4,437 research outputs found
Corrigendum to “Tribochemistry of graphene on iron and its possible role in lubrication of steel” [Carbon 106 (2016) 118–124](S0008622316303797)(10.1016/j.carbon.2016.05.025)
No full textThe authors wish to update the reference to a “forthcoming article” in the sentence at page 122: “The difference between the maximum and minimum heights of the [Formula presented] peaks is proportional to the potential corrugation, ΔWsep. As we describe in a forthcoming article, these two properties have general validity, i.e. they hold true in different materials” with the reference to the now published paper: M. Wolloch, G. Levita, P. Restuccia, M. C. Righi, Interfacial charge density and its connection to adhesion and frictional forces, Phys. Rev. Lett. 121 (2018) 026804
Feticismo e sentimenti
No full textIn questo volume appare, per la prima volta in lingua italiana, la traduzione del secondo capitolo del III tomo del monumentale Sistema di politica positiva, che segna l’ultima fase dell’opera del sociologo e filosofo francese Auguste Comte (1798-1857). Ne è oggetto il feticismo, già specificamente tematizzato in una lezione, la 52°, del Corso di filosofia positiva. Rispetto a quest’ultima emergono novità sostanziali, tali da autorizzare a parlare, più in generale, di un nuovo e «ultimo» Comte: insospettabile precursore dello strutturalismo, come argomenta tra l’altro nel suo contributo, in particolare attraverso Claude Lévi-Strauss, Lorenzo Scillitani; «padre fondatore» della sociologia tra i più sensibili al tema delle emozioni, come argomenta nella sua introduzione Paolo Iagulli, per il quale l’inedito primato del sentimento che caratterizza la nuova tematizzazione del feticismo è «solo» la spia della prospettiva sociologica generale del Comte più maturo. Impreziosiscono il volume le acute riflessioni di Roberto Righi, consegnate al contributo di chiusura
Motivi letterari nei libri per l’infanzia di Paolo Di Paolo
No full textThe article, organised in the form of a discussion, aims to analyse the themes and motifs of Paolo Di Paolo’s works that are addressed to young audiences. The author has recently published a large number of volumes directed just at younger readers. When beholding the titles that constitute the author’s bibliography, the reader is struck by Di Paolo’s predisposition to transform literary classics: as much in Giacomo il signor bambino as in the edition of the Divina Commedia, the author’s goal is to try to reach his new readers. Therefore, Di Paolo proves to be a prolific author of the genre; in fact, in his bibliography, volumes of fairy tales with a classic slant, such as La mucca volante, are listed as well.L’articolo contiene un’analisi di temi e di motivi delle opere di Paolo Di Paolo dirette al pubblico più piccolo. L’autore negli ultimi anni ha pubblicato un cospicuo numero di volumi indirizzati, infatti, proprio ai lettori più giovani. Ciò che stupisce scorgendo i titoli che costituiscono la bibliografia dell’autore, è la predisposizione a trasformare i classici della letteratura: tanto in Giacomo il signor bambino quanto nell’edizione della Divina Commedia l’obiettivo è cercare di raggiungere i lettori più giovani. Di Paolo si dimostra, quindi, un autore prolifico del genere, tant’è che nell’elenco non mancano volumi fiabeschi dal taglio classico come La mucca volante. Analizzare le opere giovanili dello scrittore costituisce un fatto inedito
Tribochemistry of graphene on iron and its possible role in lubrication of steel
No full textRecent tribological experiments revealed that graphene is able to lubricate macroscale steel-on-steel sliding contacts very effectively both in dry and humid conditions. This effect has been attributed to a mechanical action of graphene related to its load-carrying capacity. Here we provide further insight into the functionality of graphene as lubricant by analysing its tribochemical action. By means of first principles calculations we show that graphene binds strongly to native iron surfaces highly reducing their surface energy. Thanks to a passivating effect, the metal surfaces coated by graphene become almost inert and present very low adhesion and shear strength when mated in a sliding contact. We generalize the result by establishing a connection between the tribological and the electronic properties of interfaces, which is relevant to understand the fundamental nature of frictional forces
Bring a friend! Privately or publicly?
