A. Maras | Università degli Studi "La Sapienza" di Roma (original) (raw)

Papers by A. Maras

ABSTRACT The first two sample return missions the NASA Stardust and the ISAS Hayabusa missions ha... more ABSTRACT The first two sample return missions the NASA Stardust and the ISAS Hayabusa missions have captured samples of planetary material that are going to be analysed in terrestrial laboratories Other space missions are planned in the next future to return samples of Mars or asteroids such as the Russian Phobos Soil In this perspective we expect that a limited amount of material will be available for analysis and almost every research planetary Institute would like to participate in this exciting study The ETNA Extra-Terrestrial Nanomaterials Analysis consortium was formed in order to combine high level of expertises from interdisciplinary fields such as planetary science materials science biology and technologies for nanoscale material analysis The ETNA is formed by four research groups that have complementary skills and instrumentation suites The involved Entities are two research Institutes such as the INAF-IFSI and the CNR-ISM and two Universities the Earth Science Department at La Sapienza University and the Physics Department at Roma Tre University One of the main ETNA s goal is the development implementation and application of new analytical technologies for the analysis of extraterrestrial material in laboratory focussing onto material returned from space missions Scientists involved in the project will take advantage of combine well-known analysis techniques available to the Consortium laboratories X-ray diffraction Scanning Electron Microscopy micro-IR and VIS-NIR spectroscopy with the state of

This study aims to focus on cinnabar extraction and trade routes in the Roman Age, when the pigme... more This study aims to focus on cinnabar extraction and trade routes in the Roman Age, when the pigment had its maximum spread, also to clarify if the practice of mixing sources from different quarries is reliable. X-ray powder diffraction (XRPD) has been used as a preliminary test to underline structural variation connected to cinnabar provenance: data from 14 mineralogical samples, coming from 11 different localities, were compared showing that detectable differences exist in terms of unit cell parameters and volume. The results highlight the potentiality of X-ray diffraction for provenance analysis.

Procedia Chemistry, 2013

The aim of the study is to provide, through the characterization of the mortar samples and the re... more The aim of the study is to provide, through the characterization of the mortar samples and the relative raw materials, useful information in order to define the stages of construction, the workers technological and archaeological knowledge. The study is an interdisciplinary approach carried out by different analysis techniques in order to define the mineral-petrographic composition and highlight the differences among the various samples. Mortars are present in all the walls, except dry ones, as a bedding material and as a coating. The mortars may be regarded as markers for excellence, because they must be prepared at the time of their use, during the construction of the masonry, and cannot be re-used after their hardening and socket. Furthermore, the production of mortars in the past depended on the availability of raw materials in situ thus establishing a strong and direct correlation between the origin and use. The chemical and petrographic study of the subtle differences and composition of the mortar makes it possible to use this material as an excellent timeline if the supply of building materials varies over time. Mortars, for these reasons, play two key roles in archaeological survey: an absolutely priority for the correct determination of the contours of Stratigraphic Units; the role of the typological class very representative and very useful for making comparisons between different parts of the building and connecting between them the activities of the individual site.

The association of the most abundant population of meteorites the ordinary chondrites and their p... more The association of the most abundant population of meteorites the ordinary chondrites and their parent bodies through the comparison of their reflected spectra has been a long debate In fact many of the asteroids show reddened spectra when observed in the visible and near-infrared range Gaffey 1976 Cloutis et al 1990 This reddening first observed in lunar mature soils has

Journal of Applied Spectroscopy, 2013

ABSTRACT This paper is a part of the wider project aiming at determining how lighting systems can... more ABSTRACT This paper is a part of the wider project aiming at determining how lighting systems can be standardized and developed, by studying the interaction between light and the constituting materials. To develop this research, an interesting case-study was performed as starting point: realgar photo-degradation. Light transforms realgar in arsenolite and pararealgar, a compound with the same formula of realgar but characterized by a different atomic disposition and color. This study deepens our knowledge of realgar degradation and determines the capacity of inducing degradation by different lamps. The survey was carried out by means of FTIR and micro-Raman spectroscopy. The results confirm literature studies on realgar degradation and suggest that the LED lamp produces less degradation, keeping a high quality of lighting.

