Induced thermoluminescence study of experimentally shock-loaded oligoclase

Artificially induced thermoluminescence (TL) in oligoclase samples which were shock-loaded up to 27 GPa was measured. The essential increase of the TL sensitivity in relation to the total gamma-ray irradiation dose was observed only in samples at the 27 GPa pressure. This result can be explained by the initiation of additional radiation damages in the shocked oligoclace crystal lattice

Oxidation kinetics of Cr-coated zirconium alloy: Effect of coating thickness and microstructure

Cr coatings with the thickness of 4.5–9.0 μm and dense/columnar microstructure were deposited onto Zr alloy by cooled or hot target magnetron sputtering. Steam oxidation tests were performed under temperature ramp from 500 to 1200 °C and isothermal treatment at 900−1200 °C for 10−30 min. The measurements of mass gain showed different oxidation kinetics depending on microstructure and thickness of the as-deposited Cr coatings. The dense microstructure is favorable to prevent alloy oxidation as long as the Cr layer is intact. The higher activation energy of 202 kJ/mol is observed for the dense 4.5 μm-thick Cr coating while thicker columnar coatings have 177−183 kJ/mol. The time of transition from protective to non-protective behavior increases with coating thickness. It was shown that the 9 μm-thick Cr coating with columnar microstructure better protects the zirconium alloy from oxidation at 1200 °C for 10 min in comparison with thinner coatings. The fast interdiffusion of Cr and Zr at coating/alloy interface significantly affects the oxidation kinetics of Cr-coated zirconium alloy at temperatures above 1100 °C and long oxidation time

XANES Investigation of the Influence of a Coordinating Atomic Environment in Biomimetic Composite Materials

In our work, the influence of the coordination environment of the Ca atom states in biomimetic mineralizing composite dental materials integrated with dental tissue was investigated. Biomimetic composites as well as natural dental tissue samples were investigated using synchrotron X-ray absorption near edge structure (XANES) spectroscopy. Energy structure studies revealed a number of important features related to the different type of calcium atom environment. the surface of nanocrystalline calcium carbonate-substituted hydroxyapatite (nano-cHAp) crystals in natural enamel and dentin involved in the formation of bonds with the organic matrix is more characterized by the coordination environment of the calcium atom corresponding to its location in the CaI position, i.e. bound through common oxygen atoms with PO4 tetrahedrons. At the same time, on the surface of nano-cHAp crystals in bioinspired dental materials, the calcium atom is more characteristically located in the CaII position, bound to the hydroxyl OH group. The detected features in the coordination atomic environment in nano-cHAp play a fundamental role for engineering a biomimetic dental composite of the natural organomineral interaction in the mineralized tissue. © 2022 The Authors.This work was funded by the grant of Russian Science Foundation, grant number 21-75-10005. The access to scientific equipment and methodology was provided under support of the Ministry of Science and Higher Education of Russia, Agreement N 075-15-2021-1351

The Molecular and Mechanical Characteristics of Biomimetic Composite Dental Materials Composed of Nanocrystalline Hydroxyapatite and Light-Cured Adhesive

The application of biomimetic strategies and nanotechnologies (nanodentology) has led to numerous innovations and provided a considerable impetus by creating a new class of modern adhesion restoration materials, including different nanofillers. An analysis of the molecular properties of biomimetic adhesives was performed in this work to find the optimal composition that provides high polymerisation and mechanical hardness. Nanocrystalline carbonate-substituted calcium hydroxyapatite (nano-cHAp) was used as the filler of the light-cured adhesive Bis-GMA (bisphenol A-glycidyl methacrylate). The characteristics of this substance correspond to the apatite of human enamel and dentin, as well as to the biogenic source of calcium: avian eggshells. The introduction and distribution of nano-cHAp fillers in the adhesive matrix resulted in changes in chemical bonding, which were observed using Fourier transform infrared (FTIR) spectroscopy. As a result of the chemical bonding, the Vickers hardness (VH) and the degree of conversion under photopolymerisation of the nano-cHAp/Bis-GMA adhesive increased for the specified concentration of nanofiller. This result could contribute to the application of the developed biomimetic adhesives and the clinical success of restorations. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.075-15-2021-1351; Russian Science Foundation, RSF: 21-15-00026This work was funded by the grant of the Russian Science Foundation, grant number 21-15-00026. The access to scientific equipment and methodology was provided under the support of the Ministry of Science and Higher Education of Russia, Agreement No. 075-15-2021-1351

Effect of Exo/Endogenous Prophylaxis Dentifrice/Drug and Cariogenic Conditions of Patient on Molecular Property of Dental Biofilm: Synchrotron FTIR Spectroscopic Study

(1) Objectives: This study is the first one to investigate the molecular composition of the dental biofilm during the exogenous and endogenous prophylaxis stages (use of dentifrice/drug) of individuals with different cariogenic conditions using molecular spectroscopy methods. (2) Materials and Methods: The study involved 100 participants (50 males and 50 females), aged 18–25 years with different caries conditions. Biofilm samples were collected from the teeth surface of all participants. The molecular composition of biofilms was investigated using synchrotron infrared microspectroscopy. Changes in the molecular composition were studied through calculation and analysis of ratios between organic and mineral components of biofilm samples. (3) Results: Based on the data obtained by synchrotron FTIR, calculations of organic and mineral component ratios, and statistical analysis of the data, we were able to assess changes occurring in the molecular composition of the dental biofilm. Variations in the phosphate/protein/lipid, phosphate/mineral, and phospholipid/lipid ratios and the presence of statistically significant intra-and inter-group differences in these ratios indicate that the mechanisms of ion adsorption, compounds and complexes arriving from oral fluid into dental biofilm during exo/endogenous prophylaxis, differ for patients in norm and caries development. (4) Conclusions: The conformational environment and charge interaction in the microbiota and the electrostatic state of the biofilm protein network in patients with different cariogenic conditions play an important role. (5) Clinical Significance: Understanding the changes that occur in the molecular composition of the dental biofilm in different oral homeostasis conditions will enable successful transition to a personalised approach in dentistry and high-tech healthcare. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 21-15-00026; Ministry of Science and Higher Education of the Russian Federation: N 075-15-2021-1351This work was funded by the grant of Russian Science Foundation, grant number 21-15-00026. The access to scientific equipment and methodology was provided under support of the Ministry of Science and Higher Education of Russia, Agreement N 075-15-2021-1351