Electron Inertial Effects on Rapid Energy Redistribution at Magnetic X-points

The evolution of non-potential perturbations to a current-free magnetic X-point configuration is studied, taking into account electron inertial effects as well as resistivity. Electron inertia is shown to have a negligible effect on the evolution of the system whenever the collisionless skin depth is less than the resistive scale length. Non-potential magnetic field energy in this resistive MHD limit initially reaches equipartition with flow energy, in accordance with ideal MHD, and is then dissipated extremely rapidly, on an Alfvenic timescale that is essentially independent of Lundquist number. In agreement with resistive MHD results obtained by previous authors, the magnetic field energy and kinetic energy are then observed to decay on a longer timescale and exhibit oscillatory behavior, reflecting the existence of discrete normal modes with finite real frequency. When the collisionless skin depth exceeds the resistive scale length, the system again evolves initially according to ideal MHD. At the end of this ideal phase, the field energy decays typically on an Alfvenic timescale, while the kinetic energy (which is equally partitioned between ions and electrons in this case) is dissipated on the electron collision timescale. The oscillatory decay in the energy observed in the resistive case is absent, but short wavelength structures appear in the field and velocity profiles, suggesting the possibility of particle acceleration in oppositely-directed current channels. The model provides a possible framework for interpreting observations of energy release and particle acceleration on timescales down to less than a second in the impulsive phase of solar flares.Comment: 30 pages, 8 figure

Durability of self-compacting concretes made with the natural pozzolan and siliceous fines

The effect of natural pozzolan and local waste siliceous fines on the durability of SCC was studied in this paper. Three self-compacting concretes were made with the following three additions, namely limestone fillers (SCC LF), pozzolanic fillers (SCC NP) and siliceous fillers (SCC SF). Durability tests, such as the porosity accessible to water, capillarity, carbonation, permeability to oxygen gas and diffusion of chloride ions, were carried out on these concretes in order to study the influence of these fillers on the transfer properties and durability of SCCs. The results obtained indicate that the SCC LF and SCC NP generally have the same transfer properties; these properties are significantly influenced by porosity and carbonation. In addition, the capillarity is nearly similar for all three SCCs. Moreover, it is worth noting that SCC NP gives permeability and diffusion coefficients of chloride ions slightly lower in comparison with those of the other SCCs. These finding suggest that the incorporation of Algerian natural fines and industrial waste as mineral additions into the SCC may have a positive environmental impact and can promote the development of local materials that are available in large quantities and whose production cost is low

Durability of self-compacting concretes made with the natural pozzolan and siliceous fines

The effect of natural pozzolan and local waste siliceous fines on the durability of SCC was studied in this paper. Three self-compacting concretes were made with the following three additions, namely limestone fillers (SCC LF), pozzolanic fillers (SCC NP) and siliceous fillers (SCC SF). Durability tests, such as the porosity accessible to water, capillarity, carbonation, permeability to oxygen gas and diffusion of chloride ions, were carried out on these concretes in order to study the influence of these fillers on the transfer properties and durability of SCCs. The results obtained indicate that the SCC LF and SCC NP generally have the same transfer properties; these properties are significantly influenced by porosity and carbonation. In addition, the capillarity is nearly similar for all three SCCs. Moreover, it is worth noting that SCC NP gives permeability and diffusion coefficients of chloride ions slightly lower in comparison with those of the other SCCs. These finding suggest that the incorporation of Algerian natural fines and industrial waste as mineral additions into the SCC may have a positive environmental impact and can promote the development of local materials that are available in large quantities and whose production cost is low

Authentication and authorisation in entrusted unions

This paper reports on the status of a project whose aim is to implement and demonstrate in a real-life environment an integrated eAuthentication and eAuthorisation framework to enable trusted collaborations and delivery of services across different organisational/governmental jurisdictions. This aim will be achieved by designing a framework with assurance of claims, trust indicators, policy enforcement mechanisms and processing under encryption to address the security and confidentiality requirements of large distributed infrastructures. The framework supports collaborative secure distributed storage, secure data processing and management in both the cloud and offline scenarios and is intended to be deployed and tested in two pilot studies in two different domains, viz, Bio-security incident management and Ambient Assisted Living (eHealth). Interim results in terms of security requirements, privacy preserving authentication, and authorisation are reported

Synthesis, crystal structures, Hirshfeld surface analysis and physico-chemical characterization of two new ZnII and CdII halidometallates

Two new organic–inorganic hybrid materials, based on 1, 3-CycloHexaneBis-(Methyl Amine), abbreviated CHBMA, namely (H2CHBMA)ZnCl4·2H2O (CP1) and (H2CHBMA)CdI4·2H2O (CP2), have been synthesized under mild conditions in acidic media and characterized by single-crystal X-ray diffraction, spectroscopic techniques (13C NMR, FTIR, RAMAN) and thermal analysis. The crystal structures of the two compounds were solved by single-crystal X-ray diffraction methods. Both compounds show a 3-dimensional supramolecular structure directed by various interactions between tetrahalidometallate anions (ZnCl42-, CdI42-), water molecule and organic cations (H2CHBMA)2+. For both compounds, the cyclohexane ring of the template cation is in a chair conformation with the methylammonium substituent in the equatorial positions and the two terminal ammonium groups in a cis conformation but with two different orientations (upward for CP1 and downward for CP2) which influences the supramolecular architecture of the two structures. Hirshfeld surface analysis and the associated two-dimensional finger print plots were used to explore and quantify the intermolecular interactions in the crystals

