Publications by authors named "Salvatore Siano"

7 Publications

  • Page 1 of 1

Terahertz Time-Domain Reconstruction of Coating Microstratigraphy on Gilded Surfaces.

Materials (Basel) 2019 Nov 21;12(23). Epub 2019 Nov 21.

Istituto di Fisica Applicata "Nello Carrara", Consiglio Nazionale delle Ricerche, v. M. del Piano 10, 50019 Sesto Fiorentino (FI), Italy.

Here, a systematic study in order to assess the potential of THz time domain reflectometry for measuring the thicknesses of overpaint layers applied on original gilded surfaces was carried out. The work is part of a thorough characterization campaign, which is going on at the Rijksmuseum for addressing the conservation problems of a set of 19th century gilded picture frames on which heavy coatings were applied in previous undocumented restoration interventions. To perform such non-invasive thickness measurements, an analytical protocol based on Gaussian fits of the THz pulse-echo temporal profiles was optimized through the preparation of suitable technical samples and the comparison with direct thickness measurements. Finally, the methodology was validated by characterizing the microstratigraphy of an original sculptural element from a gilded picture frame in the Rijksmuseum collection. The results achieved show the effectiveness of the present approach in revealing multi-layered dielectric microstructures with a spatial resolution of about 30 µm when using a spectral range up to 1.5 THz.
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http://dx.doi.org/10.3390/ma12233822DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6926600PMC
November 2019

High Energy Double Peak Pulse Laser Induced Plasma Spectroscopy for Metal Characterization Using a Passively Q-Switched Laser Source and CCD Detector.

Sensors (Basel) 2019 Aug 21;19(17). Epub 2019 Aug 21.

Istituto di Fisica Applicata "Nello Carrara"-CNR, 50019 Sesto Fiorentino, Italy.

Here, the development and testing of a portable double peak pulse laser induced plasma spectroscopy (DPP-LIPS) based on passively Q-switched Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser excitation is reported. The latter delivered structured laser pulses at a repetition rate of up to 20 Hz, including two energy peaks of about 100 mJ each with a relative temporal spacing of about 80 µs. Plasma spectra were collected using a low-cost Czerny-Turner spectrometer equipped with a non-intensified CCD (Charge-Coupled Device) array. Such a DPP-LIPS setup is technologically simpler and cheaper than the usual ones. Despite the relatively large temporal separation between the mentioned laser peaks, significant spectral intensity enhancements with respect to the usual single peak pulse configuration were observed. The amplification factor measured ranged between 2 and 10, depending on the specific emission peaks and the Q-switched configuration, and a consequent significant improvement of the detection limit of trace elements was observed. The instrument was calibrated for the quantitative analysis of copper alloy through systematic measurements carried out on reference samples and was then tested in an example archaeometric characterization of a statuette from the Egyptian Museum of Florence.
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http://dx.doi.org/10.3390/s19173634DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6749410PMC
August 2019

1064-nm-resonant gold nanorods for photoacoustic theranostics within permissible exposure limits.

J Biophotonics 2019 10 2;12(10):e201900082. Epub 2019 Jun 2.

Istituto di Fisica Applicata 'Nello Carrara', Consiglio Nazionale delle Ricerche IFAC-CNR, Sesto Fiorentino, Italy.

Therapeutic and diagnostic methods based on photomechanical effects are attracting much current attention in contexts as oncology, cardiology and vascular surgery, for such applications as photoacoustic imaging or microsurgery. Their underlying mechanism is the generation of ultrasound or cavitation from the interaction of short optical pulses with endogenous dyes or targeted contrast agents. Among the latter, gold nanorods are outstanding candidates, but their use has mainly been reported for photoacoustic imaging and photothermal treatments. Conversely, much less is still known about their value as a precision tool for photomechanical manipulations, such as to impart local damage with high spatial resolution through the expansion and collapse of microbubbles. Here, we address the feasibility of gold nanorods exhibiting a distribution of surface plasmon resonances between about 900 to above 1100 nm as a contrast agent for photoacoustic theranostics. After testing their cytotoxicity and cellular uptake, we discuss their photostability and use to mediate cavitation and the photomechanical destruction of targeted cells. We find that the choice of a plasmonic band peaking around 1064 nm is key to enhance the translational potential of this approach. With respect to the standard alternative of 800 nm, at 1064 nm, relevant regulations on optical exposure are less restrictive and the photonic technology is more mature.
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http://dx.doi.org/10.1002/jbio.201900082DOI Listing
October 2019

Raman spectrometer for the automated scan of large painted surfaces.

Rev Sci Instrum 2019 May;90(5):053101

Institute of Applied Physics "Nello Carrara" (IFAC-CNR), Florence, Italy.

In this work, a novel Raman scanner capable of performing point-to-point mapping of relatively large surface of paintings is presented. This device employs an excitation wavelength of 1064 nm, and it is equipped with a high efficiency probe in order to collect the back-scattered light from each point of analysis. The use of long depth-of-field optics as well as an autofocus system allowed maintaining the best conditions for the Raman signal acquisition during the scanning, regardless of the surface irregularities. The small dimension of the optical components and the reasonable size of mechanical parts made this instrumentation particularly suitable for on-site measurements. Finally, the Raman scanner was also equipped with an online temperature control using a thermal sensor, which allows modulating automatically the output power of the laser source in order to prevent overheating and alteration effects during the scanning process. The capabilities of the Raman scanner were evaluated scanning two valuable paintings one attributed to Ambrogio Lorenzetti and the other to Duccio da Buoninsegna of the fourteenth century.
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http://dx.doi.org/10.1063/1.5088039DOI Listing
May 2019

Advances in laser cleaning of artwork and objects of historical interest: the optimized pulse duration approach.

