The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Norberto Roveri - One of the best experts on this subject based on the ideXlab platform.
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asbestos health hazard a spectroscopic study of synthetic geoinspired fe doped Chrysotile
Journal of Hazardous Materials, 2009Co-Authors: Elisabetta Foresti, C Rinaudo, Isidoro Giorgio Lesci, E Fornero, Tommaso Zuccheri, Norberto RoveriAbstract:The Chrysotile fibres toxicity appears correlated to the redox activity of iron present in the Chrysotile structure. In fact the generation of reactive oxygen species and other radicals appears catalyzed by iron ions and closely related to Fe ions organization in specific crystallographic sites having a capability to activate free radical generation. The Fe substitution to Mg and/or Si in the Chrysotile structure appears important for asbestos health hazard investigation. Infrared and Raman spectroscopic analyses have been utilized to investigate Mg and/or Si ions replacement by Fe ions in Chrysotile structure as a function of the Fe doping extent. Geoinspired synthetic Chrysotile at different Fe doping extents has been obtained as unique phase by hydrothermal reaction in the presence or not of metallic Fe in the synthetic environment. The results highlight that Fe can replace both Mg and Si, differently modifying the Chrysotile structure as a function of the Fe doping extent and the Fe doping process. The contemporary iron substitution into the octahedral and tetrahedral sheets reveals an appreciable increase of the dehydroxylation temperature which occurs at higher temperature than for iron-free sample. The results highlight the role of Fe substitution in the asbestos structure influencing the health hazard of biological systems.
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morphological and chemical physical characterization of fe doped synthetic Chrysotile nanotubes
Advanced Functional Materials, 2005Co-Authors: Elisabetta Foresti, Michael F Hochella, Hiromi Kornishi, Isidoro Giorgio Lesci, Andrew S Madden, Norberto Roveri, Huifang XuAbstract:In the field of thin-layer-structured inorganic nanotubes, morphological, structural, and chemical/physical modifications induced in synthetic stoichiometric Chrysotile nanotubes have been evaluated as a function of the extent of Fe doping. Fe-doped synthetic Chrysotile nanocrystals have been obtained in the range from 0.29 wt.-% up to 1.37 wt.-% Fe. A partial Fe replacement for Si and Mg has been observed through the modification of Fourier-transform infrared (FTIR) absorption bands. FTIR spectroscopic, X-ray diffraction, and thermogravimetric analyses provide evidence for Fe inclusion into the Chrysotile crystal structure, in both octahedral and tetrahedral sites, which induces a flattening of the curved brucite-like layers in the stoichiometric Chrysotile. Further characterization by morphological analysis (scanning electron microscopy, transmission electron microscopy, and atomic force microscopy) has revealed the effect of Fe doping on the aggregation of Chrysotile nanotubes. The results appear interesting in light of the proposed possibilities of synthetic Chrysotile fibers to represent an alternative to carbon nanotubes for innovative technological applications.
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tubular shaped stoichiometric Chrysotile nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
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Tubular‐Shaped Stoichiometric Chrysotile Nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
Elisabetta Foresti - One of the best experts on this subject based on the ideXlab platform.
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asbestos health hazard a spectroscopic study of synthetic geoinspired fe doped Chrysotile
Journal of Hazardous Materials, 2009Co-Authors: Elisabetta Foresti, C Rinaudo, Isidoro Giorgio Lesci, E Fornero, Tommaso Zuccheri, Norberto RoveriAbstract:The Chrysotile fibres toxicity appears correlated to the redox activity of iron present in the Chrysotile structure. In fact the generation of reactive oxygen species and other radicals appears catalyzed by iron ions and closely related to Fe ions organization in specific crystallographic sites having a capability to activate free radical generation. The Fe substitution to Mg and/or Si in the Chrysotile structure appears important for asbestos health hazard investigation. Infrared and Raman spectroscopic analyses have been utilized to investigate Mg and/or Si ions replacement by Fe ions in Chrysotile structure as a function of the Fe doping extent. Geoinspired synthetic Chrysotile at different Fe doping extents has been obtained as unique phase by hydrothermal reaction in the presence or not of metallic Fe in the synthetic environment. The results highlight that Fe can replace both Mg and Si, differently modifying the Chrysotile structure as a function of the Fe doping extent and the Fe doping process. The contemporary iron substitution into the octahedral and tetrahedral sheets reveals an appreciable increase of the dehydroxylation temperature which occurs at higher temperature than for iron-free sample. The results highlight the role of Fe substitution in the asbestos structure influencing the health hazard of biological systems.