No full textWe study the optimal referral strategy of a seller and its relationship with the type of communication channels among consumers. The seller faces a partially uninformed population of consumers, interconnected through a directed social network. In the network, the seller oers rewards to informed consumers (in uencers) conditional on inducing purchases by uninformed consumers (influenced). Rewards are needed to bear a communication cost and to induce word-of-mouth (WOM) either privately (cost-percontact) or publicly (xed cost to inform all friends). From the seller's viewpoint, eliciting Private WOM is more costly than eliciting Public WOM. We investigate (i) the incentives for the seller to move to a denser network, inducing either Private or Public WOM and (ii) the optimal mix between the two types of communication. A denser network is found to be always better, not only for information diusion but also for seller's prots, as long as Private WOM is concerned. Dierently, under Public WOM, the seller may prefer an environment with less competition between informed consumers and the presence of highly connected in uencers (hubs) is the main driver to make network density benecial to prots. When the seller is able to discriminate between Private and Public WOM, the optimal strategy is to cheaply incentivize the more connected people to pass on the information publicly and then oer a high bonus for Private WOM
Pier Paolo Pasolini e la società: il "sogno di una cosa" travolto dalla "nuova preistoria"
No full textL’articolo prende in esame – nel centenario della nascita – il “pensiero politico” di Pier Paolo Pasolini. Vengono pertanto scandagliati (soprattutto) i suoi scritti sulla società, ma frequenti sono le incursioni nella letteratura e soprattutto nel cinema di questo autore del tutto originale. Ne emerge lo spessore di concetti spesso usati dal poeta per analizzare e criticare il presente: Nuova Preistoria, nuovo capitalismo, consumismo, edonismo, il Potere, il Palazzo, il Processo, sviluppo e progresso, sacralità in primis. Si evidenzia inoltre come l’occhio e il giudizio di Pasolini siano stati principalmente guidati dalla passione e solo di rimando dalla ragione. Un ruolo non secondario nella sua percezione del reale ha inoltre assunto la sua omosessualità. Nella parte finale dello scritto si analizzano alcuni strumenti tecnici utilizzati dall’autore per svolgere la propria opera di comprensione del presente e della sua conseguente traduzione artistico-critica.The article examines - in the centenary of his birth - the "political thought" of Pier Paolo Pasolini.
Therefore, it scrutinizes (above all) his writings on society, but there are frequent incursions into the literature and especially into the cinema of this completely original author. What emerges is the depth of concepts often used by the poet to analyze and criticize the present: New Prehistory, new capitalism, consumerism, hedonism, Power, the Palace, the Process, development and progress, sacredness in primis. It also shows how Pasolini's eye and judgment were mainly guided by passion and only by reason. His homosexuality also played a significant role in his perception of reality. In the final part of the paper we analyze some technical tools used by the author to carry out his work of understanding the present and its consequent artistic-critical translation
Xsorb: a software for identifying the most stable adsorption configuration and energy of a molecule on a crystal surface
No full textMolecular adsorption is the first important step of many surface-mediated
chemical processes, from catalysis to tribology. This phenomenon is controlled
by physical/chemical interactions, which can be accurately described by first
principles calculations. In recent years, several computational tools have been
developed to study molecular adsorption based on high throughput/automatized
approaches. However, these tools can sometimes be over-sophisticated for
non-expert users. In this work, we present Xsorb, a Python-based code that
automatically generates adsorption configurations, guides the user in the
identification the most relevant ones, which are then fully optimized. The code
relies on well-established Python libraries, and on an open source package for
density functional theory calculations. We show the program capabilities
through an example consisting of a hydrocarbon molecule, 1-hexene, adsorbed
over the (110) surface of iron. The presented computational tool will help
users, even non-expert, to easily identify the most stable adsorption
configuration of complex molecules on substrates and obtain accurate adsorption
geometries and energies
Consecutive and domino processes for the synthesis of a heavily functionalised tricyclic system
No full textOne pot multi-bond forming reactions are one of the ways to address the ever growing demand for efficiency in organic synthesis that concern the chemical community. This paper presents a new three-component domino process that efficiently combines four bond-forming reaction steps into a single synthetic operation. From easily available linear starting materials and under very mild conditions, this process builds five new bonds and four new chiral centers, giving rise to the selective formation of a new class of fused heteroatomic tricyclic system, which may be exploited for the synthesis of biologically interesting aminopolyhydroxylared compounds. (C) 1998 Elsevier Science Ltd. All rights reserved
Zinc dialkyldithiophosphates adsorption and dissociation on ferrous substrates: An ab initio study
No full textZinc dialkyldithiophosphates (ZDDPs) have been commonly used as anti-wear additives in the automotive industry for the past 80 years. Despite their widespread use, a general agreement on their primary functioning mechanism is still lacking. The morphology and composition of the ZDDPs phosphate-based tribofilm, which is essential for its lubricant functioning, have been widely studied experimentally. However, the formation process and the relevant driving forces are still largely debated. In particular, it is unclear whether the stress-induced molecular dissociation occurs in the bulk oil or on the substrate. In this work, we employ ab initio density-functional theory simulations to compare ZDDP fragmentation in vacuum and over a reactive substrate, considering the effects of surface oxidation on the dissociation path. To do so, we developed a computational protocol to study the effects of shear stress on molecules. Our results show that the molecular dissociation is endothermic in the absence of a supporting substrate, while in the presence of an iron substrate, it becomes highly energetically favoured. Moreover, the presence of the substrate changes the reaction path, inducing the detachment of organophosphorus units from Zn-S ones. At the same time, surface oxidation reduces the molecule–substrate interaction. These findings provide valuable insights into the early stages of the formation of phosphate-based tribofilms
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