Search results for "Comet"

Morphology, Rheological and Mechanical Properties of Isotropic and Anisotropic PP/rPET/GnP Nanocomposite Samples

2021

The effect of graphene nanoplatelets (GnPs) on the morphology, rheological, and mechanical properties of isotropic and anisotropic polypropylene (PP)/recycled polyethylene terephthalate (rPET)-based nanocomposite are reported. All the samples were prepared by melt mixing. PP/rPET and PP/rPET/GnP isotropic sheets were prepared by compression molding, whereas the anisotropic fibers were spun using a drawing module of a capillary viscometer. The results obtained showed that the viscosity of the blend is reduced by the presence of GnP due to the lubricating effect of the graphene platelets. However, the Cox–Merz rule is not respected. Compared to the PP/rPET blend, the GnP led to a slight incre…

Adsorption of CO and N 2 molecules at the surface of solid water. A grand canonical Monte Carlo study

2020

International audience; The adsorption of carbon monoxide and nitrogen molecules at the surface of four forms of solid water is investigated by means of grand canonical Monte Carlo simulations. The trapping ability of crystalline Ih and low-density amorphous ices, along with clathrate hy-drates of structures I and II, are compared at temperatures relevant for astrophysics. It is shown that, when considering a gas phase that contains mixtures of carbon monoxide and nitrogen, the trapping of carbon monoxide is favored with respect to that of nitrogen at the surface of all solids, irrespective of the temperature. The results of the calculations also indicate that some amounts of molecules can …

Pressure dependence of the demixing of polymer solutions determined by viscometry

1981

From the break-down in the viscosity of a polymer solution, associated with the entrance into the two phase region, the pressure dependence of the demixing temperatures of solutions of polystyrene (M = 600.000) in cyclohexane, cyclopentane, diethylmalonate and 1-phenyldecane was measured up to 1000 bar. The application of pressure increases the solubility of polystyrene in cyclopentane and diethylmalonate, but decreases that in 1-phenyldecane; in the case of cyclohexane, a pressure of optimum miscibility is observed at ca. 120 bar.

Material valorisation of amorphous polylactide. Influence of thermo-mechanical degradation on the morphology, segmental dynamics, thermal and mechani…

2012

[EN] This paper reports the effects of multiple mechanical recycling on the structure and properties of amorphous polylactide (PLA). The influence of the thermo-mechanical degradation induced by means of five successive injection cycles was initially addressed in terms of macroscopic mechanical properties and surface modification. A deeper inspection on the structure and morphology of PLA was associated to the thermal properties and viscoelastic behaviour. Although FT-IR analysis did not show significant changes in functional groups, a remarkable reduction in molar mass was found by viscometry. PLA remained amorphous throughout the reprocessing cycles, but the occurrence of a cold-crystalli…

Michele Cometa, Il Trionfo della Morte. Un’allegoria della modernità

2018

La lettura del libro di Michele Cometa sull'affresco il Trionfo della Morte, esposto presso la Galleria Regionale di Palazzo Abatellis di Palermo, è affrontata attraverso l'individuazione di due sentieri di indaginedue sentieri solo apparentemente paralleli. Quali sono le due piste? Una è dedicata all’Ékphrasis, cioè alla descrizione delle immagini; l’altra alla fine, alla conclusione, alla morte. Questi due itinerari trovano nella dimensione del tempo, o se si vuole nella sua negazione, l’humus comune. L’affresco realizzato per l’Ospedale nuovo di Palazzo Sclafani occupa, dai primi anni Cinquanta del XX secolo, la parete di fondo della chiesa di Santa Maria della Pietà annessa a palazzo Ab…

Eterogeneità delle preferenze e rilevanza degli indicatori psicometrici nelle decisioni di scelta modale: le prospettive per il trasporto delle merci…

2011

Determining the Geometry of Hydrogen Bonds in Solids with Picometer Accuracy by Quantum-Chemical Calculations and NMR Spectroscopy

2005

The structure of multiply hydrogen-bonded systems is determined with picometer accuracy by a combined solid-state NMR and quantum-chemical approach. On the experimental side, advanced 1H-15N dipolar recoupling NMR techniques are capable of providing proton-nitrogen distances of up to about 250 pm with an accuracy level of +/-1 pm for short distances (i.e., around 100 pm) and +/-5 pm for longer ones (i.e., 180 to 250 pm). The experiments were performed under fast magic-angle spinning, which ensures sufficient dipolar decoupling and spectral resolution of the 1H resonance lines. On the quantum-chemical side, the structures of the hydrogen-bonded systems were computationally optimised, yieldin…

Influence of chain length on the molecular dynamics of an aliphatic ionene

1998

An aliphatic random copolymer ionene (a cationic polyelectrolyte with N + in the repeat unit), was fractionated with the continuous polymer fractionation and investigated for its molecular weight dependent properties. The fractions were analyzed with GPC and capillary viscometry for their molecular weight. Glass transition temperatures were determined with DSC and a strong molecular weight dependence was observed, but no influence in the ionic conductivity was observed. The temperature dependency of ionic conductivity in ionenes is described.

Satisfaction and frustration of autonomy and relatedness needs: Associations with parenting dimensions and psychological functioning

2018

Framed from Basic Psychological Needs Theory (Ryan and Deci in American Psychologist 55:68–78; Ryan, Deci, American Psychologist 55:68–78, 2000) and Kagitcibasi’s Autonomous-Related Self Theory (Journal of Cross-Cultural Psychology 36:1–20; Kagitcibasi, Journal of Cross-Cultural Psychology 36:1–20, 2005), the study examined the relationships of adolescents’ satisfaction and frustration of autonomy and relatedness, with (a) adolescents’ perception of mother’s and father’s psychological control and autonomy support, and (b) adolescents’ self-acceptance and anxiety. Participants were 556 adolescents (M = 17.25, SD = 0.92). Path analysis showed more significant associations of autonomy support …

Misurare la soddisfazione lavorativa: costruzione di uno strumento di indagine multidimensionale

2016

Background: Although numerous studies have been done on the topic of job satisfaction, as regards the Italian research, the construction of specific psychometric instruments is lacking. Objectives: The present paper is aimed to develop a scale to measure job satisfaction referring to our cultural context. Methods: Participants were 222 workers (36.5% males, 635% females) with an average age of 3839 years (SD = 10.91). The formulated items were selected from a large item pool on the basis of the evaluation by a group of expert judges, and the item analysis procedure. In order to establish test validity, the following instruments were also administered: Occupational Stress Indicator, Satisfac…