Novel application of liquid chromatography/mass spectrometry for the characterization of drying oils in art: Elucidation on the composition of original paint materials used by Edvard Munch (1863-1944)

Modern oil paints, introduced at the beginning of the 20th century, differ from those classically used in antiquity in their chemical and compositional features. The main ingredients were still traditional drying oils, often used in mixtures with less expensive oils and added with several classes of additives. Consequently, detailed lipid profiling, together with the study of lipid degradation processes, is essential for the knowledge and the conservation of paint materials used in modern and contemporary art.A multi-analytical approach based on mass spectrometry was used for the study of original paint materials from Munch's atelier, owned by the Munch Museum in Oslo. The results obtained in the analysis of paint tubes were compared with those obtained by characterizing a paint sample collected from one of the artist's sketches for the decoration of the Festival Hall of the University of Oslo (1909-1916).Py-GC/MS was used as screening method to evaluate the presence of lipid, proteic or polysaccaridic materials. GC/MS after hydrolysis and derivatization allowed us to determine the fatty acid profile of the paint tubes, and to evaluate the molecular changes associated to curing and ageing. The determination of the fatty acid profile is not conclusive for the characterization of complex mixtures of lipid materials, thus the characterization of the triglyceride profiles was performed using an analytical procedure based on HPLC-ESI-Q-ToF.This paper describes the first application of HPLC-ESI-Q-ToF for the acquisition of the triglyceride profile in a modern paint sample, showing the potentialities of liquid chromatography in the field of lipid characterization in modern paint materials. Moreover, our results highlighted that the application of this approach can contribute to address dating, authenticity and conservation issues relative to modern and contemporary artworks

CHARACTERIZATION AND COMPARISON OF SOLAR SELECTIVE COATINGS BETWEEN NI-AL AND NI-CO ON ALUMINUM SUBSTRATE

An ideal solar absorber surface coating must have good optical properties like high solar absorptance with minimum solar emittance. Development of new coating is fabricated by embedding metallic particles composed of a nickelaluminium (NiAl) alloy into the black paint as well as solar selective black nickel-cobalt (NiCo) electroplating on aluminium alloys with nickel undercoat is done. Characterization of such solar selective surface coatings are done and compared with commercial black paint. A new and affordable solar selective surface coating having higher solar absorption efficiency with low in-frared emittance compared to the commercial black paint coating used in most ordinary solar water heating systems has been developed. Characterization of coating includes Optical properties studies of coatings, Surface morphology and XRD studies, and solar water heater performance with new coatings. https://journalnx.com/journal-article/2015036

Passivation of carbon steel using intelligent epoxy paint

This paper presents the production of an epoxy paint associated with a determined concentration of PAni emeraldine base binder, in order to increase dispersion of PAni polymer chains in the paint allow physical contact between PAni chains, the electrolytic medium, and the metal of interest. The coating called Intelligent Epoxy Paint (IEP) seeks to potentialize the electrolytic capacity of PAni to produce passivation, differentiated research which uses PAni in oxidized and conductive form as paint pigment that needs high PAni concentrations. The physicochemical characterization and morphological presented results that indicate the preservation of the desirable properties of PAni in order to make the passivation process possible. The electrochemical tests showed the passivation and/or maintenance of the passivation of the metal of interest, without the need to apply an external current

Qualitative THM-GC-MS analysis of proteins and amino acids in rock painting binders

A vital step to radiocarbon dating rock paintings involves the characterization of organic material in the paint. Using THM-GC-MS we have created a library of mass spectrometric data on possible organic binders, to compare to authentic paint samples. To reduce interference from contaminants and the mineral background, we are developing a simple purification technique to extract proteins and carbohydrates from these samples. Separating the organics can greatly enhance our results for GC-MS identification and subsequent radiocarbon analysis by accelerator mass spectroscopy

Fixed speed competition on the configuration model with infinite variance degrees: equal speeds

We study competition of two spreading colors starting from single sources on the configuration model with i.i.d. degrees following a power-law distribution with exponent $\tau\in (2,3)$. In this model two colors spread with a fixed and equal speed on the unweighted random graph. We analyse how many vertices the two colors paint eventually. We show that coexistence sensitively depends on the initial local neighborhoods of the source vertices: if these neighborhoods are `dissimilar enough', then there is no coexistence, and the `loser' color paints a polynomial fraction of the vertices with a random exponent. If the local neighborhoods of the starting vertices are `similar enough', then there is coexistence, i.e., both colors paint a strictly positive proportion of vertices. We give a quantitative characterization of `similar' local neighborhoods: two random variables describing the double exponential growth of local neighborhoods of the source vertices must be within a factor $\tau-2$ of each other. Both of the two outcomes happen with positive probability with asymptotic value that is explicitly computable. This picture reinforces the common belief that location is an important feature in advertising. This paper is a follow-up of the similarly named paper that handles the case when the speeds of the two colors are not equal. There, we have shown that the faster color paints almost all vertices, while the slower color paints only a random sub-polynomial fraction of the vertices.Comment: 62 pages, 11 figure

