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Structural elucidation of triclinic and monoclinic SFCA-III - killing two birds with one stone.

ABSTRACT: A part of the system CaO-SiO2-Al2O3-Fe2O3-MgO which is of relevance to iron-ore sintering has been studied in detail. For a bulk composition corresponding to 10.45?wt% CaO, 5.49?wt% MgO, 69.15?wt% Fe2O3, 13.37?wt% Al2O3 and 1.55?wt% SiO2 synthesis runs have been performed in air in the range between 1100 and 1300°C. Products have been characterized using reflected-light microscopy, electron microprobe analysis and diffraction techniques. At 1250°C, an almost phase-pure material with composition Ca2.99Mg2.67Fe3+14.58Fe2+0.77Al4.56Si0.43O36 has been obtained. The compound corresponds to the first Si-containing representative of the M14+6nO20+8n polysomatic series of so-called SFCA phases (Silico-Ferrites of Calcium and Aluminum) with n = 2 and is denoted as SFCA-III. Single-crystal diffraction investigations using synchrotron radiation at the X06DA beamline of the Swiss Light Source revealed that the chemically homogenous sample contained both a triclinic and monoclinic polytype. Basic crystallographic data are as follows: triclinic form: a = 10.3279?(2)?Å, b = 10.4340?(2)?Å, c = 14.3794?(2)?Å, ? = 93.4888?(12)°, ? = 107.3209?(14)° and ? = 109.6626?(14)°, V = 1370.49?(5)?Å3, Z = 2, space group P{\overline 1}; monoclinic form: a = 10.3277?(2)?Å, b = 27.0134?(4)?Å, c = 10.4344?(2)?Å, ? = 109.668?(2)°, V = 2741.22?(9)?Å3, Z = 4, space group P21/n. Structure determination of both modifications was successful using diffraction data from the same allotwinned crystal. A description of the observed polytypism within the framework of OD-theory is presented. Triclinic and monoclinic SFCA-III actually correspond to the two possible maximum degree of order structures based on OD-layers containing three spinel (S) and one pyroxene (P) modules (?S3P?). The existence of SFCA-III in industrial iron-ore sinters has yet to be confirmed. Polytypism is likely to occur in other SFCA-members (SFCA, SFCA-I) relevant to sintering as well, but has so far been neglected in the characterization of industrial samples. Our results shed light on this phenomenon and may therefore be also helpful for better interpretation of the powder diffraction patterns that are used for phase analysis of iron-ore sinters.

SUBMITTER: Kahlenberg V

PROVIDER: S-EPMC6900907 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Structural elucidation of triclinic and monoclinic SFCA-III - killing two birds with one stone.

Kahlenberg Volker V Krüger Hannes H Goettgens Valerie Sue VS

Acta crystallographica Section B, Structural science, crystal engineering and materials 20191120 Pt 6

A part of the system CaO-SiO2-Al2O3-Fe2O3-MgO which is of relevance to iron-ore sintering has been studied in detail. For a bulk composition corresponding to 10.45 wt% CaO, 5.49 wt% MgO, 69.15 wt% Fe2O3, 13.37 wt% Al2O3 and 1.55 wt% SiO2 synthesis runs have been performed in air in the range between 1100 and 1300°C. Products have been characterized using reflected-light microscopy, elect ...[more]

PMID: 32830692

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Project description:Background and objectiveThe videofluoroscopic swallowing study (VFSS) is a gold-standard imaging technique for assessing swallowing, but analysis and rating of VFSS recordings is time consuming and requires specialized training and expertise. Researchers have recently demonstrated that it is possible to automatically detect the pharyngeal phase of swallowing and to localize the bolus in VFSS recordings via computer vision approaches, fostering the development of novel techniques for automatic VFSS analysis. However, training of algorithms to perform these tasks requires large amounts of annotated data that are seldom available. In this paper, we demonstrate that the challenges of pharyngeal phase detection and bolus localization can be solved together using a single approach.MethodsWe propose a deep-learning framework that jointly tackles pharyngeal phase detection and bolus localization in a weakly-supervised manner, requiring only the initial and final frames of the pharyngeal phase as ground truth annotations for the training. Our approach stems from the observation that bolus presence in the pharynx is the most prominent visual feature upon which to infer whether individual VFSS frames belong to the pharyngeal phase. We conducted extensive experiments with multiple convolutional neural networks (CNNs) on a dataset of 1245 bolus-level clips from 59 healthy subjects.ResultsWe demonstrated that the pharyngeal phase can be detected with an F1-score higher than 0.9. Moreover, by processing the class activation maps of the CNNs, we were able to localize the bolus with promising results, obtaining correlations with ground truth trajectories higher than 0.9, without any manual annotations of bolus location used for training purposes.ConclusionsOnce validated on a larger sample of participants with swallowing disorders, our framework will pave the way for the development of intelligent tools for VFSS analysis to support clinicians in swallowing assessment.

Dataset Information

Structural elucidation of triclinic and monoclinic SFCA-III - killing two birds with one stone.

Publications

Structural elucidation of triclinic and monoclinic SFCA-III - killing two birds with one stone.

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