Journal of Materials Science, 1998

A study was undertaken to obtain more accurate structural information on poly(p-phenylene sulfide... more A study was undertaken to obtain more accurate structural information on poly(p-phenylene sulfide) (PPS) through Rietveld analysis. A few samples of PPS crystallized in a relatively wide range of physical conditions were selected with the aim of eventually identifying the occurrence of structural modifications induced by the various crystallization procedures. According to the results, the structural modifications are relatively small and essentially confined to variations of the C-S-C angle, for which values within the range 102°-105° were found close to those proposed by Garbarczyk. In particular, the strong influence of the amorphous phase in determining the crystallographic cell dimension was investigated.

The Astrophysical Journal, 2005

The association between the most abundant population of meteorites, the ordinary chondrites, and ... more The association between the most abundant population of meteorites, the ordinary chondrites, and their parent bodies is one of the main topics in the quest to understand the evolution of the solar system. This association is mainly inferred from spectra in visible and near-infrared wavelengths, where many of the asteroids show reddened reflected light curves. The analysis of lunar soils attributed the reddening of the spectra to the presence of nanometer-size metallic particles, and a simulation of micrometeoroid impacts with laser irradiation experiments on terrestrial samples has reproduced this effect and tied it to the vaporization of Fe-bearing silicates. Recently, spacecraft observations have revealed a new mystery in the interpretation of the reddening of S-type asteroids. We have identified an alternative process for surface alteration of airless bodies that can be invoked to solve this mystery through a shock-induced phase transformation of Fe-Ni alloys. These metal phases are usually reported in meteorites but have never been associated with the reddening of the spectra. Here we show, for the first time, atomic force microscopy observations of diffuse nanostructured metal in ordinary chondrites. We also show that the corresponding spectra are unambiguously redder. Subject headings: minor planets, asteroids L118 MORETTI ET AL.

Zeitschrift für Kristallographie, 1998

The structures of cetylpyridiniumammonium bromide (CPyB) and cetylquinuclidinium bromide (CQB), t... more The structures of cetylpyridiniumammonium bromide (CPyB) and cetylquinuclidinium bromide (CQB), two tetraalkylammonium bromide surfactants, are reported. In particular, whereas the structure solution of CPyB was carried out through conventional single-crystal diffractometry, the structure of CQB has been determined by means of powder diffractometry. CPyB crystallizes in

ABSTRACT The first two sample return missions the NASA Stardust and the ISAS Hayabusa missions ha... more ABSTRACT The first two sample return missions the NASA Stardust and the ISAS Hayabusa missions have captured samples of planetary material that are going to be analysed in terrestrial laboratories Other space missions are planned in the next future to return samples of Mars or asteroids such as the Russian Phobos Soil In this perspective we expect that a limited amount of material will be available for analysis and almost every research planetary Institute would like to participate in this exciting study The ETNA Extra-Terrestrial Nanomaterials Analysis consortium was formed in order to combine high level of expertises from interdisciplinary fields such as planetary science materials science biology and technologies for nanoscale material analysis The ETNA is formed by four research groups that have complementary skills and instrumentation suites The involved Entities are two research Institutes such as the INAF-IFSI and the CNR-ISM and two Universities the Earth Science Department at La Sapienza University and the Physics Department at Roma Tre University One of the main ETNA s goal is the development implementation and application of new analytical technologies for the analysis of extraterrestrial material in laboratory focussing onto material returned from space missions Scientists involved in the project will take advantage of combine well-known analysis techniques available to the Consortium laboratories X-ray diffraction Scanning Electron Microscopy micro-IR and VIS-NIR spectroscopy with the state of

This study aims to focus on cinnabar extraction and trade routes in the Roman Age, when the pigme... more This study aims to focus on cinnabar extraction and trade routes in the Roman Age, when the pigment had its maximum spread, also to clarify if the practice of mixing sources from different quarries is reliable. X-ray powder diffraction (XRPD) has been used as a preliminary test to underline structural variation connected to cinnabar provenance: data from 14 mineralogical samples, coming from 11 different localities, were compared showing that detectable differences exist in terms of unit cell parameters and volume. The results highlight the potentiality of X-ray diffraction for provenance analysis.

