La violenza “giustificata”: per un’Orestea sudafricana

In Athol Fugard’s Orestes, the reception of the ancient does not flow in a conventional manner, but generates an experimental and anomalous pièce which escapes the imposition of the written text, the definite characterization of the characters, the archetypal heritage from which this pièce starts. Fugard blends both the aeschylean trilogy and the Euripides’s Orestes, to create a type of hypertext that frames the dramatic vicissitudes of a white South-African young terrorist. This article investigates the genesis and the structure of the work, putting lights on the thematic and symbolic recurrence of the concepts of violence, justice and myth. Fugard suggests to overcome absurdities and atrocities through dialectical and conscious processes, instead of extremisms or bloody revolutions.Nell’Orestes di Athol Fugard la ricezione dell’antico non fluisce in maniera convenzionale, ma genera una pièce sperimentale, anomala, che sfugge alle imposizioni del testo scritto, alla caratterizzazione definita dei personaggi, al retaggio archetipico da cui prende l’abbrivio.Fugard fonde insieme sia la trilogia eschilea che l’Oreste di Euripide, una sorta di ipertesto che incornicia le drammatiche vicissitudini di un giovane terrorista bianco e sudafricano.Questo articolo si propone di indagare la genesi e la struttura dell’opera alla luce di ricorrenze tematiche e simboliche quali i concetti di violenza, di giustizia, di mito. L’autore, per dimostrare l’assurdità e l’atrocità di determinate circostanze, ne suggerisce il superamento non in estremismi o in rivoluzioni sanguinarie, ma in processi dialettici e coscienti

Risignificare Antigone The Island di Athol Fugard

This study aims to investigate The Island (1973), a South African rewriting of the Sophocles’s Antigone. The drama was conceived by Athol Fugard, the most acclaimed contemporary South African playwright, assisted by John Kani and Winston Ntshona, two actors-activists, as well as the unique interpreters of the pièce. In Fugard’s play, the existential path of the young Theban heroine intersects itself with the circumstances of a story that really happened in full apartheid interregnum: the impromptu staging of Antigone by prisoners of Robben Island (including Nelson Mandela), the penitentiary island off Cape Town. The theatre became not only an instrument of escape but above all of resistance, better still of survival

Electro-Oxidation of p-Silicon in Fluoride-Containing Electrolyte: A Physical Model for the Regime of Negative Differential Resistance

When Si is anodically oxidized in a fluoride containing electrolyte, an oxide layer is grown. Simultaneously, the layer is etched by the fluoride containing electrolyte. The resulting stationary state exhibits a negative slope of the current-voltage characteristics in a certain range of applied voltage. We propose a physical model that reproduces this negative slope. In particular, our model assumes that the oxide layer consists of both partially and fully oxidized Si and that the etch rate depends on the effective degree of oxidation. Finally, we show that our simulations are in good agreement with measurements of the current-voltage characteristics, the oxide layer thickness, the dissolution valence, and the impedance spectra of the electrochemical system.Comment: 19 pages, 13 figures, accepted for publication in EPJ S

Direct evidence of oxygen evolution from Li1+ x (Ni1/3Mn1/3Co1/3)1− x O2 at high potentials

Li1+x (Ni1/3Mn1/3Co1/3)1−x O2 (NMC) oxides are among the most promising positive electrode materials for future lithium-ion batteries. A voltage "plateau” was observed on the first galvanostatic charging curve of NMC in the extended voltage region positive to 4.5V vs. Li/Li+ for compounds with x>0 (overlithiated compounds). Differences were observed in the cycling stability of the overlithiated and stoichiometric (x=0) NMC oxides in this potential region. A differential plot of the charge vs. potential profile in the first cycle revealed that, for the overlithiated compounds, a large irreversible oxidative peak arises positive to 4.5V vs. Li/Li+, while in the same potential region only a small peak due to the electrolyte oxidation is detected for the stoichiometric material. Differential Electrochemical Mass Spectrometry (DEMS) was used to investigate the high voltage region for both compounds and experimental evidence for oxygen evolution was provided for the overlithiated compounds at potentials positive to 4.5V vs. Li/Li+. No oxygen evolution was detected for the stoichiometric compoun

