Reconstructive surgery for oral cavity cancer

Treatment of patients with advanced oral cavity cancer remains challenging

Thermal history of diamond from Arkhangelskaya and Karpinsky-I kimberlite pipes

This work studies and compares the main morphological, structural, and mineralogical features of 350 diamond crystals from the Karpinsky-I and 300 crystals of the Arkhangelskaya kimberlite pipes. The share of crystals of octahedral habit together with individual crystals of transitional forms with sheaf-like and splintery striation is higher in the Arkhangelskaya pipe and makes 15 %. The share of cuboids and tetrahexahedroids is higher in the Karpinsky-I pipe and stands at 14 %. The share of dodecahedroids in the Arkhangelskaya and Karpinsky-I pipes are 60 % and 50 %, respectively. The indicator role of the nitrogen-vacancy N3 center active in absorption and luminescence is shown. Crystals with the N3 absorption system have predominantly octahedral habit or dissolution forms derived from the octahedra. Their thermal history is the most complex. Absorption bands of the lowest-temperature hydrogen-containing defects (3050, 3144, 3154, 3188, 3310 cm−1, 1388, 1407, 1432, 1456, 1465, 1503, 1551, 1563 cm−1), are typical for crystals without N3 system, where in the absorption spectra nitrogen is in the form of low-temperature A and C defects. The above mentioned bands are registered in the spectra of 16 % and 42 % of crystals from the Arkhangelskaya and Karpinsky-I pipes, respectively. The diamond of the studied deposits is unique in the minimum temperature (duration) of natural annealing. Based on a set of features, three populations of crystals were distinguished, differing in growth conditions, post-growth, and thermal histories. The established regularities prove the multi-stage formation of diamond deposits in the north of the East European Platform and significant differences from the diamonds of the Western Cisurals. The results suggest the possibility of the existence of primary deposits dominated by diamonds from one of the identified populations

Defects of diamond crystal structure as an indicator of crystallogenesis

Based on the study of a representative collections of diamonds from diamondiferous formations of the Urals and deposits of the Arkhangelsk and Yakutian diamond provinces, we established patterns of zonal and sectoral distribution of crystal structure defects in crystals of different morphological types, identified the specifics of crystals formed at different stages of crystallogenesis and performed a comprehensive analysis of constitutional and population diversity of diamonds in different formations. We identified three stages in the crystallogenesis cycle, which correspond to normal and tangential mechanisms of growth and the stage of changing crystal habit shape. At the stage of changing crystal habit shape, insufficient carbon supersaturation obstructs normal growth mechanism, and the facets develop from existing surfaces. Due to the absent stage of growth layer nucleation, formation of new {111} surfaces occurs much faster compared to tangential growth mechanism. This effect allows to explain the absence of cuboids with highly transformed nitrogen defects at the A-B1 stage: they have all been refaceted by a regenerative mechanism. Based on the revealed patterns, a model of diamond crystallogenesis was developed, which takes into account the regularities of growth evolution, thermal history and morphological diversity of the crystals. The model implies the possibility of a multiply repetitive crystallization cycle and the existence of an intermediate chamber; it allows to explain the sequence of changes in morphology and defect-impurity composition of crystals, as well as a combination of constitutional and population diversity of diamonds from different geological formations

Regeneration Growth as One of the Principal Stages of Diamond Crystallogenesis

Revealing the internal structure of diamonds is key to understanding the general regularities of crystal growth and dissolution. This paper presents and summarizes data on the internal structure of diamonds of different morphological types, colors and defect-impurity composition. In order to provide a comprehensive explanation of the stages of diamond growth, crystals and plates were observed, and panchromatic cathodoluminescence and photoluminescence techniques were applied. This article considers the mechanism of tangential growth from existing surfaces (regeneration growth) as an intermediate stage between normal and tangential crystal growth. The regeneration growth is very fast due to the absence of the limiting stage-nucleation of a new atomic layer. Cuboid diamonds were refaceted to stepped octahedrons by the regeneration growth mechanism. A schematic model of crystal habit transformation due to regeneration growth explains the internal structure of crystals in connection with their morphology and thermal history. The main variants of regeneration stage and its morphological manifestations were demonstrated. Most diamonds pass through the regeneration stage, and in many cases, it was a stage of growth termination

Regeneration Growth as One of the Principal Stages of Diamond Crystallogenesis

Revealing the internal structure of diamonds is key to understanding the general regularities of crystal growth and dissolution. This paper presents and summarizes data on the internal structure of diamonds of different morphological types, colors and defect-impurity composition. In order to provide a comprehensive explanation of the stages of diamond growth, crystals and plates were observed, and panchromatic cathodoluminescence and photoluminescence techniques were applied. This article considers the mechanism of tangential growth from existing surfaces (regeneration growth) as an intermediate stage between normal and tangential crystal growth. The regeneration growth is very fast due to the absence of the limiting stage-nucleation of a new atomic layer. Cuboid diamonds were refaceted to stepped octahedrons by the regeneration growth mechanism. A schematic model of crystal habit transformation due to regeneration growth explains the internal structure of crystals in connection with their morphology and thermal history. The main variants of regeneration stage and its morphological manifestations were demonstrated. Most diamonds pass through the regeneration stage, and in many cases, it was a stage of growth termination