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morphological and chemical physical characterization of fe doped synthetic Chrysotile nanotubes
Advanced Functional Materials, 2005Co-Authors: Elisabetta Foresti, Michael F Hochella, Hiromi Kornishi, Isidoro Giorgio Lesci, Andrew S Madden, Norberto Roveri, Huifang XuAbstract:In the field of thin-layer-structured inorganic nanotubes, morphological, structural, and chemical/physical modifications induced in synthetic stoichiometric Chrysotile nanotubes have been evaluated as a function of the extent of Fe doping. Fe-doped synthetic Chrysotile nanocrystals have been obtained in the range from 0.29 wt.-% up to 1.37 wt.-% Fe. A partial Fe replacement for Si and Mg has been observed through the modification of Fourier-transform infrared (FTIR) absorption bands. FTIR spectroscopic, X-ray diffraction, and thermogravimetric analyses provide evidence for Fe inclusion into the Chrysotile crystal structure, in both octahedral and tetrahedral sites, which induces a flattening of the curved brucite-like layers in the stoichiometric Chrysotile. Further characterization by morphological analysis (scanning electron microscopy, transmission electron microscopy, and atomic force microscopy) has revealed the effect of Fe doping on the aggregation of Chrysotile nanotubes. The results appear interesting in light of the proposed possibilities of synthetic Chrysotile fibers to represent an alternative to carbon nanotubes for innovative technological applications.
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tubular shaped stoichiometric Chrysotile nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
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Tubular‐Shaped Stoichiometric Chrysotile Nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
Isidoro Giorgio Lesci - One of the best experts on this subject based on the ideXlab platform.
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asbestos health hazard a spectroscopic study of synthetic geoinspired fe doped Chrysotile
Journal of Hazardous Materials, 2009Co-Authors: Elisabetta Foresti, C Rinaudo, Isidoro Giorgio Lesci, E Fornero, Tommaso Zuccheri, Norberto RoveriAbstract:The Chrysotile fibres toxicity appears correlated to the redox activity of iron present in the Chrysotile structure. In fact the generation of reactive oxygen species and other radicals appears catalyzed by iron ions and closely related to Fe ions organization in specific crystallographic sites having a capability to activate free radical generation. The Fe substitution to Mg and/or Si in the Chrysotile structure appears important for asbestos health hazard investigation. Infrared and Raman spectroscopic analyses have been utilized to investigate Mg and/or Si ions replacement by Fe ions in Chrysotile structure as a function of the Fe doping extent. Geoinspired synthetic Chrysotile at different Fe doping extents has been obtained as unique phase by hydrothermal reaction in the presence or not of metallic Fe in the synthetic environment. The results highlight that Fe can replace both Mg and Si, differently modifying the Chrysotile structure as a function of the Fe doping extent and the Fe doping process. The contemporary iron substitution into the octahedral and tetrahedral sheets reveals an appreciable increase of the dehydroxylation temperature which occurs at higher temperature than for iron-free sample. The results highlight the role of Fe substitution in the asbestos structure influencing the health hazard of biological systems.
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morphological and chemical physical characterization of fe doped synthetic Chrysotile nanotubes
Advanced Functional Materials, 2005Co-Authors: Elisabetta Foresti, Michael F Hochella, Hiromi Kornishi, Isidoro Giorgio Lesci, Andrew S Madden, Norberto Roveri, Huifang XuAbstract:In the field of thin-layer-structured inorganic nanotubes, morphological, structural, and chemical/physical modifications induced in synthetic stoichiometric Chrysotile nanotubes have been evaluated as a function of the extent of Fe doping. Fe-doped synthetic Chrysotile nanocrystals have been obtained in the range from 0.29 wt.-% up to 1.37 wt.-% Fe. A partial Fe replacement for Si and Mg has been observed through the modification of Fourier-transform infrared (FTIR) absorption bands. FTIR spectroscopic, X-ray diffraction, and thermogravimetric analyses provide evidence for Fe inclusion into the Chrysotile crystal structure, in both octahedral and tetrahedral sites, which induces a flattening of the curved brucite-like layers in the stoichiometric Chrysotile. Further characterization by morphological analysis (scanning electron microscopy, transmission electron microscopy, and atomic force microscopy) has revealed the effect of Fe doping on the aggregation of Chrysotile nanotubes. The results appear interesting in light of the proposed possibilities of synthetic Chrysotile fibers to represent an alternative to carbon nanotubes for innovative technological applications.
