Hydrogen bonding as a clustering agent in protic ionic liquids: like-charge vs opposite-charge dimer formation

The local structure of a series of homologous protic ionic liquids (PILs) is investigated using ab initio computations and ab initio-based molecular dynamics. The purpose of this work is to show that in PILs the network of hydrogen bonds may promote like-charge clustering between anionic species. We correlate the theoretical evidence of this possibility with viscosity experimental data. The homologous series of liquids is obtained by coupling choline with amino acid anions and varying the side chain. We find that the frictional properties of the liquids are clearly connected to the ability of the side chain to establish additional hydrogen bonds (other than the trivial cation–anion interaction). We also show that the large variation of bulk properties along the series of compounds can be explained by assuming that one of the sources of friction in the bulk liquid is the like-charge interaction between anions

Cholinium amino acid-based ionic liquids

Boosted by the simplicity of their synthesis and low toxicity, cholinium and amino acid-based ionic liquids have attracted the attention of researchers in many different fields ranging from computational chemistry to electrochemistry and medicine. Among the uncountable IL variations, these substances occupy a space on their own due to their exceptional biocompatibility that stems from being entirely made by metabolic molecular components. These substances have undergone a rather intensive research activity because of the possibility of using them as greener replacements for traditional ionic liquids. We present here a short review in the attempt to provide a compendium of the state-of-the-art scientific research about this special class of ionic liquids based on the combination of amino acid anions and cholinium cations

HAI VOGLIA DI STUDIARE… ANALISI DI UN’ESPRESSIONE IDIOMATICA: TRA PRAGMATICA E MORFOSINTASSI

Tradizionalmente, le unità linguistiche costituite da più parole, o “espressioni multi-parola”, sono considerate un fenomeno di interfaccia tra morfologia e sintassi che possono avere significato lessicale o grammaticale e che, non di rado, assumono funzioni pragmatico-discorsive. Lo studio analizza la locuzione verbale V+N avere voglia in due usi idiomatici correlati: la costruzione infinitiva, in cui avere voglia è seguito da una preposizione e da un verbo all’infinito, con un valore che indica inutilità nel compiere un’azione reiterata, e.g., hai voglia di gridare (tanto nessuno ti sente); l’interiezione hai voglia, utilizzata con funzione di accordo tra due interlocutori. Nonostante i due utilizzi di hai voglia siano attestati sin dalla fine dell’800, l’espressione idiomatica presenta caratteristiche plausibilmente riconducibili ai processi di lessicalizzazione e grammaticalizzazione, per esempio, un grado di fissità maggiore rispetto al passato e, in contesti più informali, coalescenza dei costituenti (avoglia, aivoglia). Avanzando in direzione empirica, questo studio adotta una prospettiva sincronica e un metodo di indagine quanti-qualitativo. Da un punto di vista quantitativo, vengono analizzate le occorrenze di hai voglia all’interno del web corpus ItTenTen20 e del corpus di italiano parlato KIParla. Per il primo corpus, viene effettuata un’analisi morfosintattica delle oscillazioni nella forma superficiale della costruzione, e.g., avoglia, aivoglia, avoja; e della scelta dell’elemento a destra della locuzione verbale, e.g., hai voglia di/a/che/te. Nel corpus di italiano parlato, invece, il valore pragmatico della costruzione viene ricostruito adottando l’approccio dell’analisi conversazionale a due produzioni degli intervistati: una di parlato spontaneo, una semi-strutturata. I risultati delle due diverse tipologie di analisi consentono di ragionare sul rapporto tra il mutamento linguistico e le esigenze pragmatiche della comunità di parlanti.   Hai voglia di studiare... Analysis of an idiomatic expression: between pragmatics and morphosyntax Traditionally, linguistic units consisting of several words,  also called ‘multi-word expressions’, are considered a phenomenon at the interface  of morphology and syntax that can have lexical or grammatical meaning and not infrequently assume pragmatic-discursive functions. The study analyses the verbal  expression V+N avere voglia in two related idiomatic usages: the infinitive construction, in which avere voglia is followed by a preposition and an infinitive verb, with a value  that conveys uselessness in performing a repeated action, e.g., hai voglia di gridare (tanto nessuno ti sente); the interjection hai voglia, used in function of agreement between two interlocutors. Although the two  usages of hai voglia have been attested since the end of the 19th century, the idiomatic expression presents  features that can  be  plausibly  traced back to  the  lexicalization and grammaticalization processes, for example, a greater degree of  fixedness than in the past and, in more informal contexts, coalescence of constituents (avoglia, aivoglia). Advancing in an empirical direction, this study adopts a synchronic perspective and a quanti-qualitative method of investigation. From a quantitative perspective, the occurrences of hai voglia within the web corpus ItTenTen20 and the spoken Italian corpus KIParla are analysed. For the former corpus, a morphosyntactic analysis of the different surface forms of the construction is carried out, e.g., avoglia, aivoglia, avoja; as well as  the choice  regarding the element to the right of the verbal expression, e.g., hai voglia di/a/che/te. On the other hand,  for the corpus of spoken Italian, the pragmatic value of the construction is reconstructed by adopting the conversational analysis approach to two productions of the interviewees:  a spontaneous speech production and a semi-structured interaction. The results of the two different types of analysis enable us to reflect  on the relationship between linguistic change and the pragmatic needs of the speech community. &nbsp