Acc Chem Res 2010 Jun;43(6):739-50

Istituto di Fisica Applicata Nello Carrara, Consiglio Nazionale delle Ricerche, Sesto Fiorentino (Florence), Italy.

Laser ablation has found numerous applications in biomedical and industrial settings but has not spread as quickly as a means of cleaning artwork. In this Account, we report recent advances in the study and application of laser cleaning to the conservation of cultural heritage. We focus on the solution of representative cleaning problems of encrusted stones, metals, and wall paintings that were achieved through the optimization of laser pulse duration. We begin by introducing the basic mechanisms involved in the laser ablation of stratified materials and the criteria for preventing undesired side effects to the substrate and then briefly present case studies for each of these materials. Laser interaction effects are reviewed in a schematic way, with a concise overview of the physical models needed to support intuitive interpretations of the phenomenology observed, both in laboratory tests and in practical applications on important artifacts. This approach aims to provide keys of generalization that will favor the rigorous application of laser cleaning, repeatability of the successful results reported in this work, and further dissemination and acceptance of the technique. The topics treated examine the ablation mechanisms along with the efficiency, gradualness, selectivity, and effectiveness of the technique as a function of the pulse duration of neodymium laser systems and the operating conditions. Physical modeling and experimental evidence support the selection of pulse durations of between several tens of nanoseconds and several tens of microseconds, making it possible to minimize the risk of photothermal and photomechanical effects and maximize the selectivity of the ablation process. The sections dedicated to stones and metals also deal with the important problem of discoloration, which has significantly slowed the spread of the laser cleaning technique. The well-known problem of a yellowish appearance after laser cleaning is shown to be closely related to the ablation process; it can therefore be prevented by a suitable selection of irradiation parameters. The metal surfaces investigated are amalgam gilding, gold leaf gilding, and, for the first time, silver artifacts. We also describe the criteria used for applying laser ablation techniques to restoring unique masterpieces, such as Lorenzo Ghiberti's Porta del Paradiso and Donatello's David. Furthermore, a novel and unusual cleaning approach for archaeological silver is reported. Based on underwater laser irradiation, it provides a way to prevent oxidative effects and amplify the photomechanical coupling to the hard, thick concretions that usually accompany archaeological pieces. Finally, the experimental extension of the laser cleaning approach to wall painting and its practical use in important restoration works is presented. The practical examples reveal a significant advance in perspective for the application, which was unthinkable until recently. In sum, this Account describes novel technological and methodological contributions of laser cleaning that are having a significant impact in the field of cultural heritage conservation.
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http://dx.doi.org/10.1021/ar900190fDOI Listing
June 2010

A new method based on contact surface profilometry for quantitative measurement of resorbed bone volume.

Phys Med 2005 January - March;21(1):41-6

Dept. of Clinical Physiopathology, Medical Physics Sect. University of Florence, Viale Pieraccini 6, I 50139 Florence (Italy).

Bone is a dynamic tissue. Its continuous remodeling depends on the balance between bone formation and bone resorption. These two processes are carried out by specialized cells called osteoblast and ostreoclast respectively. The osteoclastic bone resorption consists in degradation of the mineral and collagen components of bone. The study of bone turnover requires accurate assessment of osteoclastic bone resorption, that becomes even more important in pathologic bone loss due to the uncoupling between bone formation and bone resorption. Osteoclastic activity is diffucult to measure. Many techniques, generally based on the detection of the resorbing lacunae (lacunae (pits) due to the bone degradation, allow to estimate bone resorption, but none of them quantitatively and directly measures the volume of resorbed bone. We propose a reliable and relatively simple method, based on contact surfact profilometry, to evaluate directly and quantitatively the volume of resorbed bone. The method has the following advantages:
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http://dx.doi.org/10.1016/S1120-1797(05)80018-3DOI Listing
October 2012

Pirenoxine prevents oxidative effects of argon fluoride excimer laser irradiation in rabbit corneas: biochemical, histological and cytofluorimetric evaluations.

J Photochem Photobiol B 2005 Jan;78(1):35-42

Department of Preclinical and Clinical Pharmacology, University of Florence, V.le Pierraccini, 6, Florence, Italy.

The production of reactive oxygen species (ROS) associated with excimer laser irradiation is recognized as a possible cause of corneal haze following photorefractive keratectomy (PRK). Our work was aimed at investigating in vitro the oxidative effects induced by subablative laser fluences and at demonstrating the protective effectiveness of pirenoxine. Comparative trials of subablative fluence on rabbit eyes with or without 10(-5) M pirenoxine were carried out. Superoxide anion (O(2)(-)), conjugated diene (CD), and thiobarbituric acid reagent substance (TBARS) formation were analyzed. Cellular death was evaluated by flow cytometry. Histological examinations were also performed. No appraisable differences in O(2)(-),CD,andTBARS formation were detected soon after irradiation, whereas they all increased following incubation. Pirenoxine inhibited such increases. Cytofluorimetric and histological observations gave coherent results. The experimental data indicate that oxidative and toxic effects are ascribable to ROS avalanches triggered by laser irradiation-induced photodissociation and are inhibited by pirenoxine.
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http://dx.doi.org/10.1016/j.jphotobiol.2004.09.005DOI Listing
January 2005