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Yeghis Keheyan

Università degli Studi "La Sapienza" di Roma, Chemistry, Department Member

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I am a retired prime researcher from National Resarch Council (CNR) Italy but continue to work as volunteer in fields of cultural heritage, nuclear chemistry and astrochemistry

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American University of Beirut

University of California, Santa Barbara

University of British Columbia

University College Cork

Sean W . Anthony

Ohio State University

Alejandra B Osorio

Wellesley College

Kansas State University

Ucla

University of Florida

The Australian National University

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Papers by Yeghis Keheyan

A New Painting Fragment from Erebuni and an Overview of Urartian Wall Paintings

Over the Mountains and Far Away: Studies in Near Eastern history and archaeology presented to Mirjo Salvini on the occasion of his 80th birthday, 2019

Spectroscopic Study of an Armenian Manuscript from Biblioteca Universitaria

The manuscript of Edessa or ms. 3290, a XVIII century Armenian manuscript kept at Biblioteca Univ... more The manuscript of Edessa or ms. 3290, a XVIII century Armenian manuscript kept at Biblioteca Universitaria di Bologna, has been thoroughly studied from the religious, artistic, historical and diagnostic point of view. Non-invasive measurements on the miniatures have been carried out in situ with portable instruments in order to evaluate the pictorial materials used to decorate this beautiful codex, lavishly illuminated with fullpage miniatures. The results of the diagnostic study suggested that at least three different painters, each one with its own characteristic palette, contributed to the illumination of the manuscript. Precious colorants were employed for painting, among which of particular interest is the combined use of ultramarine blue and gold, considered the most valuable pictorial materials available to painters. Such a study could be a starting point for a larger research on the heritage of Armenian manuscripts held in Italian institutions.

White zinc in linseed oil paintings: chemical, mechanical and aesthetic aspects

The interest of this research derived from the request for a scientific investigation of the obse... more The interest of this research derived from the request for a scientific investigation of the observed phenomenon from by few contemporary artists who, in some occasions, observed the formation of crequalure in rethinking areas where a paint layer of different colour was over imposed to a zinc white layer, on commercial canvases. To investigate this phenomenon several investigations to characterized chemical and physical proprieties of commercial white zinc pigments are carried out: XRD, ICP/OES, SEM/EDS, FTIR, GC-MS. Moreover, to several tests were performed in order to evidence the different behavior of the various white pigments referring to the miscibility and to the drying times. The paper shows how the size of the pigment particles affects the formation and the type of the craquelure.

On the fly synthesis of edit suggestions

Proceedings of the ACM on Programming Languages, 2019

When working with a document, users often perform context-specific repetitive edits – changes to ... more When working with a document, users often perform context-specific repetitive edits – changes to the document that are similar but specific to the contexts at their locations. Programming by demonstration/examples (PBD/PBE) systems automate these tasks by learning programs to perform the repetitive edits from demonstration or examples. However, PBD/PBE systems are not widely adopted, mainly because they require modal UIs – users must enter a special mode to give the demonstration/examples. This paper presents Blue-Pencil, a modeless system for synthesizing edit suggestions on the fly. Blue-Pencil observes users as they make changes to the document, silently identifies repetitive changes, and automatically suggests transformations that can apply at other locations. Blue-Pencil is parameterized – it allows the ”plug-and-play” of different PBE engines to support different document types and different kinds of transformations. We demonstrate this parameterization by instantiating Blue-P...

The valence electronic structure and conformational flexibility of epichlorohydrin

Physical Chemistry Chemical Physics, 2011

Carbon Allotropy and Carbon Dust in the Circumstellar and Interstellar Space

Radiopolymerization of beta(-)pinene: A case of chiral amplification

Radiat Phys Chem, 2006

Carbon Allotropy and Carbon Dust in the Circumstellar and Interstellar Space

Gamma-radiolysis and ozonolysis of polycyclic aromatic hydrocarbons (PAHs) in solution

Journal of Radioanalytical and Nuclear Chemistry, 2006

Summary The degradation of a mixture of 18 different polycyclic aromatic hydrocarbons (PAHs) has... more Summary The degradation of a mixture of 18 different polycyclic aromatic hydrocarbons (PAHs) has been studied in acetonitrile solution by usingg-radiation at radiation doses of 100, 200 and 300 kGy. The mixture of radiolyzed PAHs was analyzed by liquid chromatography (HPLC) using a diode array detector. Radiolysis at 100 kGy total dose is already sufficient to cause the complete disappearance of all PAHs with the exception of fluorene and crysene which still survive in small amounts. They are known to be among the most radiation-resistant PAHs and can be completely eliminated from the radiolyzed solution by a treatment with ozone. Alternatively higher radiation dose (200 kGy) is needed to eliminate fluorene and crysene completely from the acetonitrile solution. PAHs can be degraded completely with an excess of ozone but the distribution of products is of course different from that obtained by radiolysis and radiolysis followed by ozonolysis.

