12 research outputs found

    Spiro-derivatives as hole transporting materials for improving the performance of perovskite solar cells

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    The Sun is the most powerful source of energy in the Earth's solar system, which, in part, can be exploited by all the inhabitants of the Earth. The optimal exploitation of the fraction that arrives on earth is, undoubtedly, among the most important challenges nowadays of science. To convert sun light into chemical energy, the first silicon-based device Photovoltaic (PV) solar cells, prepared by Chapin in 1954 exhibiting an efficiency around 6% [1,2] used different semiconducting materials (inorganic, organic, molecular, polymeric, hybrids, quantum dots, etc.). Today the most promising technology to replace/complement crystalline silicon PV [3] are the Perovskites solar cells (PSCs) that emerged since 2009, achieving efficiencies of ~26 %. These results were obtained using commercially available spiro-OMeTAD as hole-transporting material (HTM) that are expensive materials due to its difficult purification and multi-step synthetic protocols (in harsh conditions) which limits its future use in large-scale applications. Considering the negative aspects related to the industrial production of the spiro-OMeTAD, we synthesized some intermediates necessary for the subsequent synthesis of four spiro-derivatives. Excellent results were obtained with some derivatives based on electron-rich spiranic scaffolds [4], synthesized by the Buchwald-Hartwig reaction, carried out in toluene. In this way it was possible to obtain the spiro-PTZ functionalized, by making structural modifications to the previously obtained derivatives, the yield of this synthesis was around 21%. The compounds obtained were incorporated into perovskite solar cells providing efficiencies higher than the standard used (spiroOMeTAD). The devices have been tested under illumination and have shown good stability over time

    A Short Review of Simple Analytical Methods for the Evaluation of PAHs and PAEs as Indoor Pollutants in House Dust Samples

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    Studies on indoor air quality are indispensable when considering that people spend approximately 85% of their time in confined environments. This short review mostly takes into consideration research that uses passive samplers to evaluate the quality of indoor environments (houses, school, cars, etc.). This short review summarizes most analytical methods to detect and quantify PAHs and PAEs in house dust used as a passive sampler. The objective of house dust analysis is to identify the presence, amount and distribution of specific hazardous substances in confined spaces and, if possible, to identify their sources. Household dust and the compounds present in it can enter the human body by inhalation, non-food ingestion and absorption through the skin. The observed differences in concentrations of house dust may also indicate important differences in the chemical and physical nature of pollutants caused by air filtration and absorption during the migration of ambient air into the indoor environment

    A reappraisal of the 1978 Ferruzzano earthquake (southern Italy) from new estimates of hypocenter location and moment tensor inversion

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    The March 11th, 1978 Ferruzzano earthquake is the most recent moderate-to-major earthquake occurred in the southern Calabrian region (southern Italy), one among the highest seismic risk areas of the whole Mediterranean. Previous information available from the literature on the 1978 earthquake is quite contrasting and not well framed in the regional seismotectonic scenario. In the present study we selected and digitized analog seismograms coming from stations of the Euro-Mediterranean region to invert for the deviatoric seismic moment tensor through a time-domain algorithm properly implemented to analyze data recorded before the advent of the digital era. Moreover, we estimated a new hypocentral location by using original bulletin data and a non-linear probabilistic earthquake location technique working with 3D velocity models. The quality and stability of the obtained results, both for hypocenter location and moment tensor inversion, were accurately checked by several inversion tests. Our results indicate that the 1978 earthquake (i) occurred westward and at a shallower depth respect to previous hypocenter locations, (ii) is characterized by a ca. N-S trending normal faulting mechanism and (iii) has a moment magnitude of 4.7, thus suggesting an overestimate of previous evaluations. This study furnishes new information on the 1978 Ferruzzano earthquake allowing to better frame it in the regional seismotectonic scenario and also proves that the time-domain waveform inversion algorithm applied to digitized old seismograms is capable to successfully invert also M w < 5 earthquakes. The obtained results pave the way for future analyses of the early instrumental seismicity potentially capable to furnish new constraints to local and regional seismotectonic modeling.Published34-443T. Sorgente sismica4T. SismicitĂ  dell'Italia6T. Studi di pericolositĂ  sismica e da maremotoJCR Journa

    Integration of geological and geophysical data for re-evaluation of local seismic hazard and geological structure: the case study of Rometta, Sicily (Italy)

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    The village of Rometta, northern-eastern Sicily (Southern Italy), experienced severe damage during the most energetic earthquakes that occurred in eastern Sicily and southern Calabria in the last centuries. Geological maps indicate that Rometta primarily lies on a stiff plate of Upper Pliocene – Lower Pleistocene calcarenites and only to minor extent on Middle Pleistocene overlying clays. Rometta represents an interesting case study for site response investigation because of the apparent mismatch between the currently available geological knowledge and the level of damage caused by historical seismic events. The local seismic response has been investigated through a grid of 64 single-station measurements of ambient seismic noise by the Horizontal to Vertical Noise Spectral Ratio technique (H/V). Also, phase velocity dispersion curves from seismic array through the Extended Spatial Auto-Correlation method were analyzed. The H/V curves obtained show a ubiquitous frequency peak between 0.5 Hz and 0.9 Hz due to the deep interface between the metamorphic substrate and sedimentary sequence, and a secondary peak in the 2.5–15 Hz interval in most of the measurement points that may be related to a larger extent of the clay outcrops with respect to what is already known from geological investigations. Joint inversion of dispersion and H/V curves was also performed in order to obtain the velocity profile. Results acquired through the combined use of geophysical methods furnished useful information for seismic hazard evaluation where surface geology is not clearly visible because of urbanization and vegetation cover, thus suggesting that a wide extent of clays may reasonably be the cause of past earthquake damage distribution.