Reconstructive surgery for oral cavity cancer

Treatment of patients with advanced oral cavity cancer remains challenging

Crystal structures and supramolecular features of 9,9-dimethyl-3,7-diazabicyclo[3.3.1]nonane-2,4,6,8-tetraone, 3,7-diazaspiro[bicyclo[3.3.1]nonane-9,1′-cyclopentane]-2,4,6,8-tetraone and 9-methyl-9-phenyl-3,7-diazabicyclo[3.3.1]nonane-2,4,6,8-tetraone dimethylformamide monosolvate

Compounds (I), C9H10N2O4, (II), C11H12N2O4, and (III), C14H12N2O4·C3H7NO represent 9,9-disubstituted-3,7-diazabicyclo[3.3.1]nonane-2,4,6,8-tetraone derivatives with very similar molecular geometries for the bicyclic framework: the dihedral angle between the planes of the imide groups is 74.87 (6), 73.86 (3) and 74.83 (6)° in (I)–(III), respectively. The dimethyl derivative (I) is positioned on a crystallographic twofold axis and its overall geometry deviates only slightly from idealized C2v symmetry. The spiro-cyclopentane derivative (II) and the phenyl/methyl analog (III) retain only internal Cs symmetry, which in the case of (II) coincides with crystallographic mirror symmetry. The cyclopentane moiety in (II) adopts an envelope conformation, with the spiro C atom deviating from the mean plane of the rest of the ring by 0.548 (2) Å. In compound (III), an N—H...O hydrogen bond is formed with the dimethylformamide solvent molecule. In the crystal, both (I) and (II) form similar zigzag hydrogen-bonded ribbons through double intermolecular N—H...O hydrogen bonds. However, whereas in (I) the ribbons are formed by two trans-arranged O=C—N—H amide fragments, the amide fragments are cis-positioned in (II). The formation of ribbons in (III) is apparently disrupted by participation of one of its N—H groups in hydrogen bonding with the solvent molecule. As a result, the molecules of (III) form zigzag chains rather than the ribbons through intermolecular N—H...O hydrogen bonds. The crystal of (I) was a pseudo-merohedral twin

Diphenylalanine-based microribbons for piezoelectric applications via inkjet printing

Peptide-based nanostructures are very promising for nanotechnological applications because of their excellent self-assembly properties, biological and chemical flexibility, and unique multifunctional performance. However, one of the limiting factors for the integration of peptide assemblies into functional devices is poor control of their alignment and other geometrical parameters required for device fabrication. In this work, we report a novel method for the controlled deposition of one of the representative self-assembled peptides - diphenylalanine (FF) - using a commercial inkjet printer. The initial FF solution, which has been shown to readily self-assemble into different structures such as nano- and microtubes and microrods, was modified to be used as an efficient ink for the printing of aligned FF-based structures. Furthermore, during the development of the suitable ink, we were able to produce a novel type of FF conformation with high piezoelectric response and excellent stability. By using this method, ribbonlike microcrystals based on FF could be formed and precisely patterned on different surfaces. Possible mechanisms of structure formation and piezoelectric effect in printed microribbons are discussed along with the possible applications

Ultrasonography of the larynx for diagnosis of the vocal folds mobility impairment

Purpose. To study a possibility of performance and diagnostic accuracy of ultrasonography (US) of a larynx in identification of motility disorders of VF (vocal folds) in comparison with the laryngoscope which is traditionally applied for this purpose. Materials and methods. According to the objectives of the study, two patient groups were formed. In first group of patients (n = 466) we studied acceptability of ultrasonografy to discriminate various laryngeal structures. In second group of patient (n = 432) we evaluated the diagnostic accuracy of ultrasonography in point of detection of vocal muscles paresis. Results. Laryngeal structures were available to examination by ultrasound (without taking in account age and sex) in 92.7% of patients. Two patterns have been identified in the course of this part of the study: deterioration of visibility of the vocal folds with increasing patient age and better visibility of the vocal folds in women than in men. According to the comparative analysis, ultrasonography accuracy rate (in those patients who had had clearly visible vocal folds during ultrasonography) did not differ from that during videolaryngoscopy. Conclusion. During the conducted research it was found that the US of the larynx is an effective and perspective method for detection of a paresis of VF with sensitivity and specificity 93,55% and 100% respectively. Among those patients whoapos; VF are available to ultrasound evaluation the accuracy of method is comparable with a videolaryngoscopy and can be used with success in daily work of units of endocrine surgery