Application of analytical pyrolysis for the characterisation of old inks

Journal of Analytical and Applied Pyrolysis, 2007

In the last years particular attention has been dedicated to the analysis of iron-gall inks for t... more In the last years particular attention has been dedicated to the analysis of iron-gall inks for their effects on the degradation of paper. Mainly spectroscopic techniques devoted to the determination of iron have been studied, while a minor attention has been dedicated to the organic components.In this study we propose THM pyrolysis as a rapid tool for the characterisation of

Sorption Behaviour of Armenian Natural Zeolites

Fusion Science and Technology

The sorptive behavior of tritiated water on natural, irradiated, chemically treated and heated at... more The sorptive behavior of tritiated water on natural, irradiated, chemically treated and heated at high temperatures Armenian zeolites was studied and their capacity for the separation and enrichment of tritiated water was evaluated. The distribution coefficients from the batch experiments were calculated for different zeolites and vary between 0.23 and 3.01. The influence of temperature, acidity, basicity, specific activity, electron and gamma-irradiation on sorption has been studied.

Sorption behavior of tritiated water on Armenian natural zeolites

… of radioanalytical and …, 2005

... Y. Keheyan,1* S. Khachatryan,1 G. Christidis,2 D. Moraetis,2 R. Gevorkyan,3 H. Sarkisyan,3 H.... more

Py/GC/MS Analyses of Historical Papers

BioResources, 2008

The thermal degradation of cellulose is an important process in several fields such as the paper ... more The thermal degradation of cellulose is an important process in several fields such as the paper industry, biomass combustion, fire retardation, etc. Paper consists mostly of cellulose fibres. Although the fibre source has changed continiously from cotton or linen rags to wood, its nature is still vegetal. Pyrolysis in combination with gas chromatography and mass spectrometry has been used to identify the structures of thermal degradation products with the aim to characterize papers used in different centuries. Pyrolysis of cellulose has also been studied in the presence of the methylating reagent tetramethylammonium hydroxide (TMAH).

ChArACterIsAtIon of ColourAnts on A 15th Century ArmenIAn mAnusCrIpt by meAns of dIfferent speCtrosCopIC teChnIques e-PRESERVATIONscience

This contribution illustrates the results from the technical study of a 15 th century Armenian il... more This contribution illustrates the results from the technical study of a 15 th century Armenian illuminated manuscript produced at Aghtamar Island (Vaspurakan region, historic Armenia), presently kept in the collection of Matenadaran ancient manuscript museum, in Yerevan. Fifteen fragments taken from different miniatures in the manuscript were analysed by means of UV-Visible diffuse reflectance spectrophotometry with optic fibres (FORS), fluorimetry, Raman spectroscopy, SERS and SEM-EDX. The combination of molecular and elemental techniques allowed the characterisation and identification of colourants used in miniatures; these were carbon, cinnabar, indigo, iron-gall ink, orpiment, red lead, ultramarine blue, vergaut and white lead. A pink dye was assigned to lac dye according to preliminary measurements. The goal was to compare the results with a previously analysed 14 th century manuscript coming from the same region: were the same colourants used or not? 1 Introduction Illuminated...

γ-Radiation Induced Polymerization of a Chiral Monomer: A New Way to Produce Chiral Amplification

Origins of Life and Evolution of Biospheres, 2007

The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) ca... more The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT-IR spectroscopy also in comparison to a reference β(−)pinene resin prepared by cationic polymerization. A highly ordered structure was found in the case of the radiopolymer in comparison to the resin from cationic polymerization. Polarimetric measurements have shown astonishing enhancement in the optical activity of the radiopolymer and radiodimer in comparison to the starting optical activity of the β(−) pinene monomer. Also DSC (differential scanning calorimetry) data supports the unexpected highly ordered structure for the β(−)pinene radiopolymer in comparison to the resin prepared by cationic polymerization. The results have been discussed in terms of amplification of chirality caused by + radiation and the implications of this fact on the mechanism of chiral amplification on prebiotic molecules. Keywords β(−)pinene. terpene resin. radiopolymerization. optical activity. chirality. chiral amplification. origin of chirality. origin of life