Random Surface Texturing of mc-Silicon for Solar Cells with Picosecond Lasers; a Comparison between 1064 nm, 532 nm and 355 nm Laser Emission Wavelengths

Multicrystalline Silicon was textured with picosecond laser. Different laser wavelengths (λ = 1064, 532, 355 nm) where compared regarding laser-induced damage. We found that λ = 355 nm picosecond radiation resulted in shallower defect-reach region

Intrusion and extrusion of liquids in highly confining media: bridging fundamental research to applications

Wetting and drying of pores or cavities, made by walls that attract or repel the liquid, is a ubiquitous process in nature and has many technological applications including, for example, liquid separation, chromatography, energy damping, conversion, and storage. Understanding under which conditions intrusion/extrusion takes place and how to control/tune them by chemical or physical means are currently among the main questions in the field. Historically, the theory to model intrusion/extrusion was based on the mechanics of fluids. However, the discovery of the existence of metastable states, where systems are kinetically trapped in the intruded or extruded configuration, fostered the research based on modern statistical mechanics concepts and more accurate models of the liquid, vapor, and gas phases beyond the simplest sharp interface representation. In parallel, inspired by the growing number of technological applications of intrusion/extrusion, experimental research blossomed considering systems with complex chemistry and pore topology, possessing flexible frameworks, and presenting unusual properties, such as negative volumetric compressibility. In this article, we review recent theoretical and experimental progresses, presenting it in the context of unifying framework. We illustrate also emerging technological applications of intrusion/extrusion and discuss challenges ahead

Optimization of the wetting-drying characteristics of hydrophobic metal organic frameworks via crystallite size: The role of hydrogen bonding between intruded and bulk liquid

Hypothesis: The behavior of Heterogeneous Lyophobic Systems (HLSs) comprised of a lyophobic porous material and a corresponding non-wetting liquid is affected by a variety of different structural parameters of the porous material. Dependence on exogenic properties such as crystallite size is desirable for system tuning as they are much more facilely modified. We explore the dependence of intrusion pressure and intruded volume on crystallite size, testing the hypothesis that the connection between internal cavities and bulk water facilitates intrusion via hydrogen bonding, a phenomenon that is magnified in smaller crystallites with a larger surface/volume ratio. Experiments: Water intrusion/extrusion pressures and intrusion volume were experimentally measured for ZIF-8 samples of various crystallite sizes and compared to previously reported values. Alongside the practical research, molecular dynamics simulations and stochastic modeling were performed to illustrate the effect of crystallite size on the properties of the HLSs and uncover the important role of hydrogen bonding within this phenomenon. Findings: A reduction in crystallite size led to a significant decrease of intrusion and extrusion pressures below 100 nm. Simulations indicate that this behavior is due to a greater number of cages being in proximity to bulk water for smaller crystallites, allowing cross-cage hydrogen bonds to stabilize the intruded state and lower the threshold pressure of intrusion and extrusion. This is accompanied by a reduction in the overall intruded volume. Simulations demonstrate that this phenomenon is linked to ZIF-8 surface half-cages exposed to water being occupied by water due to non-trivial termination of the crystallites, even at atmospheric pressure

Mechanism of Water Intrusion into Flexible ZIF-8: Liquid Is Not Vapor

Zeolitic Imidazolate Frameworks (ZIF) find application in storage and dissipation of mechanical energy. Their distinctive properties linked to their (sub)nanometer size and hydrophobicity allow for water intrusion only under high hydrostatic pressure. Here we focus on the popular ZIF-8 material investigating the intrusion mechanism in its nanoscale cages, which is the key to its rational exploitation in target applications. In this work, we used a joint experimental/theoretical approach combining in operando synchrotron experiments during high- pressure intrusion experiments, molecular dynamics simulations, and stochastic models to reveal that water intrusion into ZIF-8 occurs by a cascade filling of connected cages rather than a condensation process as previously assumed. The reported results allowed us to establish structure/function relations in this prototypical microporous material, representing an important step to devise design rules to synthesize porous media

Random Surface Texturing of mc-Silicon for Solar Cells with Picosecond Lasers; a Comparison between 1064 nm, 532 nm and 355 nm Laser Emission Wavelengths

Multicrystalline Silicon was textured with picosecond laser. Different laser wavelengths (λ = 1064, 532, 355 nm) where compared regarding laser-induced damage. We found that λ = 355 nm picosecond radiation resulted in shallower defect-reach region

Isomerization patterns and proton transfer in ionic liquids constituents as probed by ab-initio computation

We have recently shown that some protic ionic liquids (PILs) are characterized by an unexpected complex dynamic of proton transfer (M. Campetella et al., Phys. Chem. Chem. Phys. 19, 11,869, (2017)). These liquids are based on a combination of cholinium cations and amino acid (AA) deprotonated anions. The side chain proton migration, can take place both within the same anion and between different anions. The intra-molecular proton transfer leads to a tautomerization of the AA anion that gives rise to the appearance of an anionic zwitterionic form. The inter-molecular proton transfer is chemically more interesting since it might, at least in principle, point to a way to achieve a dry, fast conduction in materials that are otherwise very viscous and typically poor conductors. We examine here, by means of ab-initio computations, the basic mechanism of proton transfer in a variety of AA anions to find promising candidates as new materials for electrochemistry applications. © 201