Please cite this article in press as: P. Baraldi, et al., Pigment characterization of drawings an... more Please cite this article in press as: P. Baraldi, et al., Pigment characterization of drawings and painted layers under 5th–7th centuries wall mosaics from Ravenna (Italy), Journal of Cultural Heritage (2016), http://dx. a b s t r a c t The results of a multi-analytical investigation on preparatory drawings below three late antique wall mosaics in Ravenna (Italy) are reported and discussed. Examinations were made on two sinopiae in mosaic substrates detached from the apse of the basilica of St. Apollinare in Classe and on the undercol-oring characterizing some finds of wall mosaics coming from the basilicas of St. Agata Maggiore and St. Croce. Due to the historic and archaeological relevance of the finds, the research was carried out mainly through noninvasive techniques, such as fiber optics reflectance spectroscopy (FORS) and energy dis-persive X-ray fluorescence spectrometry (EDXRF). Analyses by Fourier transform infrared spectroscopy (FTIR) and Raman micro-spectroscopy (Raman) were only performed on incoherent material and small loss particles in the interstices among the tesserae. In some selected painted area, visible-induced infrared luminescence (VIL) was employed to verify if Egyptian blue was used and how was distributed, if present. By comparing the results obtained with the different techniques, a proposal about the nature of the pigments was formulated: the pigments employed to make the sinopiae from St. Apollinare in Classe are iron-based pigments, while the analyses of the undercoloring show a more complex character, where the use of a broader palette of pigments was recognized (red ochre, green earth, Egyptian blue).
This paper explores the added value of micro-chemical and microscopic approaches to gather scient... more This paper explores the added value of micro-chemical and microscopic approaches to gather scientific evidence that can technically explain the pictorial quality of an egg-tempera painting, and underpin assessments that otherwise would be based on naked eye observations only. Demonstration is here provided via the interdisciplinary investigation of the original technique used by Giovanni del Biondo in the polyptych Annunciation and Saints (1385 ca), Galleria dell'Accademia, Florence, Italy. The exquisite surface appearance makes this panel painting remarkable compared to artworks by coeval artists. Imaging techniques (UV, IR and IR false color), non-invasive single spot techniques (XRF and FORS spectrometry) and analytical investigations on eight selected micro-samples (ATR-FTIR, GC/MS and Py/GC–MS, ESEM-EDS) were combined to retrieve the palette and identify organic binding media and a superficial coating layer. Stratigraphic and micro-chemical data confirmed the use of a relatively simple egg-tempera technique applied on a ground made of gypsum mixed with animal glue, without complex stratigraphic superimposition of preparation and pictorial layers. Various pigments were identified, among which is the precious lapis lazuli. While Py/GC–MS highlight that the coating is made of dammar resin and honey mixed with animal glue, the results allow us to state that the painting was not intentionally varnished by Giovanni del Biondo. These outcomes shed a new light on the technical knowledge of this polyptych, and prove how challenging is the attempt to categorize egg-tempera recipes used by ancient painters at the turn of the 14th century.
This article covers a methodology for evaluating the effectiveness of cleaning two
Russian icons.... more This article covers a methodology for evaluating the effectiveness of cleaning two Russian icons. The icons belong to a group of five from the same iconographic school, dating from the 16th to 17th centuries. An integrated and complementary approach to varnish and overpaint removal involved microscopic techniques (optical and scanning electron microscopy) and colorimetry (CIE L*a*b* system). The materials and techniques used in these icons have been characterized previously. Cleaning revealed extensive overpainting that had not only dramatically changed the original appearance, but also the meaning and attribution of one of the two icons. The analyses carried out were useful in determining the extent of the overpainting and led to a better assessment of the results and effectiveness of the restoration.
This article presents an integrated approach for the authentication of five Russian icons through... more This article presents an integrated approach for the authentication of five Russian icons through the study of their paint materials (elemental composition and stratigraphic mapping), state of conservation and artistic technique. The results of the applied analytical protocol, involving optical and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry and Fourier transformed infrared spectroscopy/microspectroscopy, led to the conclusion that the five icons belong to the same group and iconographic school (from Northern Russia) and date from the end of the 16th century to the beginning of 17th century. Because of massive overpainting, the icons ‘‘suffered’’ a change in iconographic style and significance, and restoration treatment brought to light the original painting and its attribution. Identification of the composition of the original chromatic palette used by the iconographer, the stratigraphic mapping and the conservation state of the painting materials, along with the features of the original artistic technique, furnished key elements for the icons’ authentication. Here, we present the first experimental data concerning the identification of the authentication characteristics, being part of a large project that has as its final aim the evaluation of the effectiveness and effects of the cleaning agent on the paint layers.