A study of some illuminated Armenian manuscripts

SEM‐EDS analysis of ancient bronze artifacts of urartian period from Yegheghnadzor region, Armenia

Journal of Microscopy

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwes... more The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia, Yegheghnadzor archaeological site, are discussed. The samples are dated to the 7-6 BCE from the Urartian period. The artifacts were corroded and a multilayer structure was formed. To study the stratigraphy of layers and their composition the samples have been analyzed using SEM-EDS (Scanning Electron Microscopy, Energy Dispersive Spectrometry) and OM (Optical Microscopy) techniques. The bronze finds appear with the typical incrustations rich in alloy alteration compounds. Concentrations of copper and tin in the alloys were quantified by SEM-EDS: the pattern and the percentage of the alloy are the same for the belts. Regarding the bowl sample, it is constituted by two foils, perfectly in contact but different in colour, thickness and composition. The results evidenced that only two elements participate in forming alloy composition in the samples: Cu and Sn. The tin content is variable from 7.75 to 13.56%. Other elements such as Ag, As, Fe, Ni, P, Pb, Sb, and Zn are lower more than 1% and can be considered as impurities. This article is protected by copyright. All rights reserved.

gamma-Radiation Induced Polymerization of a Chiral Monomer: A New Way to Produce Chiral Amplification

Origins Life Evol Biosphere, 2006

The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) ca... more The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT-IR spectroscopy also in comparison to a reference β(−)pinene resin prepared by cationic polymerization. A highly ordered structure was found in the case of the radiopolymer in comparison to the resin from cationic polymerization. Polarimetric measurements have shown astonishing enhancement in the optical activity of the radiopolymer and radiodimer in comparison to the starting optical activity of the β(−) pinene monomer. Also DSC (differential scanning calorimetry) data supports the unexpected highly ordered structure for the β(−)pinene radiopolymer in comparison to the resin prepared by cationic polymerization. The results have been discussed in terms of amplification of chirality caused by + radiation and the implications of this fact on the mechanism of chiral amplification on prebiotic molecules. Keywords β(−)pinene. terpene resin. radiopolymerization. optical activity. chirality. chiral amplification. origin of chirality. origin of life

?-Radiation Induced Polymerization of a Chiral Monomer: A New Way to Produce Chiral Amplification

Origins Life Evol Biosphere, 2006

The treatment of the terpene β(−)pinene with γ radiation (at dose level: 150, 300 and 600 kGy) ca... more The treatment of the terpene β(−)pinene with γ radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT–IR spectroscopy also in comparison to a reference β(−)pinene resin prepared by cationic polymerization. A highly ordered structure was found in the case of the radiopolymer in comparison to the resin from cationic polymerization. Polarimetric measurements have shown astonishing enhancement in the optical activity of the radiopolymer and radiodimer in comparison to the starting optical activity of the β(−)pinene monomer. Also DSC (differential scanning calorimetry) data supports the unexpected highly ordered structure for the β(−)pinene radiopolymer in comparison to the resin prepared by cationic polymerization. The results have been discussed in terms of amplification of chirality caused by γ radiation and the implications of this fact on the mechanism of chiral amplification on prebiotic molecules.

Pyrolysis of simple chiral aromatic alcohols. Survivability and preservation of chirality on minerals of astrophysical interest: a case study

Proceedings of the International Astronomical Union, 2011

The aim of the present work is to analyze the influence of temperature and minerals such ilmenite... more The aim of the present work is to analyze the influence of temperature and minerals such ilmenite, Mg 2 Si, SiO 2 :MgO:Fe 2 O 3 , etc. on the decomposition and the racemization of the most simple chiral aromatic molecule, i.e. (R+)-and (S-)-1phenylethanol (Pe-OH). To investigate this phenomena the minerals are deposited on the quartz liner of the pyrolizer, coupled with gas chromatograph equipped with a chiral column to discriminate enantiomers and diastereoisomers. A quadrupole mass spectrometer acts as the gas chromatograph detector. Various pyrolytic experiments, at temperatures from 100 to 700°C with and without minerals as catalysts, were performed. It results that the effect of the catalyst on the decomposition and on the extent of the racemization depends on its nature. However, the crystalline silicates appears to be more active than others. As regards chemical survivability we have found that, in the presence of minerals, at temperatures up to 200°C the 1-Pe-OH enantiomers start to decompose with formation of styrene, acetophenone, and optically active benzylic ethers. The yield of the reaction of chiral benzylic ethers is temperature dependent and reaches to maximal value at 500°C. The stereochemistry of the reaction has also been investigated. .

