Lunar-like silicate material forms the Earth quasi-satellite (469219) 2016 HO3 Kamoʻoalewa

Little is known about Earth quasi-satellites, a class of near-Earth small solar system bodies that orbit the sun but remain close to the Earth, because they are faint and difficult to observe. Here we use the Large Binocular Telescope (LBT) and the Lowell Discovery Telescope (LDT) to conduct a comprehensive physical characterization of quasi-satellite (469219) Kamoʻoalewa and assess its affinity with other groups of near-Earth objects. We find that (469219) Kamoʻoalewa rotates with a period of 28.3 (+1.8/−1.3) minutes and displays a reddened reflectance spectrum from 0.4–2.2 microns. This spectrum is indicative of a silicate-based composition, but with reddening beyond what is typically seen amongst asteroids in the inner solar system. We compare the spectrum to those of several material analogs and conclude that the best match is with lunar-like silicates. This interpretation implies extensive space weathering and raises the prospect that Kamo’oalewa could comprise lunar material.

Effect of Irrigating Agitation after Root End Preparation on the Wall Cleaning and Bond Strength of Calcium Silicate Material in Retrograde Obturation

Objective The study aimed to evaluate the cleaning efficacy of irrigant activation with a new ultrasonic tip in root-end preparations and to determine its influence on the bond strength of calcium silicate-based material. Materials and Methods Maxillary canines were prepared and filled, and their root ends resected. Root-end cavities were ultrasonically prepared and randomly distributed into four groups according to the final irrigation protocols: G1 (ultrasonic irrigation [UI] + saline solution [SS]), G2 (syringe irrigation [SI] + SS), G3 (UI + ethylenediaminetetraacetic acid [EDTA]), and G4 (SI + EDTA). Cleaning efficacy analysis employed 72 specimens (n = 18) split longitudinally for imaging of the same areas by scanning electron microscopy (SEM). The percentage of dentinal tubules opened before and after irrigation was used as evaluation parameter. Push-out testing employed 40 specimens (n = 10) sectioned apical region perpendicularly, which slice was placed on a testing machine for the bond strength measurement and failure mode was assessed by SEM. The data were statistically analyzed (α ≤ 0.05). Results G3 (UI + EDTA) removed the smear layer more effectively, showed the best tubule opening (p < 0.05), and presented the highest mean bond strength values (p < 0.05). Failure modes were predominantly adhesive, except for the G3 (UI + EDTA) group, in which they were mainly mixed (80%). Conclusion The results of this study suggest that EDTA 17% agitation promoted better cleaning and smear layer removal, improving the push-out bond strength of calcium silicate material in retrograde obturation.

New Improved Thermoluminescence Magnesium Silicate Material for Clinical Dosimetry

Magnesium silicate has been prepared by a precipitation technique. This composite structure was proven by different tools, XRD, TGA&DTA, FTIR, and XRF. Magnesium silicate was found to have the formulas Mg1.1SiO3.2.1.1H2O. Thermoluminescence (TL) dosimetric properties like (linearity, fading, energy independence) of magnesium silicate in the shape of MgSiO3 have been estimated. A strong TL dosimetry peak associated with gamma radiation arises from 137Cs was developed. Different doses from gamma radiation were measured by thermoluminescence (TL) detection technique for magnesium silicate glasses in unique magnesium elements concentration to assess its dosimetric properties. A single strong peak of about 230 °C arises for all irradiated samples. Total integral values of TL output and TL of the principal peak values showing a linear behavior start with 0.5 Gray up to 2 Gray dose range. Correlation of magnesium silicate TL response and different doses showed dose-response improvement concerning low doses linear relationship.