A recent restoration of the mosaics of the Baptistery in Florence enabled the collection and anal... more A recent restoration of the mosaics of the Baptistery in Florence enabled the collection and analysis of a group of glass tesserae. Twenty-three tesserae, dated between the end of the 13th century and the first half of the 14th century, showing different colors were sampled and analyzed to identify the raw materials, colorants and opacifiers employed in their production.
An optical fiber sensor for gastric pH detection is described, making use of plastic fibers as li... more An optical fiber sensor for gastric pH detection is described, making use of plastic fibers as light carriers and a proper electronic system for both source driving and signal processing. The use of a suitable microprocessor and an internal buffer allows the realization of a portable and reliable device, fed by batteries. The indicators, bromophenol blue (BPB) or thymol blue (TB), are immobilized on controlled pore glass (CPG) fixed at the end of plastic optical fibers following a proprietary process. The realized optrode, satisfying clinical requirements, was tested `in vitro.' A precision of <EQ 0.04 pH units and a response time of (<EQ 15 seconds) were reached.
In the present paper optical fiber sensors for monitoring and detection of foregut functional dis... more In the present paper optical fiber sensors for monitoring and detection of foregut functional diseases are described. Bile-containing refluxes and pH are the parameters already investigated with optical fibers and both in vitro and in vivo performances of these sensors are described.
The present work is concerned with the development of an optical-fibre sensor for monitoring pH i... more The present work is concerned with the development of an optical-fibre sensor for monitoring pH in the foregut in the extended range 1.0 8.0. Controlled pore glasses (CPGs), with covalently bound chromophore, are fixed at the end of plastic optical fibres using a proprietary process. A good sensitivity, fast response time, the small dimensions of the probe and the bioconipatibility of the materials utilized make the sensor suitable for in vivo measurements.
The detection of chemical parameters by means of optical fibres has had a decisive boost in recen... more The detection of chemical parameters by means of optical fibres has had a decisive boost in recent years; the realization of these devices is related to the development of a great number of techniques. The former are characterized by a reagent fixed to an optical fibre, a procedure which is not in itself unique. The silylation technique is one of the most widkly used for optrode realization. It generally involves an organosilicon compound that reacts with an external support or directly on the surface of the fibres with one or more functional groups and gives the supports a new functionality. Obviously the activation of the surface must be followed by other appropriate reactions so as to be able to immobilize the optically sensitive reagent. Silylation can be performed either on external glass or quartz supports or directly on the fibre itself. From a chemical point of view, there is not a big difference on where the chemical reaction takes place, but the same cannot be stated from the optical point of view. By changing where the silylation is performed, it is possible to change the optical path and consequently the signal-to-noise ratio, which is strictly related to the performance of the sensor. In fact, if the optical-fibre sensor is to be launched on the market, it must be competitive, in terns of cost and performance, when compared with other instruments that measure the same chemical species. Some of the most significant silylated optrodes are reported here, together with the associated optoelectronic instrumentation. Moreover, the advantages and drawbacks of the different procedures are taken into account.
An optical fiber sensor for gastric pH detection is here described, making use of plastic optical... more An optical fiber sensor for gastric pH detection is here described, making use of plastic optical fibers (POF) as light carriers and a proper electronic system for both source driving and signal processing. The use of a suitable microprocessor and an internal buffer allows the realization of a portable and reliable device, fed by batteries. The indicators, bromophenol blue (BPB) or thymol blue (TB), ar immobilized on controlled pore glasses (CPGs) fixed at the end of POFs following a propriety process. The optrode, satisfying clinical requirements, was tested in vitro and in vivo. Precision +/- 0.05 pH units and response time (+/- 25 seconds) were reached.
This paper describes an extensive spectrophotometric study on several acid-base indicators immobi... more This paper describes an extensive spectrophotometric study on several acid-base indicators immobilized on controlled pore glass by means of a silylation process. The spectrophotometric properties of the immobilized indicators are at variance with those of the free indicators as far as pH dependence and ranges are concerned. The differing of the spectrophotometric properties of the indicators, when the latter are immobilized on solid supports, can be justified from the point of view of steric hindrance and of the reactivity of the indicators. Particular attention was paid to the pH-sensitive bands and their position. The effect of ionic strength is also investigated. Early tests performed with optical fibers are described.