Il simulacro dell’illusione. Les Nègres di Jean Genet

Les Nègres (The Blacks, 1958) is perhaps the most discussed work of Jean Genet’s dramatic corpus. The exegetical perplexities that gravitate around this work focus on several aspects, including the reliability of its ritualistic status. The purpose of this study is, in fact, to establish if Les Nègres is a ritual or if, on the contrary, it represent its mystification. The analysis conducted is on two levels: at the beginning, it identifies the levels of falsification present in the drama. Secondly, it gives the play a ritual apparatus that does not, however, exhaust its complexity. Les Nègres, as this paper will try to demonstrate, is a performance in the Schechnerian sense, which is the sum and the interaction of apparently irreconcilable qualities: efficacy  and entertainment.  Les Nègres (I Negri, 1958) è forse l’opera più discussa del corpus drammatico di Jean Genet. Le perplessità esegetiche che le gravitano intorno si concentrano su più aspetti, su tutti l’affidabilità del suo status ritualistico. Scopo di questo studio è, per l’appunto, stabilire se il dramma di Genet sia un rituale o se, al contrario, ne rappresenti una sua mistificazione. L’analisi condotta si muove su due livelli: all’inizio, individuando i livelli di falsificazione presenti nel dramma. In secondo luogo, riconoscendo all’opera un apparato rituale che non esaurisce però la sua complessità. Les Nègres, come si proverà a dimostrare, è una performance nell’accezione schechneriana, ovvero la somma e l’interazione di qualità apparentemente inconciliabili: efficacia  e intrattenimento. 

Modeling of electrochemical oxide film growth -- a PDM refinement

The Point Defect Model (PDM) is known for over 40 years and has brought deeper insight to the understanding of passivity. During the last decades it has seen several changes and refinements, and it has been widely used to analyze growth kinetics of different alloys. Nevertheless, the model has been based on still unconfirmed assumptions, as constant and potential independent electric field strength. To overcome this limitation, we introduce a Refined PDM (R-PDM) in which we replace those assumptions by using additional equations for charge distribution including new physically valid boundary conditions based on considering finite dimensions for the defects by introduction of two defect layer at the film boundaries and by calculating the potential drop at the surface of the film towards the solution over the compact double layer. The calculations by the R-PDM show that the original PDM assumptions are only valid for very specific parameter combinations of oxide film growth and vacancies transport and cannot generally be taken for granted. We believe our findings of electric field and potential drop dependency on the external potential to pave the way for a more realistic description of passive layer formation

Thermodynamic analysis and energy efficiency of thermal desalination processes

This thermodynamic study examines the principles governing energy efficiency and specific energy requirement intrinsic to thermal desalination processes. The practical performances of desalination technologies are investigated and related to the fundamental physical limitations of the processes. The energy efficiency of any thermal desalination process fulfils a limitation similar to the well-known Carnot law for heat engines. The efficiency of a single-effect distiller is limited by a function of the boiling point elevation of the solution. Further analysis shows that, although this can appear as paradoxical, a higher energy efficiency is obtained by a solution with higher boiling point elevation. For multiple-effect distillation, the limit also depends on the temperature drops across the heat exchangers. Comparison with empirical data indicates that these limits are actually approached in real plants. Our study discusses the thermodynamic framework for understanding the performances of thermally-driven desalination technologies, emphasizing the role of the boiling point elevation. The results can be also seen as rules-of-thumb for designing and evaluating the performances of a multiple-effect distillation unit, based only on the properties of the solution to be distilled, in particular, the boiling point elevation

Thermally Regenerable Redox Flow Battery for Exploiting Low-Temperature Heat Sources

Harvesting energy from low-temperature heat sources (<100°C) would enable the exploitation of currently untapped renewable sources. Recently proposed techniques fail to reach suitable efficiencies. We propose here a redox flow battery that can be recharged by a thermal process, distillation. The electrochemical cell produces electrical energy from the mixing free energy of two sodium iodide aqueous solutions at different concentrations. The electrochemical cell is based on the technology of sodium ion-conducting ceramics and is coupled with a liquid-liquid extraction process, performed by an unconventional device, the "through-liquid-exchanger." Our technique bypasses the bottleneck of other similar techniques by working with solutions at very high concentrations. Our initial experiments prove an unprecedented energy efficiency (ratio between the electrical work produced and the incoming heat necessary to restore the initial solutions concentrations) of 3% from a heat source <100°C and a power density of 10 W/m2, with the possibility of further improvements. © 2020 The Author(s) The flow battery described by Facchinetti et al. can be recharged by distillation with heat sources <100°C. It enables the efficient exploitation of currently untapped clean and renewable heat sources (e.g., low-concentration solar heat collectors). The design is based on a solid-state ion conductor and includes an unconventional device based on liquid-liquid exchange

On the Analysis of Non-stationary Impedance Spectra

In this work we study the possibility to analyze the non-stationary impedance spectra by employing standard equivalent circuits. For this purpose, the dynamic multi-frequency analysis (DMFA) is introduced and compared with a set of consecutive stationary impedance spectra. In order to prove the hypothesis, the data are obtained by the simulation in the time domain of the electron transfer process between an electrode and a free-diffusing redox couple in solution. During the simulation, the system is perturbed with a cyclic voltammetry super-imposed to a small multisine perturbation (DMFA) or with a series of stationary impedance spectroscopies. Also, a new fitting algorithm, which takes into account the correlation between consecutive spectra, is proposed and tested. Although the Randles circuit can be used to fit both dynamic and stationary impedance spectra, the values of the fitting parameters are different and depend on the direction of the scan and on the rate. This is related to the influence of the diffusion profile on the fitting parameters