NMR and other molecular and elemental spectroscopies for the characterization of samples from an outdoor mural painting by Siqueiros.

This study presents the use of high resolution Nuclear Magnetic Resonance (NMR) as an outstanding tool for identifying with accuracy the structure of the polymers used as binders and the additives used as plasticizers in samples from a mural painted by David Alfaro Siqueiros between 1964 and 1972, an important period in which his artistic production has not been previously studied. Additionally, the presence of some organic pigments was detected. The mural Trazos de composición piramidal currently located outside of Siqueiros' studio La Tallera, in Cuernavaca Morelos (Mexico) was an artistic experiment done by Siqueiros to test outdoor painting. Eight micro-samples of paint were thoroughly analyzed by Optical Microscopy (OM), Scanning Electron Microscopy - Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Fiber Optics Reflectance Spectra (FORS), Transmission Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance mode (FTIR-ATR) and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). Through these studies, contrasted with an historical investigation, we demonstrate that the samples present a multi-layered and complex painting system because Siqueiros made at least two versions of the painting. The multi-layered structure and the variable composition of each layer challenged the application of several analytical methodologies traditionally used for cultural heritage materials. In one sample, each layer was separated and they were studied in detail by FTIR-ATR, Py-GC/MS and NMR. This study revealed the presence of two main binders: acrylics in the first layers and nitrocellulose in the last one, also some phthalates and fatty acids were detected as additives. Inorganic pigments and fillers were identified as titanium dioxide and iron red oxide as well as diatoms and carbonates. The main contribution of this study, where NMR spectroscopy was applied for the first time in modern mural painting analysis, is the characterization of the materials used by Siqueiros during the last years of his artistic production.

Technical non-invasive study of the novo-hispanic painting the Pentecost by Baltasar de Echave Orio by spectroscopic techniques and hyperspectral imaging: In quest for the painter's hand.

This paper presents a combination of noninvasive techniques for the study of superimposed painting stages in The Pentecost, a Mexican Colonial panel painting attributed to Baltasar de Echave Orio (1558 - 1619). The application of reflected hyperspectral imaging (HSI) analysis for mapping the distribution of the pigments in the paint surface and the use of ultraviolet (UV) fluorescence photography and X-ray radiography as complementary imaging techniques provide new insights into the making process of the artwork, its manufacturing and conservation state. For a better understanding of the in situ results gathered, we studied a series of paint mock-up samples created following recipes and studio practices from art treatises. The use of spot analytical methods such as fiber optic reflectance spectroscopy (FORS) and X-ray fluorescence spectroscopy (XRF) allowed for a robust identification of the artist's materials.

Spectroscopic examination of Red Queen's funerary mask and her green stone offering from the Mayan site of Palenque, Mexico.

This work presents a non-invasive material study of the Red Queen's funerary offering via in situ infrared (FTIR) and Raman spectroscopies for mineral identification, and X-ray fluorescence spectroscopy (XRF) for elemental characterization. A second non-destructive laboratory stage on the main mask of the offering only was carried out by particle induced X-ray emission (PIXE) for further elemental analysis. The main FTIR results indicate that all of the tesserae of the main mask are composed of malachite, identified by their ν(CuO), ν(CuOH), ν1-ν4(CO32-) and δ(CO32-) infrared and T(CO32-) Raman vibrational modes. Moreover, the pupils are composed of obsidian (δ(SiOSi) and ν(SiO) infrared vibrational modes), and remarkably, jadeite was identified in the sclera of the eyes. Most of the accompanying mask's tesserae are green quartz and chalcedony (δ(SiOSi) and ν(SiO) infrared and Raman vibrational modes). The pendants are made of jadeite, while the headdress´ tesserae were identified as omphacite. The diadem and necklace's green beads were mostly jadeite, omphacite and albite. Jadeite, albite and omphacite were identified through their characteristic infrared and Raman vibrational modes: ν(SiOSi), δ(SiOSi), τ(SiO4) and AlSiO4 interactions. Yellow-orange beads in the diadem and in the pectoral are quartz. Green and blue pectoral beads are jadeite, omphacite and quartz. Limestones and shells identified in the figurine, valve and in some of the headdress and accompanying mask's tesserae, were properly classified by Raman spectroscopy, using their characteristic ν1 and ν4 (CO32-) vibrational modes for aragonite and beta-carotenes characteristic Raman shifts for Spondylus valves. These results indicate a special selection and the use of unique raw materials for the royal burial of the Red Queen, different to those used for other rulers of Palenque and other contemporary Mayan sites.

