Alexandros di Giovanni Pascoli

Il mese di Febbraio sarà per me “grammaticaio”; ma spero a ogni modo di mandarvi il secondo poemetto. Però voglio sapere per qual giorno è assolutamente necessario che io lo mandi. Sarà più breve di Gog e Magog, e, spero, meno peggio. Così Pascoli, in una lettera del 31 gennaio 18951, annunciava ad Adolfo De Bosis come cosa già in cantiere il poema – Alexandros per l’appunto – destinato al secondo numero del «Convito», datato febbraio 1895 ma uscito in realtà nel marzo. Nella risposta (10 febbraio)2 De Bosis fissava la scadenza («la poesia vostra ben venga quanto prima sarà possibile. Il termine ultimo è il 28 corrente, poiché il secondo libro non potrà escire se non in marzo») e in più assumeva entusiasticamente l’impegno a pubblicare, a breve, terminato il ciclo dei dodici numeri della rivista, i ‘conviviali’ pascoliani:E quando avrò finito di stampare questi dodici libri del nostro Convito, ecco che cosa farò (ci avevo già pensato prima di ricevere l’ultima vostra e se ne era parlato con Antonio3). Farò l’edizione de’ vostri poemi: edizione del Convito, splendida, con illustrazioni di Sartorio, Michetti, e altri amici. E così fonderò la mia Casa Editrice, gloriosamente. Il progetto, si sa, non andò in porto. La raccolta dei Poemi conviviali uscì solo nel 1904, con altre proporzioni e con un impianto ideologico ormai lontano dal programma del «Convito»

Fluid-Assisted Strain Localization in Quartz at the Brittle/Ductile Transition

A mylonitic quartzite with conjugate and synthetic shear bands was investigated by Electron Backscatter Diffraction and optical microscopy to obtain insights on recrystallization mechanisms and strain localization in quartz at plastic to semibrittle conditions close to the brittle-ductile transition. The mylonitic quartzite deformed during late Miocene thrusting coeval with contact metamorphism in the high-strain domains of the Calamita Schists (Elba Island, Italy). Mylonitic deformation occurred from amphibolite to lower greenschist facies conditions during cooling of the aureole. Dynamic recrystallization, dominated by the activity of dislocation creep by prism slip, produced recrystallized quartz layers mantling relic large quartz porphyroclasts. Under decreasing temperature and fluid-rich conditions, quartz porphyroclasts acted as relatively rigid bodies and fractured along synthetic and conjugate C′ shear bands. Shear bands developed along kinematically favored orientations, just locally assisted by weak crystallographic planes in quartz. Fracturing along shear bands was assisted by cataclasis and fluid infiltration enhancing fracture propagation and healing by recrystallization and authigenesis of new quartz and phyllosilicate grains. The process enhanced the propagation of and strain localization in shear bands, with the development of bands of weak phyllosilicates. Furthermore, we observed the development of a c axis preferred orientation (CPO) related to dissolution and precipitation of new grains with their c axis oriented parallel to shear bands. This study highlights the importance of the interplay between brittle and crystal-plastic processes and fluid ingress in the semibrittle regime to understand deformation partitioning and strain localization

Flexible Physical Unclonable Functions based on non-deterministically distributed Dye-Doped Fibers and Droplets

The development of new anti-counterfeiting solutions is a constant challenge and involves several research fields. Much interest is devoted to systems that are impossible to clone, based on the Physical Unclonable Function (PUF) paradigm. In this work, new strategies based on electrospinning and electrospraying of dye-doped polymeric materials are presented for the manufacturing of flexible free-standing films that embed different PUF keys. Films can be used to fabricate anticounterfeiting labels having three encryption levels: i) a map of fluorescent polymer droplets, with non deterministic positions on a dense yarn of polymer nanofibers; ii) a characteristic fluorescence spectrum for each label; iii) a challenge-response pairs (CRPs) identification protocol based on the strong nature of the physical unclonable function. The intrinsic uniqueness introduced by the deposition techniques encodes enough complexity into the optical anti-counterfeiting tag to generate thousands of cryptographic keys. The simple and cheap fabrication process as well as the multilevel authentication makes such colored polymeric unclonable tags a practical solution in the secure protection of merchandise in our daily life