The influence of affective factors on time perception

Several studies have suggested that both affective valence and arousal affect the perception of time. How-ever, in previous experiments these two affective dimensions were not systematically controlled. In the present study, a set of emotional slides rated for valence and arousal (International Affective Picture System) were projected to two groups of subjects for 2, 4 and 6 sec. One group estimated the duration on an analog scale and a second group reproduced the interval by pushing a button. Heart rate and skin conductance responses were also recorded. A highly significant valence by arousal interaction affected duration judg-ments. For low arousal stimuli, the duration of negative slides was judged relatively shorter than the duration of positive slides. For high arousal stimuli, the duration of negative slides was judged longer than the dura-tion of positive slides. These results are interpreted within a model of action tendency, in which the level of arousal controls two different motivational mechanisms, one emotional and the other attentional

Aluminium distribution in an Earth’s non–primitive lower mantle

The aluminium incorporation mechanism of perovskite was explored by means of quantum mechanics in combination with equilibrium/off-equilibrium thermodynamics under the pressure-temperature conditions of the Earth’s lower mantle (from 24 to 80 GPa). Earth’s lower mantle was modelled as a geochemically non-primitive object because of an enrichment by 3 wt% of recycled crustal material (MORB component). The compositional modelling takes into account both chondrite and pyrolite reference models. The capacity of perovskite to host Al was modelled through an Al2O3 exchange process in an unconstrained Mg-perovskite+Mg-Al-perovskite+free-Al2O3(corundum) system. Aluminium is globally incorporated principally via an increase in the amount of Al bearing perovskite [Mg-Al-pv(80 GPa)/Mg-Al-pv(24 GPa)1.17], rather than by an increase in the Al2O3 content of the average chemical composition which changes little (0.11-0.13, mole fraction of Al2O3) and tends to decrease in Al. The Al2O3 distribution in the lower mantle was described through the probability of the occurrence of given compositions of Al bearing perovskite. The probability of finding Mg-Al-perovskite is comparable to Mg-perovskites. Perovskite with Al2O3 mole fraction up to 0.15 has an occurrence probability of ~28% at 24 GPa, increasing up to ~43% at 80 GPa; on the contrary, perovskite compositions in the range 0.19-0.30 Al2O3 mole fraction drop their occurrence probability from 9.8 to 2.0%, over the same P-range. In light of this, the distribution of Al in the lower mantle shows that, among the possible Al bearing perovskite phases, the (Mg0.89Al0.11)(Si0.89Al0.11)O3 composition is the likeliest, providing from 5 to 8% of the bulk perovskite in the pressure range from 24 to 80 GPa. The occurrence of the most Al rich composition, i.e. (Mg0.71Al0.29)(Si0.71Al0.29)O3, is a rare event (probability of occurrence < 1.7%). This study predicts that perovskite may globally host Al2O3 in terms of 4.3 and 4.8 wt% (with respect to the non-primitive lower mantle mass), thus accounting for ~ 90% and 100% of the bulk Al2O3 estimated in the framework of pyrolite and chondrite reference models, respectively. A calcium-ferrite type phase (on the MgAl2O4-NaAlSiO4 join) seems to be the only candidate that can compensate for the 10% gap of the perovskite Al incorporation capacity, in the case of a pyrolite non-primitive lower mantle model

The effects of MgO, Na2O and SO3 on industrial clinkering process: phase composition, polymorphism, microstructure and hydration, using a multidisciplinary approach

Preprint publicado en: Materials Characterization Volume 155, September 2019, 109809The present investigation deals with how minor elements (their oxides: MgO, Na2O and SO3) in industrial kiln feeds affect (i) chemical reactions upon clinkering, (ii) resulting phase composition and microstructure of clinker, (iii) hydration process during cement production. Our results show that all these points are remarkably sensitive to the combination and interference effects between the minor chemical species mentioned above. Upon clinkering, all the industrial raw meals here used exhibit the same formation temperature and amount of liquid phase. Minor elements are preferentially hosted by secondary phases, such as periclase. Conversely, the growth rate of the main clinker phases (alite and belite) is significantly affected by the nature and combination of minor oxides. MgO and Na2O give a very fast C3S formation rate at T > 1450 K, whereas Na2O and SO3 boost C2S After heating, if SO3 occurs in combination with MgO and/or Na2O, it does not inihibit the C3S crystallisation as expected. Rather, it promotes the stabilisation of M1-C3S, thus indirectly influencing the aluminate content, too. MgO increseases the C3S amount and promotes the stabilisation of M3-C3S, when it is in combination with Na2O. Na2O seems to be mainly hosted by calcium aluminate structure, but it does not induce the stabilisation of the orhtorhombic polymorph, as supposed to occur. Such features play a key role in predicting the physicalmechanical performance of a final cement (i.e. rate of hydration and hardening) when used as a bulding material.The present study has been partly funded by the project PRIN 2017 (2017L83S77), of the Italian Ministry for Education, University and Research (MIUR)