The present work is concerned with the development of an optical-fiber pH sensor for gastric moni... more The present work is concerned with the development of an optical-fiber pH sensor for gastric monitoring. Bromophenol blue is used as a chromophore, which is immobilized on controlled-pore glasses (CPGs) by means of a silylation process. As far as the optoelectronic unit is concerned, light-emitting diodes as sources and an appropriate electronic circuit as detection system are utilized. Treated CPGs are fixed at the end of two plastic optical fibers (core diameter = 500 ~m) by means of a proprietary process; a reflector made of Teflon ®, anchored to the distal end of the fibers, ensures good fibers/probe coupling efficiency. The behavior of the realized probe is carefully investigated, with particular attention devoted to the presence of hysteresis, to ionic strength and temperature effect, and to its lifetime. The fast response time, thanks to the absence of a mechanical envelope, the small dimensions of the probe, and the biocompatihility of the utilized materials make this sensor suitable for in vivo measurements.
Journal of The Chemical Society, Chemical Communications, 1987
The nitroester (I) was shown to give rise to 1,3-dipolar cycloadditions with diazomethane and 2-d... more The nitroester (I) was shown to give rise to 1,3-dipolar cycloadditions with diazomethane and 2-diazopropane, affording the bicyclic derivatives (4) and (5) via the unstable primary cycloadducts (2) and (31, respectively.
Please cite this article in press as: P. Baraldi, et al., Pigment characterization of drawings an... more Please cite this article in press as: P. Baraldi, et al., Pigment characterization of drawings and painted layers under 5th–7th centuries wall mosaics from Ravenna (Italy), Journal of Cultural Heritage (2016), http://dx. a b s t r a c t The results of a multi-analytical investigation on preparatory drawings below three late antique wall mosaics in Ravenna (Italy) are reported and discussed. Examinations were made on two sinopiae in mosaic substrates detached from the apse of the basilica of St. Apollinare in Classe and on the undercol-oring characterizing some finds of wall mosaics coming from the basilicas of St. Agata Maggiore and St. Croce. Due to the historic and archaeological relevance of the finds, the research was carried out mainly through noninvasive techniques, such as fiber optics reflectance spectroscopy (FORS) and energy dis-persive X-ray fluorescence spectrometry (EDXRF). Analyses by Fourier transform infrared spectroscopy (FTIR) and Raman micro-spectroscopy (Raman) were only performed on incoherent material and small loss particles in the interstices among the tesserae. In some selected painted area, visible-induced infrared luminescence (VIL) was employed to verify if Egyptian blue was used and how was distributed, if present. By comparing the results obtained with the different techniques, a proposal about the nature of the pigments was formulated: the pigments employed to make the sinopiae from St. Apollinare in Classe are iron-based pigments, while the analyses of the undercoloring show a more complex character, where the use of a broader palette of pigments was recognized (red ochre, green earth, Egyptian blue).
This paper explores the added value of micro-chemical and microscopic approaches to gather scient... more This paper explores the added value of micro-chemical and microscopic approaches to gather scientific evidence that can technically explain the pictorial quality of an egg-tempera painting, and underpin assessments that otherwise would be based on naked eye observations only. Demonstration is here provided via the interdisciplinary investigation of the original technique used by Giovanni del Biondo in the polyptych Annunciation and Saints (1385 ca), Galleria dell'Accademia, Florence, Italy. The exquisite surface appearance makes this panel painting remarkable compared to artworks by coeval artists. Imaging techniques (UV, IR and IR false color), non-invasive single spot techniques (XRF and FORS spectrometry) and analytical investigations on eight selected micro-samples (ATR-FTIR, GC/MS and Py/GC–MS, ESEM-EDS) were combined to retrieve the palette and identify organic binding media and a superficial coating layer. Stratigraphic and micro-chemical data confirmed the use of a relatively simple egg-tempera technique applied on a ground made of gypsum mixed with animal glue, without complex stratigraphic superimposition of preparation and pictorial layers. Various pigments were identified, among which is the precious lapis lazuli. While Py/GC–MS highlight that the coating is made of dammar resin and honey mixed with animal glue, the results allow us to state that the painting was not intentionally varnished by Giovanni del Biondo. These outcomes shed a new light on the technical knowledge of this polyptych, and prove how challenging is the attempt to categorize egg-tempera recipes used by ancient painters at the turn of the 14th century.