Identity and connections within medieval heritage: color in the illuminated manuscript through the eyes of the molecular sciences and humanities

The characterization and identification of organic dyes is still a challenge within the field of Conservation Science. By exploring the potentialities of microspectrofluorimetry combined with chemometrics, this doctoral project provides the identification of red organic colorants and a comprehensive knowledge of the making of medieval paints. Microspectrofluorimetry (in the visible) allows the simultaneous acquisition of excitation and emission spectra, offering high sensitivity and selectivity combined with good spatial resolution and the possibility of in-depth profiling, which facilitates an accurate identification of dyes and lake pigments. Although lacking the fingerprint capability of vibrational spectra, it offers valuable knowledge into the paint formulation. Recipes’ specificities can provide insight into chronological and location particularities, such as scriptoria, enabling a better understanding of the making of the artists’ materials. The first part focuses on the development and testing of modeling strategies applied to i) a database of historically accurate reproductions of four natural red colorants namely brazilwood, cochineal, kermes and lac dye, used during the Middle Ages; ii) data from artworks, to address the difficulty of analyzing centuries old paints. The first confirmed the potential for microspectrofluorimetry in the assessment of the chromophore’s environment, i.e., the paint formulation, while the second explored the intricacies of the ‘original’ colors and the effectiveness of this methodology to explore similarities between naturally aged paints. This project proves the ability of microspectrofluorimetry as a powerful technique for the characterization of dyes and lake pigments. The historical reconstructions database allowed to pinpoint the main recipes of cochineal lake pigments from the 19th century Winsor & Newton’s database. The artworks database allowed to better understand recipe specificities and for the first time, we could pinpoint a formulation in which lac dye and brazilwood chromophores are admixed, in manuscripts from the Alcobaça scriptorium. In the second part, the methodology developed was tested in two case studies: the Ajuda Songbook and a group of Islamic manuscripts. The first, the oldest of the surviving Galician-Portuguese songbooks, is an unfinished illuminated manuscript, of which there is no knowledge of the circumstances of its production or the reason why it was never finished. The combination of a multi-analytical approach with the methodology developed in this project enabled the complete molecular characterization of the paint colors. It was shown the skillful construction of the paint layers and the richness of the chromatic palette, which demonstrates the desire and the resources to produce a luxurious manuscript. The methodology allowed to propose a production date for the Ajuda Songbook, in which the presence of brazilwood lake pigment and mosaic gold indicates a 14th century date, while the use of orpiment yellow pushes the date back into the 13th century. The second case study is a group of Islamic manuscripts (12th – 15th c.), from Timbuktu, Mali, which due to their rescue and conservation have allowed the study of their materials and techniques. For the first time, the richness and specificities of the paint formulations used were disclosed. It was possible not only to provide an unequivocal molecular characterization of the red colorant, lac dye but also to ascribe specific recipes to the different paint colors. Interestingly, the comparison with the artworks’ database has shown similarities with lac dye formulations found in Portuguese medieval illuminations. Moreover, the full characterization of the paint materials has also revealed severe degradation of the binding media. This approach will allow for better informed decision-making in the conservation process of these manuscripts. The synergy between the multi-analytical approach for the analysis of medieval manuscripts and the new methodology for the study of organic colorants was essential to the study of both case studies. The confocal spectrofluorimetry set-up used, as well as the expertise in the characterization of artworks, enabled in-depth knowledge into the construction of color paints, well beyond the identification of the single fluorophore

Scan and paint: theory and practice of a sound field visualization method

Sound visualization techniques have played a key role in the development of acoustics throughout history. The development of measurement apparatus and techniques for displaying sound and vibration phenomena has provided excellent tools for building understanding about specific problems. Traditional methods, such as step-by-step measurements or simultaneous multichannel systems, have a strong tradeoff between time requirements, flexibility, and cost. However, if the sound field can be assumed time stationary, scanning methods allow us to assess variations across space with a single transducer, as long as the position of the sensor is known. The proposed technique, Scan and Paint, is based on the acquisition of sound pressure and particle velocity by manually moving a P-U probe (pressure-particle velocity sensors) across a sound field whilst filming the event with a camera. The sensor position is extracted by applying automatic color tracking to each frame of the recorded video. It is then possible to visualize sound variations across the space in terms of sound pressure, particle velocity, or acoustic intensity. In this paper, not only the theoretical foundations of the method, but also its practical applications are explored such as scanning transfer path analysis, source radiation characterization, operational deflection shapes, virtual phased arrays, material characterization, and acoustic intensity vector field mapping