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tubular shaped stoichiometric Chrysotile nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
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Tubular‐Shaped Stoichiometric Chrysotile Nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
Romain Lafay - One of the best experts on this subject based on the ideXlab platform.
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dissolution reprecipitation and self assembly of serpentine nanoparticles preceding Chrysotile formation insights into the structure of proto serpentine
American Mineralogist, 2016Co-Authors: Romain Lafay, Alejandro Fernandezmartinez, German Monteshernandez, Anne Line Auzende, Agnieszka PoulainAbstract:Any poorly crystalline serpentine-type mineral with a lack of recognizable textural or diffraction features for typical serpentine varieties (i.e., chryotile, lizardite, and antigorite) is usually referred to as proto-serpentine. The formation of the so-called proto-serpentine seems ubiquitous in serpentinization reactions. It is related to dissolution-precipitation of strongly reactive particles prior to true serpentine formation (e.g., in veins where both Chrysotile and proto-serpentine are described). However, the structural characteristics of proto-serpentine and its relation with serpentine crystalline varieties remain unclear. In this study a model describing the transformation from proto-serpentine to Chrysotile is presented based on experimental Chrysotile synthesis using thermogravimetric analyses, transmission electron microscopy, and high-energy X-ray diffraction with pair distribution function analyses. The combination of the high-resolution TEM and high-energy X-ray diffraction enables to resolve the local order of neo-formed particles and their structuration processes occurring during pure Chrysotile formation (i.e., during the first three hours of reaction). The formation of individual nanotubes is preceded by the formation of small nanocrystals that already show a Chrysotile short-range order, forming porous anastomosing features of hydrophilic crystallites mixed with brucite. This is followed by a hierarchical aggregation of particles into a fiber-like structure. These flake-like particles subsequently stack forming concentric layers with the Chrysotile structure. Finally, the individualization of Chrysotile nanotubes with a homogeneous distribution of diameter and lengths (several hundreds of nanometer in length) is observed. The competitive precipitation of brucite and transient serpentine during incipient serpentinization reaction indicates that both dissolution-precipitation and serpentine-particle aggregation processes operate to form individual Chrysotile. This study sheds light into mineralization processes and sets a first milestone toward the identification of the factors controlling polymorph selection mechanisms in this fascinating system.
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nucleation and growth of Chrysotile nanotubes in h2sio3 mgcl2 naoh medium at 90 to 300 c
Chemistry: A European Journal, 2013Co-Authors: Romain Lafay, German Monteshernandez, Emilie Janots, Rodica Chiriac, Nathaniel Findling, Francois TocheAbstract:Herein, we report new in- sights into the nucleation and growth processes of Chrysotile nanotubes by using batch and semi-continuous ex- periments. For the synthesis of this highly carcinogenic material, the influ- ences of temperature (90, 200, and 3008C), Si/Mg molar ratio, and reac- tion time were investigated. From the semi-continuous experiments (i.e., sam- pling of the reacting suspension over time) and solid-state characterization of the collected samples by XRPD, TGA, FTIR spectroscopy, and FESEM, three main reaction steps were identified for Chrysotile nuclea- tion and growth at 3008C: 1) formation of the proto-serpentine precursor within the first 2 h of the reaction, ac- companied by the formation of brucite and residual silica gel; 2) spontaneous nucleation and growth of Chrysotile be- tween about 3 and 8 h reaction time, through a progressive dissolution of the proto-serpentine, brucite, and residual silica gel; and 3) Ostwald ripening growth of Chrysotile from 8 to 30 h re- action time, as attested to by BET and FESEM measurements. Complementa- ry results from batch experiments con- firmed a significant influence of the re- action temperature on the kinetics of Chrysotile formation. However, FESEM observations revealed some formation of Chrysotile nanotubes at low temperatures (908C) after 14 days of reaction. Finally, doubling the Si/Mg molar ratio promoted the precipitation of pure smectite (stevensite-type) under the same P (8.2 MPa)/T (3008C)/pH (13.5) conditions.
