The mineralization-front theory is historically rooted in mineralization research fields for many decades. This theory is widely used to describe mineralization events in both osteogenesis and dentinogenesis. However, this model does not provide enough evidence to explain how minerals are propagated from the pulp-end dentin to dentin-enamel junction (DEJ). To address this issue, we modified the current research approaches by a) extending the mineral deposition windows of time from minutes to hours, instead of limiting the mineralization assay on days and weeks only; b) switching a regular fluorescent microscope to a more powerful confocal microscope; in which both mineral deposition rates and detail mineral labeling along with dentin tubules can be documented; and c) using reporter mice, including the Gli1-CreERT2 activated tomato and the 2.3 Col1-GFP to mark odontoblast processes combined with mineral dye injections. Our key findings are: 1) Odontoblast-processes, full of numerous mini-branches, evenly spread to entire dentin matrices with a high density of processes and a large diameter of the main process at the predentin-dentin junction; and 2) The minerals deposit along with entire odontoblast-processes and form many individual mineral collars surrounding odontoblast processes. As a result, these merged collars give rise to a single labeled line at the dentin-predentin junction, in which the dental tubules are wider in diameter and denser in odontoblast processes compared to other dentin areas. We therefore propose that it is the odontoblast-process that directly contributes to mineralization, which is not simply limited in the mineralization front at the edge of dentin and predentin, but occurs along with the entire odontoblast process. These new findings will shed new light on our understanding of dentin structure and function, as well as the mechanisms of mineralization.

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The authors demonstrate that energetic argon ions introduce phase transformation of a diamond- like carbon film. Inside an ultrahigh vacuum chamber, energetic Ar ions of 5keV were generated using an x-ray photon spectroscopy. After ion bombardment, x-ray photon spectroscopy (XPS) and friction tests were conducted in situ. The ex situ surface morphological analysis using an atomic force microscope and the multiple-peaks deconvolution of the C 1s XPS peak indicate that the changing ratio of sp2 and sp3 hybridization of carbon dominates the film friction. The authors conclude that the friction of the diamon dlike carbon film against itself depends on the carbon phase, not on the film surface roughness.

A novel method for the production of important medical radioisotopes has been developed. The approach is based on performing the nuclear reaction in inverse kinematics, namely sending a heavy-ion beam of appropriate energy on a light target (e.g. H, d, He) and collecting the isotope of interest. In this work, as a proof-of-concept, we studied the production of the theranostic radionuclide 67 Cu (T 1/2 =62 h) via the reaction of a 70 Zn beam at 15 MeV/nucleon with a hydrogen gas target. The 67 Cu radionuclide, alongside other coproduced isotopes, was collected after the gas target on an Al catcher foil and their radioactivity was measured by offline γ-ray analysis. After 36 h from the end of the irradiation, apart from the product of interest 67 Cu, the main radioimpurity coming from the 70 Zn+p reaction was 69m Zn (T 1/2 =13.8 h) that can be reduced by further radio-cooling. Moreover, along with the radionuclide of interest produced in inverse kinematics, the production of additional radioisotopes is possible by making use of the forward-focused neutrons from the reaction and letting them interact with a secondary target. A preliminary successful test of this concept was realized in the present study. The main requirement to obtain activities appropriate for preclinical studies is the development of high-intensity heavy-ion primary beams.

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