Historical Stained Glass Painting Techniques Technology and preservation

The aim of this project is the study of the painting techniques applied on stained glass, namely blue enamels, sanguine red and grisaille. The research and interpretation of several historical treatises dated to between the 12th and the 18th centuries was performed, with a study of the production technology of the selected painting techniques, from the preparation of the pigment to the preparation of the paint. With this in mind, selected raw materials used in the productions of blue enamels were characterized, followed by the reproduction of selected historical recipes of blue enamels, sanguine red and grisaille. Parameters such as firing temperature, grinding and binding agents used to apply the paint on glass were considered. The methodology selected was based on the chemical and morphological characterization of both reproduced powder and paint samples by means of a multi-analytical approach. In addition to the reproduction of the selected painting techniques, corrosion studies of blue enamel powder and paint samples were performed in order to provide new insights on the corrosions mechanisms involved. The results obtained were compared with selected painted stained-glass fragments from Portuguese collections, mainly the ones located in Batalha Monastery, Charola from Convento de Cristo in Tomar and Pena National Palace in Sintra. The present study concluded that the choice of the raw materials to the production of the paint, the binder used to apply the paint, and parameters such as firing temperature and heating rate, had an impact on the outcome, resulting on a better adhesion of the paint layer to the base glass. The use of zaffer as a colouring agent does not allow determination of the outcome of the paint, while adding powdered glass such as smalt gives to the glass painter the opportunity to know the final result before firing. As for sanguine red paint, it is concluded that the final outcome of the paint is strongly influenced by the heating rate. In addition, the use of gum arabic as a binder, or in the pigment itself, provides a better adhesion of the paint layer to the base glass. Regarding the grisaille painting, the main differences between the recipes lay on the composition of the lead-based glass and on the ratios between this and the colouring agents. Furthermore, it was also possible to conclude that there is an evolution of the morphology of the grisailles towards a higher homogeneity of the surface. The corrosion studies performed on blue enamels allowed to conclude that with the lixiviation of the alkaline components of the enamel, cobalt will be influenced by other neighbouring ions, leading to a change of colour. In some cases, Pb2+ ions may also be the responsible for this colour change, with the formation of lead white. The results obtained were in a good agreement with the characterization of the selected case studies, evidencing the importance of the intersection between the written sources and the laboratory work

Surface MIMO: Using Conductive Surfaces For MIMO Between Small Devices

As connected devices continue to decrease in size, we explore the idea of leveraging everyday surfaces such as tabletops and walls to augment the wireless capabilities of devices. Specifically, we introduce Surface MIMO, a technique that enables MIMO communication between small devices via surfaces coated with conductive paint or covered with conductive cloth. These surfaces act as an additional spatial path that enables MIMO capabilities without increasing the physical size of the devices themselves. We provide an extensive characterization of these surfaces that reveal their effect on the propagation of EM waves. Our evaluation shows that we can enable additional spatial streams using the conductive surface and achieve average throughput gains of 2.6-3x for small devices. Finally, we also leverage the wideband characteristics of these conductive surfaces to demonstrate the first Gbps surface communication system that can directly transfer bits through the surface at up to 1.3 Gbps.Comment: MobiCom '1

Nanoscale Mapping of Recombinant Viral Proteins: From Cells to Virus-Like Particles

Influenza recombinant proteins and virus-like particles (VLPs) play an important role in vaccine development (e.g., CadiFluS). However, their production from mammalian cells suffers from low yields and lack of control of the final VLPs. To improve these issues, characterization techniques able to visualize and quantify the different steps of the process are needed. Fluorescence microscopy represents a powerful tool able to image multiple protein targets; however, its limited resolution hinders the study of viral constructs. Here, we propose the use of super-resolution microscopy and in particular of DNA-point accumulation for imaging in nanoscale topography (DNA-PAINT) microscopy as a characterization method for recombinant viral proteins on both cells and VLPs. We were able to quantify the amount of the three main influenza proteins (hemagglutinin (HA), neuraminidase (NA), and ion channel matrix protein 2 (M2)) per cell and per VLP with nanometer resolution and single-molecule sensitivity, proving that DNA-PAINT is a powerful technique to characterize recombinant viral constructs