    Ambient noise measurements for preliminary microzoning studies in the city of Messina, Sicily

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    On December 28th 1908 the city of Messina was destroyed by one of the most catastrophic Italian earthquakes of the last centuries (Mw=7.1, I = XI) which caused more than 60000 deaths and destruction in many localities of Sicily and Calabria. In this study we present the results of more than 100 seismic ambient noise measurements carried out in the framework of the first massive seismic site response survey performed in the city of Messina. Starting from geological information and historical reports reconstructing the damage scenario of the 1908 event, we have identified several sites particularly interesting for seismic response investigations. This extensive survey allowed us to evaluate the fundamental resonance frequency for each investigated site and to identify the areas prone to site amplification. Measurements have been performed by using 3-component velocimeter, Micromed Tromino, and the collected dataset has been processed by applying the Horizontal-to-Vertical Spectral Ratio technique. For each investigated site we provide the fundamental resonance frequency and a preliminary information on the metamorphic bedrock depth. The massive dataset collected and the results obtained will be useful for the seismic microzonation of the urban territory of Messina.

    Long-term earthquake potential of active faults by using coastal and off-shore geological and morphological indicators

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    Seismogenic fault models and active deformation ones coupled with models of both earthquake rate and earthquake probability were recently used in a time-independent modelling. The integration of models allows to estimates the magnitude, location, and likelihood of potentially damaging earthquake ruptures in regions with high natural seismic hazard. Improvements of these models imply the recognition of the spatial geometry of the larger, active faults, deemed to be the source of the most damaging future earthquakes. However, identifying active faults and calculating their geologic slip rates for deriving earthquake rates are not easy tasks in regions inaccessible to direct field studies like active offshore areas. To improve the ability to define seismogenic fault models and active deformation models in offshore areas, we aim to develop a geophysical/geological method that allows to (a) identify the spatial geometry of active faults and fault systems in coastal areas, and (b) deduce the average long-term slip rates and recurrence interval, displacement per event, and elapsed time since the last event along the fault plane. The approach consists of innovative combination of geological and geophysical dataset, sampling methodology and GIS based on morphometric analysis. Preliminary results of this multidisciplinary approach applied to the coastal area of north Sicily document active deformation in an on-land sector of the Sicilian Maghrebian Chain and in its off-shore prolongation. Here we present results concerning the Palermo-Termini Imerese coastal sector based on a combination of: 1) structural data, 2) high-resolution reflection seismic data, 3) time series of GNSS data of the permanent stations of Palermo, Partinico, Prizzi, and Termini compared to the IGS station of Noto, 4) morphometric analysis of high-resolution digital elevation data for the hydrographic basins of the Oreto, Eleuterio, Milicia, San Leonardo, Torto and Imera Settentrionale rivers, and 5) seismological data. In the area of the Capo Zafferano promontory, Pleistocene conglomerates and grainstones are affected by recent tectonic deformation. In particular, at two sites near the village of Porticello we observed two sets of N-S to NNW-SSE and NE-SW striking deformation bands. Both sets have an almost vertical dip and show mutual cross-cutting relationships, suggesting their contemporaneous development. The N-S to NNW-SSE striking set shows left-lateral strike slip kinematic. At place, the deformation bands affect also Upper Pleistocene (Tyrrhenian) bio-calcarenites. In the off-shore, a number of seismic units, bounded by unconformities, were identified on seismic lines. The unit of inferred late Pleistocene age appears to be folded and faulted. Faults generally have an inclination of ca. 50°, small displacements up to 10 m and are sealed by the unit of inferred post-LGM age. Only a limited number of these faults are observed moving ca. 3 km offshore towards the NE. The average values of the velocity vectors obtained for the Palermo, Partinico, Prizzi, and Termini Imerese stations are 4.55, 2.97, 2.96, and 2.15 mm/yr, respectively. The direction of the velocity vectors for all stations is oriented towards the IGS reference station of Noto. The relative displacements of the Termini Imerese, Partinico and Prizzi stations respect to Palermo station are most equal to 0.5 mm/yr. Also, the directions of vectors suggest a clockwise rotation. The drainage network analysis highlights that the trunk streams of Eleuterio and San Leonardo drainage networks are asymmetric towards SE and the absolute asymmetry are ~ 3 and ~ 2 km, respectively. On the contrary, the trunk streams of the Milicia, Torto and Imera Settentrionale rivers are asymmetric towards W-NW with an asymmetry ranging from 3.5 up to 4 km. The Oreto stream does not show any evidence of lateral shift. Hypsometric analysis shows two types of statistical distributions of elevation classes. The latter have a bi-modal distribution for the Eleuterio, Oreto and Torto basins while uni-modal for the Milicia and San Leonardo basins. Values of the hypsometric integral are ~ 0.4 for the Milicia, San Leonardo and Torto basins, ~ 0.5 for the Eleuterio basin and 0.35 for the Oreto basin. The study area has been struck in the past centuries by several significant earthquakes of I0 ≥ 6. Mainly low-to-moderate magnitude seismicity, instead, occurred in this sector in the more recent times, showing highest earthquake concentration in the Tyrrhenian off-shore of the study area with respect to the onshore sector. To furnish a first constraint on seismogenic sources lying in this area, we performed hypocenter location and focal mechanism computation of the seismicity that occurred in the last thirty years. Then, we jointly evaluated data and information coming from historical seismicity with the results obtained by the geophysical, geological, and seismological analyses performed in order to better characterize the possible seismogenic sources present in the study region
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