Metallurgical Tests in Endodontics: A Narrative Review

Since there are no reviews of the literature on this theme, the aim of this narrative review is to summarize the metallurgical tests used in endodontics, pointing out their functional use and their pros and cons and giving readers a user-friendly guide to serve as an orientation aid in the plethora of metallurgical tests. With this purpose, a literature search for articles published between January 2001 and December 2021 was conducted, using the electronic database PubMed to collect all published articles regarding the metallurgical tests used in endodontics for the evaluation of NiTi rotary instruments. The search was conducted using the following keywords: “metallurgy”, “differential scanning calorimetry” (DSC), “X-ray diffraction” (XRD), “atomic force microscopy” (AFM), “energy-dispersive X-ray spectroscopy” (EDS), “focused ion beam analysis” (FIB) and “Auger electron spectroscopy” (AES) combined with the term “endodontics” or “NiTi rotary instruments”. Considering the inclusion and exclusion criteria, of the 248 articles found, only 81 were included in the narrative review. According to the results, more than 50% of the selected articles were published in one of the two most relevant journals in endodontics: International Endodontic Journal (22.2%) and Journal of Endodontics (29.6%). The most popular metallurgical test was DSC, with 43 related articles, followed by EDS (33 articles), AFM (22 articles) and XRD (21 articles). Few studies were conducted using other tests such as FIB (2 articles), micro-Raman spectroscopy (4 articles), metallographic analysis (7 articles) and Auger electron spectroscopy (2 articles).

Auger electron angular distributions following excitation or ionization from the Xe 3d and F 1s levels in xenon difluoride

Electron spectroscopy following Xe 3d and F 1s ionization in XeF2 elucidates the influence of core electrons on molecular bonding.

Электронная структура вариантов составов скандатных и оксидно-никелевых катодов СВЧ приборов

By methods of electron spectroscopy for chemical analysis and spectroscopy of characteristic losses of electron energy, the electronic structure of barium oxide crystallites doped with other chemical elements, including scandium from scandium-containing phases, was investigated. The physical and physicochemical conditions are formulated, the fulfillment of which allows to form the electronic structure of the scandate cathode with a high level of thermionic emission: the achievement of the minimum ratio of the surface volume concentration of oxygen vacancies and the maximum distance between the top of the valence band and the Fermi level.

Поверхностное соединение при адсорбции Be на W(100): определение абсолютной концентрации и свойства

Be adsorption and T = 900 - 1100 K results in formation of a stable adsorption state; it drops the activation energy of atomic Be dissolution in the substrate bulk, and all newly deposited Be dissolves in the substrate. The absolute concentration of atomic Be has been measured by Auger electron spectroscopy using specially designed ultra high vacuum getter Be source. The concentration is (1 ± 0.1)•1015 сm-2 , and corresponds to WBe stoichiometry relative to W surface concentration. The layer is destroyed at T > 1100 K, the atomic Be dissolves in the bulk with the activation energy ~ 3,5 eV.

Adducts of Lower Fullerenes and Amino Acids: Synthesis, Identification, and Quantum-Mechanical Modeling of Their Physicochemical Properties

Different ways of synthesizing bis-, tris-, and octakis-adducts of C60 and C70 lower fullerenes are considered, and their yield and purity are described. The adducts are identified by physicochemical means: elemental analysis, IR, electron spectroscopy, Raman spectroscopy, HPLC, mass spectrometry, and complex thermal analysis. Their physicochemical properties are modeled using computers, density functional theory, and molecular dynamics at the atomic-molecular level.

Migration of Excitation Energy in Furocoumarins

The migration of excitation energy of a number of psoralen compounds has been studied. For this, the methods of induced absorption spectroscopy, stationary electron spectroscopy, fluorescence and phosphorescence, as well as quantum chemistry were used. A comparative photostability of psoralen was achieved by exposure to a XeCl excilamp irradiation (emission wavelength λem = 308 nm) with parameters Δλ = 5–10 nm, Wpeak = 18 mW/cm2, p = 8.1 J/cm3, f = 200 kHz, pulse duration 1 μs. It was found that the singlet-triplet transition played a major role in the migration of excitation energy into triplet states. Among all tested compounds, substances with an OCH3-group in the structure have the strongest effect on the spectral-luminescent characteristics.

A practical method for determining film thickness using X-ray absorption spectroscopy in total electron yield mode

Thin films formed on surfaces have a large impact on the properties of materials and devices. In this study, a method is proposed using X-ray absorption spectroscopy to derive the film thickness of a thin film formed on a substrate using the spectral separation and logarithmic equation, which is a modified version of the formula used in electron spectroscopy. In the equation, the decay length in X-ray absorption spectroscopy is longer than in electron spectroscopy due to a cascade of inelastic scattering of electrons generated in a solid. The modification factor, representing a multiple of the decay length, was experimentally determined using oxidized Si and Cu with films of thickness 19 nm and 39 nm, respectively. The validity of the proposed method was verified, and the results indicated that the method can be used in the analysis of various materials with thin films.