Testing the reliability of the JEOL FEGSEM 6500F electron microprobe for quantitative major element analysis of glass shards from rhyolitic tephra.

Electronprobe microanalysis is now widely adopted in tephra studies as a technique for determining the major element geochemistry of individual glass shards. Accurate geochemical characterization is crucial for enabling robust tephra-based correlations; such information may also be used to link the tephra to a specific source and often to a particular eruption. In this article, we present major element analyses for rhyolitic natural glass standards analysed on three different microprobes and the new JEOL FEGSEM 6500F microprobe at Queen’s University Belfast. Despite the scatter in some elements, good comparability is demonstrated among data yielded from this new system, the previous Belfast JEOL-733 Superprobe, the JEOL-8200 Superprobe (Copenhagen) and the existing long-established microprobe facility in Edinburgh. Importantly, our results show that major elements analysed using different microprobes and variable operating conditions allow two high-silica glasses to be discriminated accurately.

Fixed-dose combination therapy for type 2 diabetes: sitagliptin plus pioglitazone

Importance of the field: Type 2 diabetes is typically associated with insulin resistance and dysfunction of insulin-secreting pancreatic beta-cells. Addressing these defects often requires therapy with a combination of differently acting antidiabetic agents. A potential novel combination in development brings together the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin with the thiazolidinedione pioglitazone into a fixed-dose single-tablet combination. The former component acts mainly to increase prandial insulin secretion; the latter improves insulin sensitivity.

Quantification of all-ceramic crown margin surface profile from try-in to 1-week post-cementation

To use profilometry to assess the margin surface profile of all-ceramic crowns (ACC’s) at try-in and 1-week after cementation with dual-cured resin (DC, RelyX ARC, 3 M ESPE, St. Paul, MN, USA), self-adhesive dual-cured resin (SADC, RelyX Unicem, 3 M ESPE), light-cured resin (LC, RelyX Veneer, 3 M ESPE) or chemically cured resin-modified glass ionomer (RMGI, RelyX Luting Plus, 3 M ESPE) luting cement. Methods: Forty, sound, extracted, human, premolar teeth underwent a standardised preparation for ACC’s. IPS Empress (Ivoclar-Vivadent, Liechtenstein) crowns of standard dimensions were fabricated and 10 luted with each cement and stored in water for 7 days. Three groups of serial profiles were taken, the first of the tooth preparation, the second of the crown margins at try-in and lastly of the crown margins after cementation and 7 days water storage. Results: There were no significant differences in the crown margin surface profile between the four cement groups at try-in. The change in crown margin position between try-in and post-cementation was significantly greater for DC than for LC and RMGI. SADC was not significantly different to the other cements. There were no significant differences in the crown margin extensions between the four cement groups, however most of the IPS Empress ACC’s in this study were underextended but this was not statistically significant. Conclusions: IPS Empress ACC’s seated more fully with LC and RMGI than with DC cement