This article covers a methodology for evaluating the effectiveness of cleaning two
Russian icons.... more This article covers a methodology for evaluating the effectiveness of cleaning two Russian icons. The icons belong to a group of five from the same iconographic school, dating from the 16th to 17th centuries. An integrated and complementary approach to varnish and overpaint removal involved microscopic techniques (optical and scanning electron microscopy) and colorimetry (CIE L*a*b* system). The materials and techniques used in these icons have been characterized previously. Cleaning revealed extensive overpainting that had not only dramatically changed the original appearance, but also the meaning and attribution of one of the two icons. The analyses carried out were useful in determining the extent of the overpainting and led to a better assessment of the results and effectiveness of the restoration.
This article presents an integrated approach for the authentication of five Russian icons through... more This article presents an integrated approach for the authentication of five Russian icons through the study of their paint materials (elemental composition and stratigraphic mapping), state of conservation and artistic technique. The results of the applied analytical protocol, involving optical and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry and Fourier transformed infrared spectroscopy/microspectroscopy, led to the conclusion that the five icons belong to the same group and iconographic school (from Northern Russia) and date from the end of the 16th century to the beginning of 17th century. Because of massive overpainting, the icons ‘‘suffered’’ a change in iconographic style and significance, and restoration treatment brought to light the original painting and its attribution. Identification of the composition of the original chromatic palette used by the iconographer, the stratigraphic mapping and the conservation state of the painting materials, along with the features of the original artistic technique, furnished key elements for the icons’ authentication. Here, we present the first experimental data concerning the identification of the authentication characteristics, being part of a large project that has as its final aim the evaluation of the effectiveness and effects of the cleaning agent on the paint layers.
A recent restoration of the mosaics of the Baptistery in Florence enabled the collection and anal... more A recent restoration of the mosaics of the Baptistery in Florence enabled the collection and analysis of a group of glass tesserae. Twenty-three tesserae, dated between the end of the 13th century and the first half of the 14th century, showing different colors were sampled and analyzed to identify the raw materials, colorants and opacifiers employed in their production.
An optical fiber sensor for gastric pH detection is described, making use of plastic fibers as li... more An optical fiber sensor for gastric pH detection is described, making use of plastic fibers as light carriers and a proper electronic system for both source driving and signal processing. The use of a suitable microprocessor and an internal buffer allows the realization of a portable and reliable device, fed by batteries. The indicators, bromophenol blue (BPB) or thymol blue (TB), are immobilized on controlled pore glass (CPG) fixed at the end of plastic optical fibers following a proprietary process. The realized optrode, satisfying clinical requirements, was tested `in vitro.' A precision of <EQ 0.04 pH units and a response time of (<EQ 15 seconds) were reached.
In the present paper optical fiber sensors for monitoring and detection of foregut functional dis... more In the present paper optical fiber sensors for monitoring and detection of foregut functional diseases are described. Bile-containing refluxes and pH are the parameters already investigated with optical fibers and both in vitro and in vivo performances of these sensors are described.
The present work is concerned with the development of an optical-fibre sensor for monitoring pH i... more The present work is concerned with the development of an optical-fibre sensor for monitoring pH in the foregut in the extended range 1.0 8.0. Controlled pore glasses (CPGs), with covalently bound chromophore, are fixed at the end of plastic optical fibres using a proprietary process. A good sensitivity, fast response time, the small dimensions of the probe and the bioconipatibility of the materials utilized make the sensor suitable for in vivo measurements.
The detection of chemical parameters by means of optical fibres has had a decisive boost in recen... more The detection of chemical parameters by means of optical fibres has had a decisive boost in recent years; the realization of these devices is related to the development of a great number of techniques. The former are characterized by a reagent fixed to an optical fibre, a procedure which is not in itself unique. The silylation technique is one of the most widkly used for optrode realization. It generally involves an organosilicon compound that reacts with an external support or directly on the surface of the fibres with one or more functional groups and gives the supports a new functionality. Obviously the activation of the surface must be followed by other appropriate reactions so as to be able to immobilize the optically sensitive reagent. Silylation can be performed either on external glass or quartz supports or directly on the fibre itself. From a chemical point of view, there is not a big difference on where the chemical reaction takes place, but the same cannot be stated from the optical point of view. By changing where the silylation is performed, it is possible to change the optical path and consequently the signal-to-noise ratio, which is strictly related to the performance of the sensor. In fact, if the optical-fibre sensor is to be launched on the market, it must be competitive, in terns of cost and performance, when compared with other instruments that measure the same chemical species. Some of the most significant silylated optrodes are reported here, together with the associated optoelectronic instrumentation. Moreover, the advantages and drawbacks of the different procedures are taken into account.