A New Painting Fragment from Erebuni and an Overview of Urartian Wall Paintings

Over the Mountains and Far Away: Studies in Near Eastern history and archaeology presented to Mirjo Salvini on the occasion of his 80th birthday, 2019

Spectroscopic Study of an Armenian Manuscript from Biblioteca Universitaria

The manuscript of Edessa or ms. 3290, a XVIII century Armenian manuscript kept at Biblioteca Univ... more The manuscript of Edessa or ms. 3290, a XVIII century Armenian manuscript kept at Biblioteca Universitaria di Bologna, has been thoroughly studied from the religious, artistic, historical and diagnostic point of view. Non-invasive measurements on the miniatures have been carried out in situ with portable instruments in order to evaluate the pictorial materials used to decorate this beautiful codex, lavishly illuminated with fullpage miniatures. The results of the diagnostic study suggested that at least three different painters, each one with its own characteristic palette, contributed to the illumination of the manuscript. Precious colorants were employed for painting, among which of particular interest is the combined use of ultramarine blue and gold, considered the most valuable pictorial materials available to painters. Such a study could be a starting point for a larger research on the heritage of Armenian manuscripts held in Italian institutions.

White zinc in linseed oil paintings: chemical, mechanical and aesthetic aspects

The interest of this research derived from the request for a scientific investigation of the obse... more The interest of this research derived from the request for a scientific investigation of the observed phenomenon from by few contemporary artists who, in some occasions, observed the formation of crequalure in rethinking areas where a paint layer of different colour was over imposed to a zinc white layer, on commercial canvases. To investigate this phenomenon several investigations to characterized chemical and physical proprieties of commercial white zinc pigments are carried out: XRD, ICP/OES, SEM/EDS, FTIR, GC-MS. Moreover, to several tests were performed in order to evidence the different behavior of the various white pigments referring to the miscibility and to the drying times. The paper shows how the size of the pigment particles affects the formation and the type of the craquelure.

On the fly synthesis of edit suggestions

Proceedings of the ACM on Programming Languages, 2019

When working with a document, users often perform context-specific repetitive edits – changes to ... more When working with a document, users often perform context-specific repetitive edits – changes to the document that are similar but specific to the contexts at their locations. Programming by demonstration/examples (PBD/PBE) systems automate these tasks by learning programs to perform the repetitive edits from demonstration or examples. However, PBD/PBE systems are not widely adopted, mainly because they require modal UIs – users must enter a special mode to give the demonstration/examples. This paper presents Blue-Pencil, a modeless system for synthesizing edit suggestions on the fly. Blue-Pencil observes users as they make changes to the document, silently identifies repetitive changes, and automatically suggests transformations that can apply at other locations. Blue-Pencil is parameterized – it allows the ”plug-and-play” of different PBE engines to support different document types and different kinds of transformations. We demonstrate this parameterization by instantiating Blue-P...

The valence electronic structure and conformational flexibility of epichlorohydrin

Physical Chemistry Chemical Physics, 2011

Carbon Allotropy and Carbon Dust in the Circumstellar and Interstellar Space

Radiopolymerization of beta(-)pinene: A case of chiral amplification

Radiat Phys Chem, 2006

Carbon Allotropy and Carbon Dust in the Circumstellar and Interstellar Space

Gamma-radiolysis and ozonolysis of polycyclic aromatic hydrocarbons (PAHs) in solution

Journal of Radioanalytical and Nuclear Chemistry, 2006

Summary The degradation of a mixture of 18 different polycyclic aromatic hydrocarbons (PAHs) has... more Summary The degradation of a mixture of 18 different polycyclic aromatic hydrocarbons (PAHs) has been studied in acetonitrile solution by usingg-radiation at radiation doses of 100, 200 and 300 kGy. The mixture of radiolyzed PAHs was analyzed by liquid chromatography (HPLC) using a diode array detector. Radiolysis at 100 kGy total dose is already sufficient to cause the complete disappearance of all PAHs with the exception of fluorene and crysene which still survive in small amounts. They are known to be among the most radiation-resistant PAHs and can be completely eliminated from the radiolyzed solution by a treatment with ozone. Alternatively higher radiation dose (200 kGy) is needed to eliminate fluorene and crysene completely from the acetonitrile solution. PAHs can be degraded completely with an excess of ozone but the distribution of products is of course different from that obtained by radiolysis and radiolysis followed by ozonolysis.

