High entropy alloys (HEA) represent a kind of materials with unique structural and functional properties, and have attracted wide attentions in many fields including hydrogen storage. Due to the huge ...diversity in the composition of HEAs, novel hydrogen storage materials with superior comprehensive performance are expected to be developed following the concept, with some notable progress made in the past decade. In this study, the present research status in HEAs for hydrogen storage is summarized from the aspects of theoretical guide, composition and preparation, microstructure and hydrogen storage properties. Moreover, the key issues in future development and possible application scenarios are analyzed.
•A rigorous literature survey on the status and trend of high entropy alloys for hydrogen storage was presented.•Pros and cons of hydrogen storage HEAs were shown regarding capacity, thermal stability, kinetics, activation and cycling.•The promising scenarios for hydrogen storage HEAs were summarized and problems to solve pointed out.
The paper offers a reading of Jason’s use of sparsity, seriousness, and reduction as a concealment of a technique that is based on multifaceted ambiguity involving the blending of genres, a playfully ...intertextual attitude, and surprising emotional depth of character and story. It discusses the connection between humour and visual, textual, and structural ambiguity in Jason’s works, as well as ambivalence in the reader’s response, illustrates Jason’s combination of incongruous genres and simultaneous employment of motifs from children’s literature and various genre movies (such as science fiction, crime thrillers, heist movies, and horrors), and explores Jason’s technique of subverting expectations of comic relief by withholding certain structural parts of a joke (typically a punchline) or inserting an unexpected element (such as psychological depth).
The paper employs Michel Foucault’s ideas on heterotopias, outlined in his essay Of Other Spaces (1984), to analyse the interaction of humour and spaces in Edward Gorey’s works, with special emphasis ...on the book The Evil Garden (1966). Foucault’s theory of heterotopias is used to provide an understanding of Gorey’s fusion of sombre places and macabre tales with his characteristically dry humour and to examine what Gorey’s heterotopias can tell us about the problem of the categorisation of Gorey as an author of children’s literature. In the reading of The Evil Garden, the paper illustrates how Gorey’s disturbing heterotopias achieve a hybridity of spaces, genres, tones, and reader roles in order to encourage polyvalent readings. Gorey plays with the juxtaposition of various heterotopias, destabilising the reader’s position through recurring motifs and intertextual allusions, but the one element that is represented in all those “other” places is invariably humour in all its different forms. It is precisely at the intersection of the various spaces which collide in heterotopias that Gorey’s dark humour emerges and performs its subversive function.
The hydrogen sorption kinetics of MgH2‒VO2(B) composites synthesised by mechanical milling have been studied. The microstructural properties of composites were characterized by means of X-ray ...diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), Particle size analysis (PSD), while sorption behaviour was followed by differential scanning calorimetry (DSC) and Sievert measurements. Results have shown that although desorption temperature reduction is moderate; there is a substantial improvement in hydrogen sorption kinetics. The complete desorption of pure MgH2 at elevated temperature takes place in more than 30 min while the composite fully desorbs in less than 2 min even at lower temperatures. It has been shown that the metastable γ–MgH2 phase and the point defects have a decisive role in desorption process only in the first sorption cycle, while the second and the subsequent sorption cycles are affected by microstructural and morphological characteristics of the composite.
•Effect of synthesized VO2 (B) polymorph on H desorption from MgH2 is studied.•Desorption temperature is reduced by 55 °C.•Cyclability of material is very fast and desorption of 4.3wt.% occurs in 75 s.•Apparent activation energy obtained by JMA is reduced to ∼60 kJ mol−1.•Improved kinetics is achieved by formation of VO2/VH2 system.
The impact of boron doping on MgH2 bonding mechanism, hydrogen diffusion and desorption was calculated using density functional theory (DFT). Atomic interactions in doped and non-doped system and its ...influence on hydrogen and vacancy diffusion were studied in bulk hydride. Slab calculations were performed to study hydrogen desorption energies from (110) boron doped surface and its dependence on the surface configuration and depth position. To study kinetics of hydrogen diffusion in boron vicinity and hydrogen molecule desorption activation energies from boron doped and non-doped (110) MgH2 surface Nudged Elastic Band (NEB) method was used. Results showed that boron forms stronger, covalent bonds with hydrogen causing the destabilization in its first and second coordination. This leads to lower hydrogen desorption energies and improved hydrogen diffusion, while the impact on the energy barriers for H2 desorption from hydride (110) surface is less pronounced.
