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Volatile species of Ag, Au, Cu, Zn, Cd, and As were generated at room temperature by the addition of sodium tetrahydroborate(III) to an acidified solution of the analytes. The vapor-phase species were rapidly transported to a heated quartz tube atomizer (QTA) for detection by atomic absorption spectrometry. A univariate approach was used to achieve optimized conditions and derive analytical figures of merit. The analytes are released from solution as molecular species (likely as metal hydrides) and are (partially) atomized in the QTA under nonoptimized conditions. Detection limits range from 1.8 (Zn) to 420 ng (Au). The efficiency of the generation process is estimated to be 92 +/- 4% for Au. Loss of analyte during transport to the QTA was minimized through use of the minimum length of narrow-bore Teflon transfer line possible.

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De‐Deus G, Brandão MC, Leal F, Reis C, Souza EM, Luna AS, Paciornik S, Fidel S. Lack of correlation between sealer penetration into dentinal tubules and sealability in nonbonded root fillings. International Endodontic Journal, 45, 642–651, 2012. Abstract Aim  To determine the correlation between leakage and sealer penetration into dentinal tubule. Methodology  The root canal of 60 mandibular central incisor teeth were prepared and filled under standardized conditions. Teeth were placed into a device to assess glucose penetration using 15 psi pressure application. After 1 h, glucose concentrations in the lower chamber were measured using an enzymatic reaction. Each specimen was then sectioned horizontally at 3, 6 and 8 mm from the apex, and a standard metallographic preparation was performed. The coronally facing surface of each slice was examined in a high‐resolution stereomicroscope and under Confocal Laser Scanning Microscope. For each slice, the external outline of the root canal, the internal circumference of the root canal walls and the areas along the canal walls where the sealer had penetrated into the dentinal tubules (sealer tags) were outlined and measured. Afterwards, the percentage of the sealer penetration in each section was calculated. The Spearman correlation test was used to verify the correlation between the variables studied (glucose leakage and sealer penetration into dentinal tubules). Results  The means and standard deviations of glucose leakage were 0.744 g L−1 (±0.5), and the percentage of the dentinal tubule sealer penetration varied between teeth from 5.6% to 42.21%, with an average of 13.7 ± 17.2%. The Spearman correlation test revealed no significant correlation between the two factors analysed (P = 0.082). The r2 value was equal to 0.12. Conclusions  There was no significant correlation between sealability sealer penetration into dentinal tubles. The lack of correlation reported is of relevance as sealer penetration into dentinal tubules has been used as an advantageous property during the launch of new root filling materials and techniques.

Leal F, De-Deus G, Brandã o C, Luna AS, Fidel SR, Souza EM. Comparison of the root-end seal provided by bioceramic repair cements and White MTA. International Endodontic Journal, 44, 662-668, 2011.Aim To compare the ability of Ceramicrete, BioAggregate and white ProRoot MTA (mineral trioxide aggregate) to prevent glucose leakage through root-end fillings. Methodology After root canal instrumentation, the apical 3 mm of maxillary incisors were resected and retropreparations, 3 mm in depth, were created with ultrasound. Root-end cavities were filled with the tested materials (15 roots per group). All roots were mounted in a double-chamber system to assess glucose penetration using 15 psi pressure application. After 1 h, glucose concentrations in the lower chamber were measured following an enzymatic reaction. Four roots were used as controls. One-way anova verified differences in glucose leakage between groups and Tukey test performed multiple comparisons. Significance was set at a = 5%. Results There was a significant difference between the three materials (anova, P < 0.05). Ceramicrete had significantly lower glucose penetration than BioAggregate (Tukey, P < 0.05). There was no difference between the two bioceramic cements and white MTA (P > 0.05). Conclusions Both endodontic bioceramic repair cements displayed similar leakage results to white MTA when used as root-end fillings materials. Ceramicrete had significantly lower glucose penetration.

Copper-zinc alloy coatings were deposited on mild steel substrates using sodium citrate electrolytes at room temperature and under direct current. For the bath composition studied, factorial design was used to verify the influence of deposition parameters, such as current density and mechanical stirring, on the cathodic efficiency, the contents of copper and zinc, and the amount of hydrogen evolution. Moreover, the four responses were simultaneously studied by using an optimization methodology. The results suggest that the optimum point for reaching good quality copper-zinc alloy deposits from the proposed citrate electrolytes are 29 A m -2 and 247 rpm for bath 3 and 13 A m -2 and 67 rpm for bath 4. Applying these conditions, a yellowreddish coating was obtained from bath 3, while a bright red deposit was produced from bath 4.