Application of analytical pyrolysis for the characterisation of old inks

Journal of Analytical and Applied Pyrolysis, 2007

In the last years particular attention has been dedicated to the analysis of iron-gall inks for t... more In the last years particular attention has been dedicated to the analysis of iron-gall inks for their effects on the degradation of paper. Mainly spectroscopic techniques devoted to the determination of iron have been studied, while a minor attention has been dedicated to the organic components.In this study we propose THM pyrolysis as a rapid tool for the characterisation of

Sorption Behaviour of Armenian Natural Zeolites

Fusion Science and Technology

The sorptive behavior of tritiated water on natural, irradiated, chemically treated and heated at... more The sorptive behavior of tritiated water on natural, irradiated, chemically treated and heated at high temperatures Armenian zeolites was studied and their capacity for the separation and enrichment of tritiated water was evaluated. The distribution coefficients from the batch experiments were calculated for different zeolites and vary between 0.23 and 3.01. The influence of temperature, acidity, basicity, specific activity, electron and gamma-irradiation on sorption has been studied.

Sorption behavior of tritiated water on Armenian natural zeolites

… of radioanalytical and …, 2005

... Y. Keheyan,1* S. Khachatryan,1 G. Christidis,2 D. Moraetis,2 R. Gevorkyan,3 H. Sarkisyan,3 H.... more

Py/GC/MS Analyses of Historical Papers

BioResources, 2008

The thermal degradation of cellulose is an important process in several fields such as the paper ... more The thermal degradation of cellulose is an important process in several fields such as the paper industry, biomass combustion, fire retardation, etc. Paper consists mostly of cellulose fibres. Although the fibre source has changed continiously from cotton or linen rags to wood, its nature is still vegetal. Pyrolysis in combination with gas chromatography and mass spectrometry has been used to identify the structures of thermal degradation products with the aim to characterize papers used in different centuries. Pyrolysis of cellulose has also been studied in the presence of the methylating reagent tetramethylammonium hydroxide (TMAH).

ChArACterIsAtIon of ColourAnts on A 15th Century ArmenIAn mAnusCrIpt by meAns of dIfferent speCtrosCopIC teChnIques e-PRESERVATIONscience

This contribution illustrates the results from the technical study of a 15 th century Armenian il... more This contribution illustrates the results from the technical study of a 15 th century Armenian illuminated manuscript produced at Aghtamar Island (Vaspurakan region, historic Armenia), presently kept in the collection of Matenadaran ancient manuscript museum, in Yerevan. Fifteen fragments taken from different miniatures in the manuscript were analysed by means of UV-Visible diffuse reflectance spectrophotometry with optic fibres (FORS), fluorimetry, Raman spectroscopy, SERS and SEM-EDX. The combination of molecular and elemental techniques allowed the characterisation and identification of colourants used in miniatures; these were carbon, cinnabar, indigo, iron-gall ink, orpiment, red lead, ultramarine blue, vergaut and white lead. A pink dye was assigned to lac dye according to preliminary measurements. The goal was to compare the results with a previously analysed 14 th century manuscript coming from the same region: were the same colourants used or not? 1 Introduction Illuminated...

γ-Radiation Induced Polymerization of a Chiral Monomer: A New Way to Produce Chiral Amplification

Origins of Life and Evolution of Biospheres, 2007

The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) ca... more The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT-IR spectroscopy also in comparison to a reference β(−)pinene resin prepared by cationic polymerization. A highly ordered structure was found in the case of the radiopolymer in comparison to the resin from cationic polymerization. Polarimetric measurements have shown astonishing enhancement in the optical activity of the radiopolymer and radiodimer in comparison to the starting optical activity of the β(−) pinene monomer. Also DSC (differential scanning calorimetry) data supports the unexpected highly ordered structure for the β(−)pinene radiopolymer in comparison to the resin prepared by cationic polymerization. The results have been discussed in terms of amplification of chirality caused by + radiation and the implications of this fact on the mechanism of chiral amplification on prebiotic molecules. Keywords β(−)pinene. terpene resin. radiopolymerization. optical activity. chirality. chiral amplification. origin of chirality. origin of life

A study of some illuminated Armenian manuscripts

SEM‐EDS analysis of ancient bronze artifacts of urartian period from Yegheghnadzor region, Armenia