The ART of performance: engaging young people with assisted reproductive technologies

More children than ever before are conceived with the use of assisted reproductive technologies and many are raised in families that are structurally different from most. Research on the experiences of children growing up in diverse families has shown that children may face disapproval, a lack of understanding, and in some cases, bullying by those outside of their home environment, including from their peers at school This study evaluated the use of theatrical performance and post-performance discussions as a method of informing young people about different families. Findings indicated that performance was an effective and engaging learning tool, as it presented first-hand experiences of family diversity. Post-performance discussions were important in enabling young people to improve their understanding of different methods of Assisted Reproductive Technologies and diverse family forms. Young people were found to value engagement activities that are unbiased, interactive, and do not make them feel awkward or uncomfortable

Characterization of in-situ Doped Polycrystalline Silicon Using Schottky Diodes and Admittance Spectroscopy

In this work, Schottky Au-Polycrystalline silicon diodes are successfully realised. The barrier height is around ФB = 0.74 eV as determined from Capacitance – Bias (C-V) characteristics. The depth profile of the apparent doping is deduced from these measurements. Its behaviour leads to the experimental profile. Moreover, the diode admittance measurements versus the frequency and the temperature at different biases show the possibility to use this device to characterise the electrical quality of the polycrystalline silicon

Significance of the E-W fault system in the geodynamic evolution of the Tunisian Alpine Chain foreland. Example of the Sbiba-Cherichira fault system in central Tunisia

En Tunisie centrale, les bassins mio-plio-quaternaires de Sbiba et de Haffouz sont constitués de dépocentres délimités par des failles de direction proche de E-W, NW-SE, N070 o et N-S. Ces accidents bordiers bien identifiés en sub-surface et dont l’activité a été démontrée aux époques éo-crétacées, ont évolué durant le Néogène et le Quaternaire dans un système de décrochements en relais, alliant des structures compressives (plis N040 o à N080 o E, failles inverses, chevauchements…) et des structures distensives correspondant à des grabens et demi-grabens orientés E-W et N120 o à N150 o E. La région a été affectée du Néogène au Quaternaire inférieur par une succession de régimes tectoniques compressifs (liés aux phases tortonienne et villafranchienne) et extensifs (extension post-tectonique oligo-miocène comme dans l’ensemble du Maghreb, mais aussi existence d’une phase d’extension au Miocène terminal-Pléistocène inférieur synchrone du rifting du Bassin tyrrhénien). Cette alternance compression-extension induit plusieurs inversions de subsidence. L’étude tectonique effectuée aux abords de ces décrochements permet non seulement d’apporter des précisions sur l’évolution spatiale des déformations mais aussi d’établir les relations tectono-sédimentaires caractérisant chaque époque du Mio-Plio-Quatemaire : bassins subsidents sur les décrochements, installation de bassins lacustres sur barrages morphostructuraux, variations d’épaisseur et de faciès liées aux failles synsédimentaires

Single-crystal-to-single-crystal transformation and catalytic properties of new hybrid perhalidometallates

Two new organic–inorganic salts of perhalidometallates with protonated organic amine cations have been synthesized and characterized by X-ray diffraction and thermal analysis. (CHBMAH2) ZnBr4·3/2H2O 1 and (CHBMAH2 )ZnCl4 4 [(CHBMAH2 )2+: 1, 3-cyclohexanebis(methylammonium)] were obtained in single-crystal form. The crystal packing in all of the obtained compounds is governed by the formation of various non-covalent intermolecular forces between tetrahalidometallate anions and organic cations, assisted by water molecules in the hydrates. Hirshfeld surface analysis denotes that the most important contributions to the crystal packing are X···H/H···X (X: Cl, Br, I) and H···H interactions. Interestingly, the compound 1, 3-cyclohexanebis(methylammonium)tetrachlorido-zincate (II) dihydrate, (CHBMAH2 )ZnCl4·2H2O 2, undergoes thermally-triggered single-crystal-to-single-crystal (SCSC) transformation upon dehydration to produce a supramolecular solid compound, 1, 3-cyclohexanebis(methylammonium) tetrachloridozincate (II), (CHBMAH2 )ZnCl4 4. The SCSC transformation causes changes in the lattice parameters and a structural rearrangement. Furthermore, the catalytic properties of (CHBMAH2 )ZnCl4·2H2O 2 and (CHBMAH2 )CdI4·2H2O 3 have been explored in the acetalization process using various uncommon alcohols, beyond methanol or ethanol, for the first time in the literature, with outstanding results, and opening the door to the formation of alternative acetals. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Authentication and authorisation in entrusted unions

This paper reports on the status of a project whose aim is to implement and demonstrate in a real-life environment an integrated eAuthentication and eAuthorisation framework to enable trusted collaborations and delivery of services across different organisational/governmental jurisdictions. This aim will be achieved by designing a framework with assurance of claims, trust indicators, policy enforcement mechanisms and processing under encryption to address the security and confidentiality requirements of large distributed infrastructures. The framework supports collaborative secure distributed storage, secure data processing and management in both the cloud and offline scenarios and is intended to be deployed and tested in two pilot studies in two different domains, viz, Bio-security incident management and Ambient Assisted Living (eHealth). Interim results in terms of security requirements, privacy preserving authentication, and authorisation are reported