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Pozzi F.,Solomon R. Guggenheim Museum | Leona M.,Metropolitan Museum of Art
Journal of Raman Spectroscopy | Year: 2016

Since its introduction in the cultural heritage field, nearly 30 years ago, surface-enhanced Raman spectroscopy (SERS) has emerged as a promising analytical technique that is particularly suitable for the detection and identification of organic colorants. Its great molecular selectivity and specificity, and unparalleled sensitivity compared to other instrumental methods, have allowed researchers to successfully characterize a wide number of natural dyes and a few synthetic ones in microscopic samples from objects of artistic, historical, and archaeological significance. Continued research over the course of the past decade has led to the construction of comprehensive databases of dyes, whose adsorption and spectral properties have been investigated at length; to the comparative study of the efficiency and performance of various metal substrates; and to the evaluation of several sample treatment methods and ad-hoc analytical protocols. In addition, recent literature in the field of SERS for art and archaeology has described instrumentation and technique advancements aimed at solving the unique challenges posed by the analysis of irreplaceable objects, namely, quasi non-destructive sampling, spatial resolution improvement, examination of insoluble compounds, and resolution of dye mixtures. Reviewing the most salient methodological and technological milestones that have traced the history of SERS for cultural heritage to date, the present article is intended as a practical resource for those researchers who would like to undertake systematic characterization of organic colorants from artworks using this powerful technique. Copyright © 2015 John Wiley & Sons, Ltd. Source


Casadio F.,School of the Art Institute of Chicago | Leona M.,Metropolitan Museum of Art | Lombardi J.R.,City University of New York | Van Duyne R.,Northwestern University
Accounts of Chemical Research | Year: 2010

Organic dyes extracted from plants, insects, and shellfish have been used for millennia in dyeing textiles and manufacturing colorants for painting. The economic push for dyes with high tinting strength, directly related to high extinction coefficients in the visible range, historically led to the selection of substances that could be used at low concentrations. But a desirable property for the colorist is a major problem for the analytical chemist; the identification of dyes in cultural heritage objects is extremely difficult. Techniques routinely used in the identification of inorganic pigments are generally not applicable to dyes: X-ray fluorescence because of the lack of an elemental signature, Raman spectroscopy because of the generally intense luminescence of dyes, and Fourier transform infrared spectroscopy because of the interference of binders and extenders. Traditionally, the identification of dyes has required relatively large samples (0.5-5 mm in diameter) for analysis by high-performance liquid chromatography. In this Account, we describe our efforts to develop practical approaches in identifying dyes in works of art from samples as small as 25 μm in diameter with surface-enhanced Raman scattering (SERS). In SERS, the Raman scattering signal is greatly enhanced when organic molecules with large delocalized electron systems are adsorbed on atomically rough metallic substrates; fluorescence is concomitantly quenched. Recent nanotechnological advances in preparing and manipulating metallic particles have afforded staggering enhancement factors of up to 1014. SERS is thus an ideal technique for the analysis of dyes. Indeed, rhodamine 6G and crystal violet, two organic compounds used to demonstrate the sensitivity of SERS at the single-molecule level, were first synthesized as textile dyes in the second half of the 19th century. In this Account, we examine the practical application of SERS to cultural heritage studies, including the selection of appropriate substrates, the development of analytical protocols, and the building of SERS spectral databases. We also consider theoretical studies on dyes of artistic interest. Using SERS, we have successfully documented the earliest use of a madder lake pigment and the earliest occurrence of lac dye in European art. We have also found several examples of kermes and cochineal glazes, as well as madder, cochineal, methyl violet, and eosin lakes, from eras ranging from ancient Egypt to the 19th century. The ability to rapidly analyze very small samples with SERS makes it a particularly valuable tool in a museum context. © 2010 American Chemical Society. Source


Centeno S.A.,Metropolitan Museum of Art
Journal of Raman Spectroscopy | Year: 2016

The aim of the present article is to highlight publications that illustrate some advances in the application of Raman spectroscopy to investigate materials typically observed in manuscripts, drawings, prints, and paintings in museums' and cultural institutions' collections, and to discuss some of the challenges and future prospects. Copyright © 2015 John Wiley & Sons, Ltd. Source