Methodology for the non-destructive characterization of jadeite-jade for archaeological studies.

The present paper proposes a methodology that complies with the requirements of identifying and characterizing jadeite (and its associated minerals) for archaeological studies, avoiding the acquisition of samples and ensuring the integrity of the object. The methodology exploits a carefully selected array of techniques (optical microscopy, UV fluorescence photography, X-Ray digital radiography, infrared and Raman spectroscopies, X-Ray fluorescence and particle induced X-ray emission spectroscopies) that, despite not definitively replacing laboratory procedures, provides a first mineral and elemental evaluation of jadeite archaeological objects. The proposed methodology was applied in the characterization of twelve different jade tones, allowing the identification of major - jadeite, albite and omphacite - and minor - pumpellyite, actinolite, analcime, rutile, grossular and titanite - mineral phases. To display its advantages and limitations, this methodology was also compared with a characterization employing specific gravity measurements and with an invasive methodology based on petrography and scanning electron microscopy with energy dispersive spectroscopy.

Identification of natural red and purple dyes on textiles by Fiber-optics Reflectance Spectroscopy.

Understanding dye chemistry and dye processes is an important issue for studies of cultural heritage collections and science conservation. Fiber Optics Reflectance Spectroscopy (FORS) is a powerful technique, which allows preliminary dye identification, causing no damage or mechanical stress on the artworks subjected to analysis. Some information related to specific light scattering and absorption can be obtained in the UV-visible and infrared range (300-1400nm) and it is possible to discriminate the kind of support fiber in the near infrared region (1000-2500nm). The main spectral features of natural dye fibers samples, such as reflection maxima, inflection points and reflection minima, can be used in the differentiation of various red natural dyes. In this work, a set of dyed references were manufactured following Mexican recipes with red dyes (cochineal and brazilwood) in order to determine the characteristic FORS spectral features of fresh and aged dyed fibers for their identification in historical pieces. Based on these results, twenty-nine indigenous textiles belonging to the National Commission for the Development of Indigenous People of Mexico were studied. Cochineal and brazilwood were successfully identified by FORS in several pieces, as well as the mixture of cochineal and indigo for purple color.

Antibiotic sensitivity patterns of actinomycetes isolated from patients of actinomycetoma.

The effectiveness of eight antibiotics against 30 human isolates of actinomycetoma agents belonging to 7 different species were tested by agar dilution and disc diffusion methods to evaluate the susceptibility patterns and to study drug resistance among the organisms. It was found that many of the isolates had developed partial or complete resistance to conventionally used antibiotics like cotrimoxazole, streptomycin and ampicillin, but almost all were sensitive to amikacin and ciprofloxacin. The two methods were equally effective for detecting sensitivity patterns of the Nocardia isolates.

Evaluation of the phenol-induced flagellar agglutination test for the identification of the cholera group of vibrios.

Applied routinely to 1081 recently isolated cultures, the phenol-induced slide-agglutination test (standard procedure) with flagellar antiserum corrently identified 98.9% of Vibrio cholerae strains of O type-I and NAG serotypes; 1.0% of cultures were unstable in phenol-saline. The incidence of instability and other types of defect was higher (7.3%) in older stock cultures. The majority of such strains were successfully tested by one of the three modified procedures. No cross-reactions were observed in 47 cultures of other species including the halophilic vibrios. Only one out of the 1205 cultures of V. cholerae tested by all procedures reacted negatively; this strain was found to lack functional flagella. These results establish the significance of flagellar specificity as a classificatory determinant in V. cholerae, and the fidelity and utility of the phenol test in routine bacteriology.

Effect of sulfadoxine on transmission of Vibrio cholerae infection among family contacts of cholera patients in Calcutta.

Sulfadoxine, a long-acting sulfonamide, and tetracycline were compared as regards their effectiveness in reducing transmission of cholera infection among the contacts of cholera patients in Calcutta. A total of 109 healthy family contacts of confirmed hospitalized cholera patients were treated with a single oral dose of sulfadoxine graded according to age. Another similar group of 101 contacts received 6 divided doses of oral tetracycline over a period of 3 days. All these contacts were bacteriologically examined for 15 days. Results showed that tetracycline was effective in significantly reducing the load of cholera infection from the 2nd to 6th day, while sulfadoxine was effective from the 3rd to the 6th day. The advantages and disadvantages of the two drugs as chemoprophylactic agents in cholera are discussed.