Journal of Microscopy

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwes... more The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia, Yegheghnadzor archaeological site, are discussed. The samples are dated to the 7-6 BCE from the Urartian period. The artifacts were corroded and a multilayer structure was formed. To study the stratigraphy of layers and their composition the samples have been analyzed using SEM-EDS (Scanning Electron Microscopy, Energy Dispersive Spectrometry) and OM (Optical Microscopy) techniques. The bronze finds appear with the typical incrustations rich in alloy alteration compounds. Concentrations of copper and tin in the alloys were quantified by SEM-EDS: the pattern and the percentage of the alloy are the same for the belts. Regarding the bowl sample, it is constituted by two foils, perfectly in contact but different in colour, thickness and composition. The results evidenced that only two elements participate in forming alloy composition in the samples: Cu and Sn. The tin content is variable from 7.75 to 13.56%. Other elements such as Ag, As, Fe, Ni, P, Pb, Sb, and Zn are lower more than 1% and can be considered as impurities. This article is protected by copyright. All rights reserved.

gamma-Radiation Induced Polymerization of a Chiral Monomer: A New Way to Produce Chiral Amplification

Origins Life Evol Biosphere, 2006

The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) ca... more The treatment of the terpene β(−)pinene with + radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT-IR spectroscopy also in comparison to a reference β(−)pinene resin prepared by cationic polymerization. A highly ordered structure was found in the case of the radiopolymer in comparison to the resin from cationic polymerization. Polarimetric measurements have shown astonishing enhancement in the optical activity of the radiopolymer and radiodimer in comparison to the starting optical activity of the β(−) pinene monomer. Also DSC (differential scanning calorimetry) data supports the unexpected highly ordered structure for the β(−)pinene radiopolymer in comparison to the resin prepared by cationic polymerization. The results have been discussed in terms of amplification of chirality caused by + radiation and the implications of this fact on the mechanism of chiral amplification on prebiotic molecules. Keywords β(−)pinene. terpene resin. radiopolymerization. optical activity. chirality. chiral amplification. origin of chirality. origin of life

?-Radiation Induced Polymerization of a Chiral Monomer: A New Way to Produce Chiral Amplification

Origins Life Evol Biosphere, 2006

The treatment of the terpene β(−)pinene with γ radiation (at dose level: 150, 300 and 600 kGy) ca... more The treatment of the terpene β(−)pinene with γ radiation (at dose level: 150, 300 and 600 kGy) causes its polymerization into a resin and into a dimer. The yield of the resin and of the dimer appears to be linearly dependent to the radiation dose. The structure of the products was studied by FT–IR spectroscopy also in comparison to a reference β(−)pinene resin prepared by cationic polymerization. A highly ordered structure was found in the case of the radiopolymer in comparison to the resin from cationic polymerization. Polarimetric measurements have shown astonishing enhancement in the optical activity of the radiopolymer and radiodimer in comparison to the starting optical activity of the β(−)pinene monomer. Also DSC (differential scanning calorimetry) data supports the unexpected highly ordered structure for the β(−)pinene radiopolymer in comparison to the resin prepared by cationic polymerization. The results have been discussed in terms of amplification of chirality caused by γ radiation and the implications of this fact on the mechanism of chiral amplification on prebiotic molecules.

Pyrolysis of simple chiral aromatic alcohols. Survivability and preservation of chirality on minerals of astrophysical interest: a case study

Proceedings of the International Astronomical Union, 2011

The aim of the present work is to analyze the influence of temperature and minerals such ilmenite... more The aim of the present work is to analyze the influence of temperature and minerals such ilmenite, Mg 2 Si, SiO 2 :MgO:Fe 2 O 3 , etc. on the decomposition and the racemization of the most simple chiral aromatic molecule, i.e. (R+)-and (S-)-1phenylethanol (Pe-OH). To investigate this phenomena the minerals are deposited on the quartz liner of the pyrolizer, coupled with gas chromatograph equipped with a chiral column to discriminate enantiomers and diastereoisomers. A quadrupole mass spectrometer acts as the gas chromatograph detector. Various pyrolytic experiments, at temperatures from 100 to 700°C with and without minerals as catalysts, were performed. It results that the effect of the catalyst on the decomposition and on the extent of the racemization depends on its nature. However, the crystalline silicates appears to be more active than others. As regards chemical survivability we have found that, in the presence of minerals, at temperatures up to 200°C the 1-Pe-OH enantiomers start to decompose with formation of styrene, acetophenone, and optically active benzylic ethers. The yield of the reaction of chiral benzylic ethers is temperature dependent and reaches to maximal value at 500°C. The stereochemistry of the reaction has also been investigated. .