An optical fiber sensor for gastric pH detection is here described, making use of plastic optical... more An optical fiber sensor for gastric pH detection is here described, making use of plastic optical fibers (POF) as light carriers and a proper electronic system for both source driving and signal processing. The use of a suitable microprocessor and an internal buffer allows the realization of a portable and reliable device, fed by batteries. The indicators, bromophenol blue (BPB) or thymol blue (TB), ar immobilized on controlled pore glasses (CPGs) fixed at the end of POFs following a propriety process. The optrode, satisfying clinical requirements, was tested in vitro and in vivo. Precision +/- 0.05 pH units and response time (+/- 25 seconds) were reached.
This paper describes an extensive spectrophotometric study on several acid-base indicators immobi... more This paper describes an extensive spectrophotometric study on several acid-base indicators immobilized on controlled pore glass by means of a silylation process. The spectrophotometric properties of the immobilized indicators are at variance with those of the free indicators as far as pH dependence and ranges are concerned. The differing of the spectrophotometric properties of the indicators, when the latter are immobilized on solid supports, can be justified from the point of view of steric hindrance and of the reactivity of the indicators. Particular attention was paid to the pH-sensitive bands and their position. The effect of ionic strength is also investigated. Early tests performed with optical fibers are described.
The present work is concerned with the development of an optical-fiber pH sensor for gastric moni... more The present work is concerned with the development of an optical-fiber pH sensor for gastric monitoring. Bromophenol blue is used as a chromophore, which is immobilized on controlled-pore glasses (CPGs) by means of a silylation process. As far as the optoelectronic unit is concerned, light-emitting diodes as sources and an appropriate electronic circuit as detection system are utilized. Treated CPGs are fixed at the end of two plastic optical fibers (core diameter = 500 ~m) by means of a proprietary process; a reflector made of Teflon ®, anchored to the distal end of the fibers, ensures good fibers/probe coupling efficiency. The behavior of the realized probe is carefully investigated, with particular attention devoted to the presence of hysteresis, to ionic strength and temperature effect, and to its lifetime. The fast response time, thanks to the absence of a mechanical envelope, the small dimensions of the probe, and the biocompatihility of the utilized materials make this sensor suitable for in vivo measurements.
Journal of The Chemical Society, Chemical Communications, 1987
The nitroester (I) was shown to give rise to 1,3-dipolar cycloadditions with diazomethane and 2-d... more The nitroester (I) was shown to give rise to 1,3-dipolar cycloadditions with diazomethane and 2-diazopropane, affording the bicyclic derivatives (4) and (5) via the unstable primary cycloadducts (2) and (31, respectively.
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Papers by susanna bracci
Russian icons. The icons belong to a group of five from the same iconographic school, dating from
the 16th to 17th centuries. An integrated and complementary approach to varnish and overpaint
removal involved microscopic techniques (optical and scanning electron microscopy) and colorimetry
(CIE L*a*b* system). The materials and techniques used in these icons have been characterized
previously. Cleaning revealed extensive overpainting that had not only dramatically changed
the original appearance, but also the meaning and attribution of one of the two icons. The analyses
carried out were useful in determining the extent of the overpainting and led to a better assessment
of the results and effectiveness of the restoration.
layers.
Russian icons. The icons belong to a group of five from the same iconographic school, dating from
the 16th to 17th centuries. An integrated and complementary approach to varnish and overpaint
removal involved microscopic techniques (optical and scanning electron microscopy) and colorimetry
(CIE L*a*b* system). The materials and techniques used in these icons have been characterized
previously. Cleaning revealed extensive overpainting that had not only dramatically changed
the original appearance, but also the meaning and attribution of one of the two icons. The analyses
carried out were useful in determining the extent of the overpainting and led to a better assessment
of the results and effectiveness of the restoration.
layers.