with H2O2.

In this work, reactive iron nanoparticles dispersed in a carbon matrix were produced by the controlled thermal decomposition of Fe(3+) ions in sucrose. During the sucrose decomposition, the Fe(3+) ions are reduced to form iron nanometric cores dispersed in a porous carbonaceous matrix. The materials were prepared with iron contents of 1, 4, and 8 wt.% and heated at 400, 600, and 800 °C. Analyses by X-ray diffraction, Mössbauer spectroscopy, magnetization measurements, Raman spectroscopy, termogravimetric analyses, BET surface area, scanning, and transmission electron microscopy showed that at 400 °C, the materials are composed essentially of Fe3O4 particles, while treatments at higher temperatures, i.e., 600 and 800 °C, produced phases such as Fe(0) and Fe3C. The composites were tested for the oxidation of methylene blue with H2O2 by a Fenton-type reaction and also H2O2 decomposition, showing better performance for the material containing 8 % of iron heated at 400 and 600 °C. These results are discussed in terms of Fe(2+) surface species in the Fe3O4 nanoparticles active for the Fenton reaction.

Two-step chromatographic purification of recombinant human thyrotrophin and its immunological, biological, physico-chemical and mass spectral characterization.

A purification strategy for rapidly obtaining recombinant human thyrotropin (rhTSH) was designed based on size exclusion and reversed-phase high-performance liquid chromatographic (HPLC) analysis, carried out on hTSH-secreting CHO cell conditioned medium. These analyses permitted the identification of the main contaminants to be eliminated. Considering that hTSH is highly hydrophobic and elutes only with the addition of organic solvents, hydrophobic interaction chromatography was adopted as the first purification step; this resulted in the elimination of, among others, the major contaminant. A second purification step, based on size exclusion chromatography, was then utilized, being effective in the elimination of other previously identified contaminating proteins. Useful purity, as high as 99% at the chemical reagent level, and recoveries (37%) were obtained by adopting this two step strategy, which also provided adequate material for physico-chemical, immunological and biological characterization. This included matrix-assisted laser desorption ionization time-of-flight mass spectral analysis (MALDI-TOF-MS), Western blotting analysis, in vivo biological assay, size-exclusion HPLC (HPSEC) and reversed-phase HPLC (RP-HPLC) analysis, which confirmed the integrity and bioactivity of our rhTSH in comparison with the only two reference preparations available at the milligram level of native (hTSH-NIDDK) and recombinant (Thyrogen) hTSH. Thyrogen and rhTSH-IPEN, when compared to pit-hTSH-NIDDK, presented more than twice as much biological activity and about 7% increased molecular mass by MALDI-TOF-MS analysis, an accurate heterodimer mass determination providing the Mr values of 29,611, 29,839 and 27,829, respectively. The increased molecular mass of the two recombinant preparations was also confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and HPSEC analysis. Comparing the two recombinant preparations, minor though interesting physico-chemical and biological differences were also observed.

Determination of Chinese hamster ovary cell-derived recombinant thyrotropin by reversed-phase liquid chromatography.

A reversed-phase high-performance liquid chromatography (RP-HPLC) methodology for the qualitative and quantitative analysis of human thyrotropin (hTSH) in CHO cell conditioned medium and in purified preparations has been set up and validated for accuracy, precision and sensitivity. A recovery test indicated a bias of less than 2% and intra-day and inter-day quantitative determinations presented relative standard deviations (RSD) always <7%, while sensitivity was 0.2 microg (RSD=5.6%). The novel methodology was applied to the study of the best cultivation conditions and was able to detect a significant difference in retention time (t(R)) between pituitary and recombinant hTSH, probably reflecting the influence of the heterogeneity of the carbohydrate moiety on the hydrophobic properties of the molecule.