News Article
Site: http://news.yahoo.com/science/

There's a new conspiracy theory out there, but instead of invoking big government or aliens, it questions whether there's a laptop carved into an ancient Greek statue. That's right — there's a theory out there saying that a funerary statue of a woman, dated to about 100 B.C., shows her looking at a modern laptop or a handheld digital device. The theory, proposed by the anonymous YouTube user StillSpeakingOut, ventures that the ancient Oracle of Delphi may have foreseen the invention of laptops, and told people about it. "Just so we are clear, I'm not saying that this relief was depicting an ancient laptop computer," StillSpeakingOut said in the 100-second-long video. [Supernatural Powers? Tales of 10 Historical Predictions] But "Greek tales about the Oracle of Delphi, which was supposed to allow the priests to quote-unquote connect with the gods and retrieve advanced information of various aspects," made him wonder whether the statue represented a prediction, StillSpeakingOut said. In fact, the object depicted on the statue does look something like a laptop, said Jeffrey Spier, the senior curator of antiquities at the J. Paul Getty Museum in Malibu, California, which owns the statue. But, of course, it's not, Spier said. Instead, the object may be a jewelry box, a shallow chest or possibly a hinged mirror, as "we have hinged mirrors from this time period," Spier said. Perhaps it's a box containing incense, although there's no incense burner in the scene, so that may be a stretch, he added. Another historian debunked StillSpeakingOut's idea that the so-called laptop has USB ports in its side. "The 'USB ports' are drill holes for the attachment of a bronze object, or perhaps a separate piece of marble," said Jeff Hurwit, a professor of art history and classics at the University of Oregon. The statue, officially called "Grave Naiskos of an Enthroned Woman with an Attendant," depicts a well-dressed woman lounging on a cushioned armchair and reaching out "to touch the lid of a shallow chest held by a servant girl," according to the J. Paul Getty Museum. Funerary reliefs, fashioned out of marble like this one, were common in ancient Greece, going in and out of style over the years, Spier told Live Science. Such reliefs start occurring in the archaeological record in the sixth century B.C. and continue until about the first century B.C. These funerary statues would have sat above graves of the deceased, and are called naiskos, which are small temples dedicated to the deceased, Spier said. This one would have likely had a triangular top, and probably had the departed woman's name painted on top, he said. "We have a number [of naiskos] in the museum," Spier said. "They show young girls with their toys or with pets. They are very nostalgic and sympathetic." However, guests won't see the "enthroned woman" naiskos anytime soon at the Getty. The museum lent the statue to the Metropolitan Museum of Art in New York City, where it will go on display April 18 for an exhibit called, "Pergamon and the Hellenistic Kingdoms of the Ancient World." Guests visiting the Met can decide for themselves whether they think the statue shows a laptop, but the experts have already made up their minds. "Seriously?" Hurwit said. "The 'laptop' is in fact a shallow box or lidded tray from which the woman is about to select a piece of jewelry, as is commonly shown in grave reliefs like this one." However, this isn't the only conspiracy about modern technology showing up in yesteryear. In 2010, a similar flurry arose concerning a woman in a 1928 Charlie Chaplin film holding an object that looked like a cellphone. But that mystery object was likely an ear trumpet, used to help the woman hear, experts said. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.


News Article | September 12, 2016
Site: http://www.chromatographytechniques.com/rss-feeds/all/rss.xml/all

A team of North Carolina-based researchers helped unearth more clues this summer about the ancient Nabatean city of Petra in Jordan. As part of a larger excavation at the site, the group of North Carolina State University and East Carolina University faculty and students discovered two marble statues of the mythological goddess Aphrodite -- artifacts that dig co-director Tom Parker describes as "absolutely exquisite." Parker, a professor of history at NC State, said the team found the pieces while excavating domestic structures in Petra's North Ridge area during May and June. "I've been doing field work in the Middle East for 45 years and never had a find of this significance," Parker said. "These are worthy of display at the Louvre Museum or the Metropolitan Museum of Art." The statues, which also feature the mythological god Cupid, are largely intact from pedestal to shoulders. Both statue heads and much of their upper extremities were also recovered at the site and will be restored. This year's dig marked the third season of the Petra North Ridge Project, an initiative aimed at uncovering clues about the ancient city's non-elite population. So while the statues are remarkable finds, they're also somewhat unexpected. The team was digging what they thought was an ordinary home this summer when they came across something much more. The house was more like an urban villa, Parker said, equipped with its own sophisticated bath house. The team found the fragmented statues next to the home's staircase. "Even though they weren't exactly what we were looking for, these finds still tell us a lot about the population," Parker said. The marble statues are Roman in style, which provide additional insight to the cultural impact of Rome's annexation of Nabataea in 106 A.D. "The Nabateans were true geniuses in many ways, in part because they were ready and willing to assimilate to and adopt elements of other cultures around them," Parker said. "They adopted a lot of Egyptian culture when they were neighbors. When Romans took over, they were open to Roman influence." The dig team, which Parker co-directs with bioarchaeologist Megan Perry, professor of anthropology at ECU, found a wealth of other artifacts that shed more light on Nabatean daily life. Digging one other domestic structure and three rock-cut shaft tombs, the researchers discovered installations for cooking and storage, occupational remains such as pottery and animal bones, an iron sword, ceramic oil lamps and human bones intermixed with personal adornments and jewelry. "The human remains and mortuary artifacts from Petra provide perspectives not only on Nabataean concepts of death, but also their biological histories while alive," Perry said.

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