Alessandro F. Gualtieri - One of the best experts on this subject based on the ideXlab platform.
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The crystal structure of mineral fibres: 1. Chrysotile
Periodico Di Mineralogia, 2016Co-Authors: Simone Pollastri, Andrea Cavallo, Natale Perchiazzi, Marco Lezzerini, Jasper Rikkert Plaisier, Maria Chiara Dalconi, Nicola Bursi Gandolfi, Alessandro F. GualtieriAbstract:This work reports the result s of the structural study of three representative Chrysotile samples of different provenance (Canadian UICC, and Italian Balangero and Valmalenco) . Chemical composition was determined using EMPA and TG data. An innovative wet cryo-milling procedure was used to powder the resistant-to-abrasion Chrysotile fibres. X-ray powder diffraction patterns were collected using both conventional and non-conventional sources. Collected data were used for Rietveld structural refinements and results were compared with available literature data. The three samples display similar structure models, although small differences were detected in the position of the oxygen atoms. Both the structural refinements and spectroscopic investigations confirms that Fe 2+ and Fe 3+ atoms in Chrysotile are located in the octahedral cavities only, substituting for Mg 2+ . Regarding the atom coordinates, UICC Chrysotile is the more similar to the model reported by Falini et al. (2004). About the lattice parameters, the Valmalenco Chrysotile is the more similar, if compared with the Balangero and UICC, to both the model proposed by Whittaker (1956a,b) and Falini et al. (2004) . This work is intended as a basis for subsequent studies aimed at understanding the potential toxicity of these mineral fibres.
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The zeta potential of mineral fibres
Journal of Hazardous Materials, 2014Co-Authors: Simone Pollastri, Andrea Cavallo, Alessandro F. Gualtieri, Magdalena Lassinantti Gualtieri, Miriam Hanuskova, Giovanni GaudinoAbstract:Abstract For the first time, the zeta (ξ) potential of pathogenic mineral fibres (Chrysotiles, amphiboles and erionite) was systematically investigated to shed light on the relationship between surface reactivity and fibre pathogenicity. A general model explaining the zeta potential of Chrysotile, amphiboles and erionite has been postulated. In double distilled water, Chrysotiles showed positive values while crocidolite and erionite showed negative values. In contact with organic solutions, all fibres exhibited negative values of zeta potential. The decrease of the surface potential is deemed to be a defensive chemical response of the macrophage cells to minimize hemolytic damage. Negatively charged surfaces favour the binding of collagen and redox activated Fe-rich proteins, to form the so-called asbestos bodies and prompt the formation of HO via the reaction with peroxide (H2O2 + e− → HO + HO−). An additional mechanism accounting for higher carcinogenicity is possibly related to the Ca2+ sequestration by the fibres with surface negative potential, impairing the mitochondrial apoptotic pathway. It was also found that with a negative zeta potential, the attractive forces prevailed over repulsions and favoured processes such as agglomeration responsible of a tumorigenic chronic inflammation.
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tubular shaped stoichiometric Chrysotile nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.
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Tubular‐Shaped Stoichiometric Chrysotile Nanocrystals
Chemistry: A European Journal, 2004Co-Authors: Giuseppe Falini, Alessandro F. Gualtieri, Elisabetta Foresti, Isidoro Giorgio Lesci, Massimo Gazzano, Matteo Leoni, Norberto RoveriAbstract:Stoichiometric Chrysotile tub- ular nanocrystals have been synthe- sized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular inter- actions between Chrysotile, the most utilized asbestos, and biological sys- tems. Chrysotile nanocrystals have been synthesized under controlled hy- drothermal conditions, and have been characterized by chemical, morphologi- cal, structural, spectroscopic and micro- calorimetric analyses. They show a con- stant ™cylinder-in-cylinder∫ morpholo- gy constituted by two or three concen- tric subunits. Each single nanocrystal has a tubular shape of about 49 1n m in outer maximum diameter, and a hollow core of about 7 1 nm. Struc- tural investigation carried out on an X- ray powder pattern allowed to improve the structural model proposed for Chrysotile mineral samples. Synthetic Chrysotile crystallizes in the monoclinic Cc space group with a = 0.5340(1) nm, b = 0.9241(1) nm, and c = 1.4689(2) nm, b = 93.66(3)8.