170,226 research outputs found
“Lantern-Shaped” Platinum(III) Complexes with Axially Bound 9-Ethylguanine or 1-Methylcytosine (L) of General Formula [Pt2{HN=C(But)O}4L2](NO3)2
No full textThe synthesis, NMR characterization, and X-ray crystallography of “lantern-shaped” platinum(III) complexes with four pivaloamidate bridging ligands and two 9-ethylguanines (9-EtG) or 1-methylcytosines (1-MeC) in axial positions are reported: cis-N2O2-[Pt2{HN=C(But)O}4(9-EtG)2](NO3)2 and cis-N2O2-[Pt2{HN=C(But)O}4(1-MeC)2](NO3)2. The last complex is, to the best of our knowledge, the first dinuclear compound of platinum(III) with axially bound 1-MeC
Synthesis and structural characterization of isomeric 'lantern-shaped' platinum(III) complexes of formula [Pt-2(PPh3)X{N(H)C(R)O}(4)](NO3)(2) (X = PPh3, H2O)
No full textThe platinum(III) lantern type complexes [Pt-2(PPh3)(2){N(H)C(R)O}(4)](NO3)(2) [R =Me (1), Bu-t (2)], and [Pt-2(H2O)(PPh3)- {N(H)C(Bu-t)O}(4)](NO3)(2) (3) were synthesized and characterized by H-1 NMR and X-ray crystallography (2 and 3). The compounds can give rise to formation of isomers differing for the sets of equatorial donor atoms around each platinum, (NO)-O-3/NO3 orN(2)O(2), and, in the case of N2O2, for the cis or trans geometry. The effect of the anion upon the chemical shifts of NH protons was studied for NO3-, BF4-, and ClO4-. The stability of phosphine axial ligands in the complexes (NO)-O-3/NO3-[Pt-2(PPh3)(2){N(H)C(R)O}(4)](NO3)(2) as a function of the set of donor atoms was also studied. The complex (NO)-O-3/NO3-3 is the fist non-symmetric lantern-type platinum dimer to be characterized by X-ray diffraction. Comparison of the platinum/axial ligand bond distances in different complexes of this type allows to conclude that two factors contribute to the lengthening of axial bonds: the strong trans labilizing effect of the intermetallic bond and the trans-influence of the axial ligand on the second platinum unit
L’IMPATTO DEL PNRR SUL TURISMO DEL POST PANDEMIA TRA VECCHI SCHEMI E NUOVE SFIDE
No full textIl turismo svolge un ruolo strategico per l’economia italiana. In Europa contribuisce per oltre il 10% del PIL (tra attività diretta- mente connesse e indotto) e per oltre il 12% dell’occupazione: l’Europa è infatti la prima destinazione turistica mondiale e nel 2019 rappresentava poco più del 50% del totale degli arrivi inter- nazionali (quasi 1,5 miliardi di persone a livello mondiale) (OCSE, 2020).
La pandemia da Covid-19 ha colpito molto duramente questo settore incidendo in modo travolgente e istantaneo sulle principali determinanti del movimento turistico a livello globale: il tempo libero, il reddito disponibile e soprattutto la libertà di movimento. Le restrizioni alla mobilità interna (lockdown) e internazionale a partire dalla primavera 2020 hanno determinato un improvviso e repentino crollo della domanda, impedendo la possibilità stessa di viaggiare e quindi di fare turismo. La crisi economica generata dal Covid-19, inoltre, riducendo la disponibilità di reddito per molte persone, ha aumentato l’incertezza sul futuro e influito negativa- mente sulla predisposizione a viaggiare. È noto che la disponibilità di moneta per il turismo sia correlata in modo diretto al livello di reddito e che la spesa turistica diminuisca più che proporzional- mente al diminuire del reddito, specie quando questo raggiunge livelli medio bassi, fino ad azzerarsi completamente sotto certi limiti di reddito. Nonostante l’avvio e la rapida diffusione della campagna vaccinale e il varo di nuove misure di contenimento per regolamen- tare e mettere in sicurezza il settore dei viaggi, anche nel 2021 il mercato turistico non si è ripreso; al contrario, esso ha visto ulteriormente aggravare la situazione a causa dell’impennata dei contagi registrata in autunno con la diffusione di nuove varianti del virus, che hanno prodotto un elevato numero di quarantene e isolamenti, cui sono seguite cancellazioni in massa di vacanze già prenotate e il caos nei trasporti dovuto al mancato decollo di centinaia di aerei. Così, ai motivi precedenti, si è aggiunta un’ulte- riore causa di crisi legata all’incertezza che stavolta non riguarda soltanto le aspettative di reddito, ma ha a che fare con il timore che le misure di sicurezza e protezione adottate nei diversi Paesi siano inefficaci, una sensazione destinata a rappresentare un elemento strutturale nelle scelte di viaggio del turista post-pandemico
Structural characterization of the 'lantern-shaped' platinum(III) complex [Pt2Cl2{N(H)C(Bu-t)O}(4)]
No full textThe synthesis of a new platinum(III) 'lantern-shaped' complex with amidate bridging ligands, [Pt2Cl2{N(H)C(Bu-t)O}(4)] (1), is described. Complex I has been structurally characterized by X-ray diffraction and compared with the related compound [Pt2I2{N(H)C(Me)O}(4)] (2). The two complexes exhibit very short N...O bite distances which are similar in the two cases but the Pt(III)-Pt(III) distance is significantly shorter in 1 than in 2. (C) 2002 Elsevier Science Ltd. All rights reserved
Empirical investigation of retail gasoline prices
No full textThis paper explores the nature of price variation in the retail gasoline sector with a novel approach. An empirical model is proposed that jointly analyses: i) the spatial interaction between stations in price setting; ii) the direct and the indirect effect of local competition on prices; iii) the role of territorial factors, generally neglected in the studies on gasoline prices. For all these purposes, variables at sub-municipal level are constructed. The results of the empirical model, tested on the city of Rome, confirm the spatial price interaction across stations. Moreover, evidence of direct and indirect effects of local competition on prices is found: the competitive forces acting in the gasoline sector are not bounded within a local market but they spill over across local markets. Micro-territorial variables turn out to have a sizeable influence on prices, particularly the real estate value. When these variables are added to the model, the strength of spatial interaction weakens. This suggests that including micro-territorial variables in the empirical specification strongly contributes to explain the variation of gasoline prices and to accurately detect the spatial dependence
Interpolation methods to predict the influence of inlet airflow states on desiccant wheel performance at low regeneration temperature
No full textEmpirical investigation of retail fuel pricing: The impact of spatial interaction, competition and territorial factors
No full textThis paper explores the determinants of fuel prices by proposing an empirical framework that integrates three kinds of influencing factors: spatial interaction, competition and territorial factors. For competition, we define a general variable, the presence of competing stations within a radius, and two specific variables, the presence of low-cost stations and the presence of same-brand stations. We proceed with a step-wise adjustment of the radius, by gradually increasing it, to evaluate the spatial scope of different competition effects. Using data on prices of fuel stations in Rome, Italy, we estimate spatial econometric models that provide evidence of spatial dependence in price between stations. We also find that competition affects prices, but the relevance of its impact depends on radius length. Finally, the territorial factors remarkably influence prices. If these factors are introduced in the model, the magnitude of spatial parameters weakens, allowing to accurately assess the intensity of spatial dependence
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