1,721,106 research outputs found
L’esperienza del Piano Lauree Scientifiche - Fisica presso l’Università di Trieste
Full text linkIl Piano Lauree Scientifiche (PLS) si prefigge di dare agli studenti delle scuole secondarie di secondo grado una corretta percezione della Fisica e del suo approccio ai fenomeni naturali, attraverso occasioni di incontri con i ricercatori e di esperienze dirette. Per questo l’attività svolta è soprattutto di tipo “hands-on” in laboratorio didattico, sia tradizionale che informatico, ma include anche esperienze dimostrative, conferenze, visite ai grandi laboratori, nonché opportunità di autovalutazione e consolidamento delle competenze per gli studenti che intendono iscriversi a corsi di laurea scientifici. L’attività sistematica introdotta con il PLS ha permesso di gettare le basi per una solida collaborazione Scuola-Università, per accompagnare i giovani nei primissimi passi verso l’entusiasmante avventura della ricerca scientifica
Interaction of carbon monoxide with Cu nanoclusters grown on alumina surface
Full text linkThe present work addresses the interaction of carbon monoxide with copper nanoclusters supported on an ultrathin alumina film grown on the Ni3Al(111) termination, acting as a template for a highly ordered nucleation. Through accu- rate quantum-mechanical calculations combined with experimental data, it has been found that the dissociation of carbon monoxide occurs at the copper nanoclusters, at variance with extended surfaces. The detailed mechanism is explained at the atomic level, unveiling the effects of cluster finite size, reconstruction, support, and carbon monoxide coverage. The small size of the nanoclusters allows to achieve an excep- tionally high local concentration of molecules at the cluster surface, considerably higher than the saturation limit for the single crystal surfaces. The high coverage facilitates the dissociation of the molecules, accompanied by carbon incorporation into the particles. We discuss the possibility of using other transition metals for an optimal seeding of the supported nanoparticles. In agreement with empirical findings, Pd is confirmed to be the best choice for a highly ordered nucleation
Una calcolatrice binaria senza saper contare
Full text linkWe report and comment on a recent experience of laboratory teaching carried out with a group of pupils of a primary school within the STEM2020 project, whose purpose was to give a very simple introduction to the binary system and to the functioning of computers to carry out the basic mathematical operations. Using the concept of “full / empty” and a few “rules of the game”, the pupils were guided to create a spreadsheet, or more generally, a mechanical calculator. The use of this mechanical calculator was shown to be suitable for everyone, even the youngest pupils of primary school, who lack basic math and calculus skills. The other students instead could verify its good functioning using the correspondence table between the binary coding of numbers and their standard representation in the decimal system.
Nel contributo viene illustrata una recente esperienza di didattica laboratoriale intrapresa con un gruppo di alunni di una Scuola primaria di primo grado nell’ambito del progetto STEM2020. La finalità perseguita consisteva nell’introdurre in modo molto semplice i partecipanti alla conoscenza del sistema binario e al funzionamento dei computer per svolgere le operazioni matematiche. Utilizzando il concetto di “pieno/vuoto” e poche “regole del gioco” si sono accompagnati gli alunni a realizzare un foglio di calcolo, o più generalmente una calcolatrice meccanica. La proposta si è dimostrata adeguata per tutti i partecipanti, perfino per quelli più piccoli appena entrati nella Scuola primaria e ancora completamente digiuni di addizioni, mentre quelli appena più grandicelli ne hanno potuto verificare il buon funzionamento con la tabella di corrispondenza tra codifica binaria dei numeri e rappresentazione standard nel sistema decimale
ZnSe/GaAs(001) heterostructures with defected interfaces: structural, thermodynamic and electronic properties
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First-Principle Study of Hydroxyl Functional Groups on Pristine, Defected Graphene, and Graphene Epoxide
No full textOxygen-containing functional groups can be present in considerable amount intentionally or unintentionally on graphene, and a complete reduction of graphene oxide is difficult to achieve. To address the origin of this behavior, we have performed pseudopotential density functional theory calculations to investigate in particular the adsorption of hydroxyl (OH) on perfect and defected graphene, individually and in the presence of other coadsorbed functional groups. We found that hydroxyl groups weakly adsorb on perfect graphene, easily aggregate, also with coadsorbed epoxy groups, and can react with each other with a barrier of about 0.5 eV forming water. Defect sites are more reactive for OH adsorption but play different roles. At variance with single vacancy defects where the OH adsorption is highly dissociative, Stone−Wales defects could stabilize the hydroxyl groups on the graphene basal plane, with a much stronger binding and higher barriers for recombination and water formation than pristine
Composition and strain dependence of band offsets at metamorphic In(x)Ga(1-x)As/In(y)Al(1-y)As heterostructures
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