Procedia Chemistry, 2013

The aim of the study is to provide, through the characterization of the mortar samples and the re... more The aim of the study is to provide, through the characterization of the mortar samples and the relative raw materials, useful information in order to define the stages of construction, the workers technological and archaeological knowledge. The study is an interdisciplinary approach carried out by different analysis techniques in order to define the mineral-petrographic composition and highlight the differences among the various samples. Mortars are present in all the walls, except dry ones, as a bedding material and as a coating. The mortars may be regarded as markers for excellence, because they must be prepared at the time of their use, during the construction of the masonry, and cannot be re-used after their hardening and socket. Furthermore, the production of mortars in the past depended on the availability of raw materials in situ thus establishing a strong and direct correlation between the origin and use. The chemical and petrographic study of the subtle differences and composition of the mortar makes it possible to use this material as an excellent timeline if the supply of building materials varies over time. Mortars, for these reasons, play two key roles in archaeological survey: an absolutely priority for the correct determination of the contours of Stratigraphic Units; the role of the typological class very representative and very useful for making comparisons between different parts of the building and connecting between them the activities of the individual site.

The association of the most abundant population of meteorites the ordinary chondrites and their p... more The association of the most abundant population of meteorites the ordinary chondrites and their parent bodies through the comparison of their reflected spectra has been a long debate In fact many of the asteroids show reddened spectra when observed in the visible and near-infrared range Gaffey 1976 Cloutis et al 1990 This reddening first observed in lunar mature soils has

Journal of Applied Spectroscopy, 2013

ABSTRACT This paper is a part of the wider project aiming at determining how lighting systems can... more ABSTRACT This paper is a part of the wider project aiming at determining how lighting systems can be standardized and developed, by studying the interaction between light and the constituting materials. To develop this research, an interesting case-study was performed as starting point: realgar photo-degradation. Light transforms realgar in arsenolite and pararealgar, a compound with the same formula of realgar but characterized by a different atomic disposition and color. This study deepens our knowledge of realgar degradation and determines the capacity of inducing degradation by different lamps. The survey was carried out by means of FTIR and micro-Raman spectroscopy. The results confirm literature studies on realgar degradation and suggest that the LED lamp produces less degradation, keeping a high quality of lighting.

Journal of Materials Science, 1998

A study was undertaken to obtain more accurate structural information on poly(p-phenylene sulfide... more A study was undertaken to obtain more accurate structural information on poly(p-phenylene sulfide) (PPS) through Rietveld analysis. A few samples of PPS crystallized in a relatively wide range of physical conditions were selected with the aim of eventually identifying the occurrence of structural modifications induced by the various crystallization procedures. According to the results, the structural modifications are relatively small and essentially confined to variations of the C-S-C angle, for which values within the range 102°-105° were found close to those proposed by Garbarczyk. In particular, the strong influence of the amorphous phase in determining the crystallographic cell dimension was investigated.

The Astrophysical Journal, 2005

The association between the most abundant population of meteorites, the ordinary chondrites, and ... more The association between the most abundant population of meteorites, the ordinary chondrites, and their parent bodies is one of the main topics in the quest to understand the evolution of the solar system. This association is mainly inferred from spectra in visible and near-infrared wavelengths, where many of the asteroids show reddened reflected light curves. The analysis of lunar soils attributed the reddening of the spectra to the presence of nanometer-size metallic particles, and a simulation of micrometeoroid impacts with laser irradiation experiments on terrestrial samples has reproduced this effect and tied it to the vaporization of Fe-bearing silicates. Recently, spacecraft observations have revealed a new mystery in the interpretation of the reddening of S-type asteroids. We have identified an alternative process for surface alteration of airless bodies that can be invoked to solve this mystery through a shock-induced phase transformation of Fe-Ni alloys. These metal phases are usually reported in meteorites but have never been associated with the reddening of the spectra. Here we show, for the first time, atomic force microscopy observations of diffuse nanostructured metal in ordinary chondrites. We also show that the corresponding spectra are unambiguously redder. Subject headings: minor planets, asteroids L118 MORETTI ET AL.

Zeitschrift für Kristallographie, 1998

The structures of cetylpyridiniumammonium bromide (CPyB) and cetylquinuclidinium bromide (CQB), t... more The structures of cetylpyridiniumammonium bromide (CPyB) and cetylquinuclidinium bromide (CQB), two tetraalkylammonium bromide surfactants, are reported. In particular, whereas the structure solution of CPyB was carried out through conventional single-crystal diffractometry, the structure of CQB has been determined by means of powder diffractometry. CPyB crystallizes in