Band 4, Heft 7 -

In 2009 the Indianapolis Museum of Art acquired Fernando Brizio’s contemporary ceramic , Painting a Fresco with Giotto #3 , as part of its effort to grow a collection of modern and contemporary European design objects. The artwork comprises an unglazed white faience vase that has been pierced with 30 brightly colored felt-tip markers whose dried ink stains create a whimsical polka-dot surface. The vase immediately joined a traveling exhibition, and when it returned to the museum after nearly a year of display, many of the ink spots had faded dramatically, some having nearly vanished. Technical analysis was undertaken to (1) determine the cause of the fading and the composition of its Giotto brand Turbocolor markers, (2) to determine the future fading potential of the object, and (3) to suggest new safeguards to protect this and similar objects from future damage. Non-destructive analysis of the vase using Raman spectroscopy proved challenging due to the overall application of an acrylic varnish by the artist and the intense fluorescence of many of the marker inks. Using liquid chromatography with mass spectrometry on surrogate pens acquired in 2014, the 30 markers utilized in the object were ultimately determined to contain 9 primary synthetic dyes and numerous synthetic byproducts. The inks are comprised of food colorants, which accounts for their rapid fading. In situ microfade testing showed that the vase is still extremely light sensitive and will fade further under even the most stringent lighting protocols. An artist interview provided valuable information about Brizio‘s thoughts concerning the life of these objects, his working methods, and the interpretation of the Giotto series of ceramics. The artwork has since been deaccessioned from the museum’s collection but has taken on a new role in gallery didactics focused on the materials of modern design and the ephemeral and changing nature of some artworks. This project highlights the urgency of characterizing the fading rate of potentially light sensitive modern art or directly identifying the colorants used in contemporary artworks prior to their first exhibition.

Laser-induced breakdown spectroscopy (LIBS) is a versatile analytical technique that can be used to probe the elemental composition of materials in diverse types of heritage samples, objects or monuments. The main physical principles underlying LIBS are presented along with analytical figures of merit and technical details concerning instrumentation. In practice, LIBS analysis does not require any sample preparation and the technique is nearly non-invasive, offering close to microscopic spatial resolution and the possibility for depth profile analysis. These features are, at present, available in a number of compact or transportable instruments that offer versatility and enable the use of LIBS for the analysis of a broad variety of objects/samples at diverse locations and this can be highly valuable at several stages of archaeological investigations and conservation campaigns. Representative examples are presented indicating how LIBS has been used to obtain compositional information for materials in the context of archaeological science, art history and conservation.

This chapter discusses the rationale behind the bitter sensation elicited by chemical compounds, focusing on natural products. Emphasis has been placed on a brief presentation of BitterDB (the database of bitter compounds), along with available methods for the prediction of bitterness in compounds. The fundamental basis for explaining bitterness has been provided, based on the structural features of human bitter taste receptors and have been used to shed light on the mechanistic role of a few out of the 25 known human taste receptors to provide the foundation for understanding how bitter compounds interact with their receptors. Some case studies of ligand-based prediction models based on 2D fingerprints and 3D pharmacophores, along with machine learning methods have been provided. The chapter closes with an attempt to establish the relationship between bitterness and toxicity.

The field of photoredox chemistry is dominated by ruthenium- or iridium based metal complexes or organic dyes that are employed as catalysts. Other metal based coordination compounds provide a cost efficient alternative, however, the much shorter excited lifetimes generally observed for such complexes make their application more challenging. Nevertheless, a growing number of successful examples with metal complexes based on chromium, iron, nickel, zirconium, cerium, rhenium, platinum, uranium, and especially on copper exist, which is being reviewed in this chapter.

Total reflection X-ray fluorescence (TXRF) spectrometry is a non-destructive and surface sensitive multi-element analytical method based on energy dispersive X-ray fluorescence spectrometry with detection limits in the lower picogram range. It utilizes the total reflection of the primary X-ray beam at or below the critical angle of incidence. At this angle, the fluorescence intensity is substantially enhanced for samples present as small granular residue or as thin homogenous layer deposited at the surface of a thick substrate. Generally, two types of application exist: micro- and trace-analysis as well as surface and thin-layer analysis. For micro- and trace-analysis, a small amount of the solid or liquid sample is deposited on an optically flat substrate, typically quartz or polycarbonate. The dried residue is analyzed at a fixed angle setting slightly below the critical angle. Quantification is carried out by means of internal standardization. For surface and thin-layer analysis, the surface of an optically flat substrate is scanned. Variations of the incident angle of the primary X-ray beam provide information about the type and sometimes also the amount of material present at or slightly below the surface of the substrate. Major fields of application are environmental samples, biological tissues, objects of cultural heritage, semiconductors and thin-layered materials and films.

A large number of natural products, especially those used in ethnomedicine of malaria, have shown varying in vitro antiplasmodial activities. Facilitating antimalarial drug development from this wealth of natural products is an imperative and laudable mission to pursue. However, limited manpower, high research cost coupled with high failure rate during preclinical and clinical studies might militate against the pursuit of this mission. These limitations may be overcome with cheminformatic techniques. Cheminformatics involves the organization, integration, curation, standardization, simulation, mining and transformation of pharmacology data (compounds and bioactivity) into knowledge that can drive rational and viable drug development decisions. This chapter will review the application of cheminformatics techniques (including molecular diversity analysis, quantitative-structure activity/property relationships and Machine learning) to natural products with in vitro and in vivo antiplasmodial activities in order to facilitate their development into antimalarial drug candidates and design of new potential antimalarial compounds.