Spectroscopic signature of the pathological processes of carious dentine based on FTIR investigations of the oral biological fluids

The aim of our work is to find a spectroscopic signature of the pathological processes of carious dentine based on the investigations of the molecular composition of the oral biological fluids with the use of FTIR synchrotron techniques. This complex analysis of the obtained data shows that a number of signatures are present only in the spectra of dentine and gingival fluids from the patients developing caries of the deep dentine tissues. The detected features and complex analysis of the quantitative and qualitative data representing signatures of the development of oral cavity pathologies can enhance the quality of dental screening. © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Engineering of a biomimetic interface between a native dental tissue and restorative composite and its study using synchrotron ftir microscopic mapping

The aim of this work is to develop a biomimetic interface between the natural tooth tissue and the restorative composite and to study it on the basis of synchrotron micro-FTIR mapping and multidimensional processing of the spectral data array. Using hierarchical cluster analysis of 3D FTIR data revealed marked improvements in the formation of the dentine/adhesive/dental hybrid interface using a biomimetic approach. The use of a biomimetic strategy (application of an amino acid– modified primer, alkaline calcium and a nano-c-HAp–modified adhesive) allowed the formation of a matrix that can be structurally integrated with natural dentine and dental composite. The biomimetic hybrid layer was characterised by homogeneous chemical composition and a higher degree of conversion of the adhesive during polymerisation, which should provide optimal integration of the dental composite with the dentine. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work was supported by the grant of Russian Science Foundation, grant number 21-15-00026

Mechanism of interaction among nanocrystalline carbonate-substituted hydroxyapatite and polar amino-acids for the biomimetic composite technology: Spectroscopic and structural study

This study investigated changes in the interaction of B-type non-stoichiometric nanocrystalline carbonate-substituted hydroxyapatite (nano-CHAP) with polar amino acids (AA) with respect to CHAP-AA linking. Molecular vibrational spectroscopy revealed for the first time that the surface interaction of polar amino acids with defective nano-CHAP is determined not only by the charge state of AA but can be mediated by a foreign ion conjugated with the lateral bonds of amino acids. Understanding this mechanism of CHAP-AA interaction is required for the development of the new generation of dental biomimetic materials based on HAP as well as for their qualitative integration with the amino acid matrix of the dental tissues. © 2020Russian Foundation for Basic Research, RFBR: MK-419.2019.2, 18-29-11008The study was performed under support of Russian Foundation for Basic Research (RFBR) grant №18-29-11008 mk and grant of the President of Russian Federation №MK-419.2019.2

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

Случай первичной солитарной плазмоцитомы трахеи

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Development of a new approach to diagnosis of the early fluorosis forms by means of FTIR and Raman microspectroscopy

This study is aimed at investigating the features of mineralization of the enamel apatite at initial stages of fluorosis development. Samples of teeth with intact and fluorotic enamel in an early stage of the disease development (Thylstrup–Fejerskov Index = 1–3) were studied by Raman scattering and FTIR using Infrared Microspectroscopy beamline at Australian Synchrotron equipment. Based on the data obtained by optical microspectroscopy and calculation of the coefficient R [A-type/B-type], which represents the ratio of carbonation fraction of CO32−, replacing phosphate or hydroxyl radicals in the enamel apatite lattice, the features of mineralization of enamel apatite in the initial stages of development of the pathology caused by an increased content of fluorine in the oral cavity were established. Statistical analysis of the data showed significant differences in the mean values of R [A-type/B-type] ratio between the control and experimental groups for surface layers (p < 0.01). The data obtained are potentially significant as benchmarks in the development of a new approach to preventive diagnostics of the development of initial and clinically unregistered stages of human teeth fluorosis, as well as personalized control of the use of fluoride-containing caries-preventive agents. © 2020, The Author(s).This work was supported by the grant of Russian Science Foundation, Grant Number 16–15-00003

Optical and structural properties of the GaAs heterostructures grown using AlGaAs superlattice buffer layer on compliant Si(100) substrates with the preformed porous-Si (por-Si) layer

360 nm and 700 nm thick GaAs layers were grown by MO MOCVD growth technique directly on compliant Si (100) substrate and on supper-lattice (SL) AlGaAs buffer layer. The XRD study revealed better structural quality for the sample grown on SL / por-Si buffer. AFM study revealed a smoother sample surface with blocks of more regular rectangular shape and larger size as well. Photoluminescence spectra of the samples revealed an energy shift of PL maximum intensity for both samples. Sample grown on SL buffer also showed higher PL intensity corresponding to better crystalline perfection

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

MicroRaman Study of Nanostructured Ultra-Thin AlGaN/GaN Thin Films Grown on Hybrid Compliant SiC/Por-Si Substrates

In our study, for the first time we demonstrate the advantages of using a compliant hybrid substrate of porSi/SiC to grow high-quality ultra-thin nanostructured AlxGa1−xN/GaN heterostructures using molecular beam epitaxy with plasma-activated nitrogen. Comparison of our experimental results obtained by micro-Raman spectroscopy, deconvolution, and the fitting of the experimental Raman spectra and subsequent calculations with information from already established literature sources show that the use of such a hybrid SiC/porSi substrate has a number of undeniable advantages for the growth of ultra-thin AlxGa1−xN/GaN nanoheterostructures without requiring the use of thick AIIIN buffer layers. Direct growth on a hybrid compliant substrate of SiC/porSi leads to a substantial relaxation in the elastic stresses between the epitaxial film, porous silicon, and silicon carbide, which consequently affects the structural quality of the ultra-thin AlxGa1−xN/GaN epitaxial layers. The experimental and computational data obtained in our work are important for understanding the physics and technology of AlxGa1−xN/GaN nanoheterostructures and will contribute to their potential applications in optoelectronics. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Russian Federation, Minobrnauka: FSRM-2020-0008, FZGU-2020-0036; Russian Science Foundation, RSF; Ministry of Science and Higher Education of the Russian Federation: 075-15-2021-1351Funding: This work was funded by grant no. 19-72-10007 from the Russian Science Foundation. The work of P.S. and A.M. was supported by the Ministry of Education and Science of the Russian Federation (grant No. FZGU-2020-0036 and No. FSRM-2020-0008). As a part of access to scientific equipment and methodology, this study was supported by the Ministry of Science and Higher Education of Russia under Agreement No. 075-15-2021-1351

HRXRD study of the effect of a nanoporous silicon layer on the epitaxial growth quality of GaN layer on the templates of SiC/por-Si/c-Si

Using High Resolution X-ray Diffraction (HRXRD) diagnostic techniques the influence of the transition layer of nanoporous silicon on the practical implementation and certain features of the epitaxial growth of GaN layers with the use of molecular beam epitaxy were investigated by means of plasma activation of nitrogen (MBE PA) on the templates of SiC/por-Si/c-Si. For the first time it was shown that introducing of the transition layer of nanoporous silicon in the template of SiC/por-Si/c-Si where the layer of 3C-SiC was obtained by substitution of the atoms had a number of indisputable advantages as compared with conventional silicon substrates. Particularly, such an approach, in fact, enabled a 90% reduction in the level of stresses in the crystalline lattice of the epitaxial GaN layer which was synthesized on SiC surface of SiC/por-Si/c-Si template by means of MBE PA technique as well as to decrease some of vertical dislocations within GaN layer. © 2020 The AuthorsRussian Science Foundation, RSFThe work was executed under support of the grant of Russian Science Foundation 19-72-10007 . Access to KNMF equipment was obtained under the grant of the President of the Russian Federation MD-42.2019.2