•Boron doping of MgH2 causes weakening of H–H interactions.•Introduction of B leads to MgH2 crystal lattice destabilization.•Hydrogen diffusion is improved in boron vicinity in Mg15BH32 comparing to MgH2.•MgH2 doping with B lowers the hydrogen desorption energy from saturated surface.
The article analyses the humour in Hermann Huppen and Morphée’s series of comic books about a boy called Nick, with primary focus on the third issue, Ça, c’est Filarmo, Nic That’s Filarmo, Nick. ...Drawing on Bakhtin’s theory of the carnivalesque, the article identifies a variety of humorous devices, including wordplay, puns, quotations, unusual transformations, and mésalliances. Special attention is paid to the visual level of the comic book. Humour is located in visual metamorphoses, invisible “phantom” panels, and the incongruity between words and images. The article also addresses the comic book’s intertextual ties with Little Nemo in Slumberland, a series of comic strips from the early 20th century, and compares the way authority is represented and challenged in the two texts. The impossible spaces that Nick traverses within the chronotope of the road are examined as places that invert the usual hierarchies and relations, allowing Nick to experience a level of agency usually reserved for adults. The end of Nick’s travels across the dreamscape is examined as both a departure and continuation of the pattern from Little Nemo, and as a logical conclusion of a temporary carnivalesque subversion of traditional structures that dominate the adult world.
Hydrogen desorption properties of MgH2 ball milled with two different TiO2 polymorphs, rutile and anatase, were studied. Structural characterization has been done by X-ray diffraction (XRD) analysis, ...particle size analysis (PSD) and scanning electron microscopy (SEM). The mechanism of desorption and the apparent activation energy for desorption were investigated by applying isoconversional kinetic analysis of DTA spectra, while desorbed species were followed by TPD coupled with mass spectroscopy. It has been demonstrate that the addition of rutile TiO2 significantly decrease the apparent activation energy for desorption (Edesa), while addition of anatase titania has negligible influence on Edesa. Such behaviour could be explained in terms of the same crystal structure of rutile TiO2 and MgH2. Further, the mechanism of desorption changes from Avrami–Erofeev n = 3 for pure MgH2 to Avrami–Erofeev n = 4 for composite materials.
•Effect of different TiO2 phases on H desorption from MgH2–TiO2 composite is studied.•Addition of rutile notably reduce the apparent activation energy for desorption.•Such behaviour is due to the same crystal structure of rutile TiO2 and MgH2.
A new optimisation method for equalising the group delay frequency response of the discrete transfer function of recursive digital filters, so-called tan filters, is presented in this paper. The ...method is based on an algorithm that is used for a stable all-pass filter approximation. Allpass filter acts as a group delay equaliser, with the purpose of equalising group delay of the discrete tan filter in a maximal flat sense. The algorithm relies on a set of simultaneous nonlinear equations. These set equations are derived directly from the flatness conditions of the equalised group delay response at the origin in the analogue
-domain, in order to obtain the unknown coefficient values of the discrete allpass filter. The iterative method most widely used for solving set nonlinear equations and Symbolic Math Toolbox for Matlab features for finding numerical solutions are presented in detail.
In the given examples, firstly a discrete Butterworth tan filter was designed by using transfer function poles in closed form. Secondly, the Butterworth tan filter was augmented with cascade connection of non-minimum phase all-pass discrete filter, in order for the group delay response of the whole filter to be equalised in a maximally flat sense.
The ability of Bader's charge density topology analysis to explain various material properties has been examined for simple ionic systems of alkali halides and alkali hydrides. It was established ...that despite the fact that most of them share the same rock salt crystal structure phase, some of them belong to different topological classes. This fact was used to explain various experimentally observed properties of these materials, and to discuss their deviations from expected trends. Some phase transitions observed in these systems, and their possible relation to changes in the charge density topology have been also investigated from the same point of view. Reasons for anion-anion bond formation in some of them and its features are discussed, as well.
•Charge density topology of alkali halides and hydrides was investigated.•Investigated compounds belong to either of two different topological classes.•Topological transitions in principle possible for KBr and RbI.•Topological transitions hindered by structural phase transitions.•In non-local density picture NaH transitional form between two topological classes.
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