Dust remobilization in fusion plasmas under steady state conditions

The first combined experimental and theoretical studies of dust remobilization by plasma forces are reported. The main theoretical aspects of remobilization in fusion devices under steady state conditions are analyzed. In particular, the dominant role of adhesive forces is highlighted and generic remobilization conditions - direct lift-up, sliding, rolling - are formulated. A novel experimental technique is proposed, based on controlled adhesion of dust grains on tungsten samples combined with detailed mapping of the dust deposition profile prior and post plasma exposure. Proof-of-principle experiments in the TEXTOR tokamak and the EXTRAP-T2R reversed-field pinch are presented. The versatile environment of the linear device Pilot-PSI allowed for experiments with different magnetic field topologies and varying plasma conditions that were complemented with camera observations.Comment: 16 pages, 11 figures, 3 table

Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions

For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A^2\Delta - X^2\Pi Ger\"o band around 430 nm. The CH A-level can be excited either by electron-impact or by dissociative recombination (D.R.) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by D.R. dominates at T_e < 1.5 eV. The results indicate that the fraction of D.R. events that lead to a CH radical in the A-level and consequent photon emission is at least 10%. Additionally, quenching of the excited CH radicals by electron impact de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at n_e=1.3*10^20 m^-3, to 2.8 at n_e=9.3*10^20 m^-3. Its inclusion significantly improved agreement between experiment and modeling

Meta-Subject Approach to Study of Astronomy

The article discusses the issues of meta-subject approach in the study of astronomy as a design method for forming a worldview based on a scientific, philosophical and axiological understanding of phenomena and ideas. The components of the meta-subject approach, strategic decisions are revealed.В статье рассматриваются вопросы метапредметного подхода в изучении астрономии как проектного метода формирования мировоззрения на основе научного, философского и аксиологического осмысления явлений и идей. Раскрываются компоненты метапредметного подхода, стратегические решения

Ferroelectric nanocomposites based on polymer ferroelectrics and graphene/oxide graphene: Computer modeling and SPFM experiments

The authors are thankful to the Russian Science Foundation (RSF grant # 16-19-10112) and to the Russian Foundation for Basic Researches (RFBR grants # 16-51-53917) for support. Prof. Xiang-Jian Meng expresses his gratitude to the National Natural Science Foundation of China (NNSFC) for support of the project: "The study on the new type of infrared detector based on ferroelectric tunnel junction"

Temporomandibular Disorder and Cerebellopontine Angle Meningioma: Perspectives from Three Medical Specialists

Introduction. The relevance of the study is due to the complexity of the differential diagnosis of Kosten's syndrome and meningioma in the area of the cerebellar bridge angle of the brain, as well as the severe suffering of patientsThe purpose of our study: development of an algorithm for the approach to the differential diagnosis of meningioma of the cerebellar angle and Kosten's syndrome.Materials and methods. To accomplish the set tasks, we examined 22 patients who complained of headache, hearing impairment, sensation of tinnitus, pain and crepitus in the temporomandibular joint during movements of the lower jaw, paresthesia of the oral and nasal mucosa. All patients were assigned studies: cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI) of the TMJ according to indications.Results. Since complaints can lead patients to see doctors of various specialties, it is necessary to be able to differentiate between Costen's syndrome and a tumor of the cerebral pons-cerebral angle. In Costen's syndrome, the pain most often has an aching character, in contrast to the volumetric formations of the brain, in which the pain is burning, spreading along the branches of the facial or trigeminal nerve. One of the main methods of excluding a brain tumor is magnetic resonance imaging.Conclusions. The most significant modern method for diagnosing Costen's syndrome and meningioma of the cerebellopontine angle is magnetic resonance imaging (MRI) of the TMJ and the brain. Differential signs of Costen's syndrome are distal displacement of the head of the lower jaw, diagnosed by CBCT and MRI, as well as displacement of the articular disc (determined by MRI). A meningioma of the cerebellopontine angle is indicated by the burning nature of pain in half of the face, as well as confirmation of the diagnosis by magnetic resonance imaging of the brain

Modeling of Self-Assembled Peptide Nanotubes and Determination of Their Chirality Sign Based on Dipole Moment Calculations

The chirality quantification is of great importance in structural biology, where the differ-ences in proteins twisting can provide essentially different physiological effects. However, this aspect of the chirality is still poorly studied for helix-like supramolecular structures. In this work, a method for chirality quantification based on the calculation of scalar triple products of dipole moments is suggested. As a model structure, self-assembled nanotubes of diphenylalanine (FF) made of L-and D-enantiomers were considered. The dipole moments of FF molecules were calculated using semi-empirical quantum-chemical method PM3 and the Amber force field method. The obtained results do not depend on the used simulation and calculation method, and show that the D-FF nanotubes are twisted tighter than L-FF. Moreover, the type of chirality of the helix-like nanotube is opposite to that of the initial individual molecule that is in line with the chirality alternation rule general for different levels of hierarchical organization of molecular systems. The proposed method can be applied to study other helix-like supramolecular structures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgments: The authors are grateful to the Russian Foundation for Basic Researches (RFBR): grants №№ 19–01–00519_A and 20-51-53014_GFEN_A. Part of this work (A.K.) was supported by the Ministry of Science and Higher Education of the Russian Federation (grant No. 075-15-2021-588). P.Z., S.K. and A.K. are grateful to the FCT project “BioPiezo”—PTDC/CTM−CTM/31679/2017 (CENTRO-01-0145-FEDER-031679) and to the project CICECO-Aveiro Institute of Materials, refs. UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. Part of this work was funded by national funds (OE), through FCT–Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. A.S. and E.M. are grateful to the the Interdisciplinary Scientific and Educational School of Moscow University “Fundamental and Applied Space Research”

Crystal structure and growth kinetics of self-assembled microtubes with different chirality

The measurements of microtubes growth kinetics and morphology analysis were done in Ural Federal University (UrFU) and made possible by Russian Science Foundation (Grant No. 18-72-00052). The equipment of the Ural Center for Shared Use “Modern nanotechnology” UrFU was used. Computer simulation was performed under the support of Russian Foundation for Basic Research (Grant No. 19-01-00519 А). X-ray diffraction data were collected under the experiment SC-4587 at the European Synchrotron Radiation Source (ESRF, Grenoble, France). S.K., P.Z., L.M. and A.K. are grateful to FCT project PTDC/CTM-CTM/31679/2017. P.Z. and L.M. are grateful to FCT project PTDC/QEQ-QAN/6373/2014. S.K and A.K were also supported by the joint Portugal-Turkey project (TUBITAK/0006/2014). Part of this work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES

Electrospinning piezoelectric fibers for biocompatible devices

The field of nanotechnology has been gaining great success due to its potential in developing new generations of nanoscale materials with unprecedented properties and enhanced biological responses. This is particularly exciting using nanofibers, as their mechanical and topographic characteristics can approach those found in naturally occurring biological materials. Electrospinning is a key technique to manufacture ultrafine fibers and fiber meshes with multifunctional features, such as piezoelectricity, to be available on a smaller length scale, thus comparable to subcellular scale, which makes their use increasingly appealing for biomedical applications. These include biocompatible fiber-based devices as smart scaffolds, biosensors, energy harvesters, and nanogenerators for the human body. This paper provides a comprehensive review of current studies focused on the fabrication of ultrafine polymeric and ceramic piezoelectric fibers specifically designed for, or with the potential to be translated toward, biomedical applications. It provides an applicative and technical overview of the biocompatible piezoelectric fibers, with actual and potential applications, an understanding of the electrospinning process, and the properties of nanostructured fibrous materials, including the available modeling approaches. Ultimately, this review aims at enabling a future vision on the impact of these nanomaterials as stimuli-responsive devices in the human body