Abstract: This chapter lays out a conservation timeline, from past to future, for the Amsterdam version of Van Gogh's Sunflowers. It starts by considering the restoration history of the painting in order to assess its current physical state, and looks ahead to formulate an appropriate strategy for future conservation treatment and display. Due attention is paid to the two recorded episodes of restoration performed in 1927 and 1961 by the Dutch restorer, Jan Cornelis Traas. Based on physical and chemical investigation of Sunflowers we attempt to reconstruct what these former treatments (which are barely documented) entailed and consider the repercussions for the present condition of the painting. The former interventions by Traas also serve as a benchmark to reflect on current choices made, highlighting the extent to which ideas and methodologies have continued to evolve over the past century as conservation has moved further away from being a singularly craft-based activity to become an established historical and scientific discipline underpinned by ethical guidelines. Jan Cornelis Traas (1898–1984) As mentioned, the two main recorded interventions to the Amsterdam Sunflowers may be associated with the Dutch restorer, Jan Cornelis Traas, who treated the picture in 1927, close to the start of his career, and again in 1961, shortly before he retired. Traas was the first restorer to be appointed at the Mauritshuis in The Hague where he worked from 1931 to 1962 and treated hundreds of paintings, including iconic masterpieces such as Girl with a Pearl Earring by Johannes Vermeer. Yet despite the magnitude and importance of his restoration oeuvre, J.C. Traas (as he is usually referred to in surviving documents), has remained somewhat obscure. He is shown here in the only known surviving photograph of him at work, shortly before he retired (fig. 7.1). Unlike his illustrious contemporaries, A. Martin de Wild (1899–1969) and Helmut Ruhemann (1891–1973), for example, Traas did not publish anything, he appears to have kept no records of his work and no personal archive is known. However, the study of some newly discovered historical documents, combined with physical examination of Sunflowers and a large number of other works he treated, allows us to recover an idea of his working practices and approaches viewed within the context of his day.

Abstract: The ability to detect low concentrations of protein biomarkers is crucial for the early-stage detection of many diseases and therefore indispensable for improving diagnostic devices for healthcare. Here, we demonstrate that by integrating DNA nanotechnologies like DNA origami and aptamers, we can design innovative biosensing concepts for reproducible and sensitive detection of specific targets. DNA origami structures decorated with aptamers were studied as a novel tool to structure the biosensor surface with nanoscale precision in a digital detection bioassay, enabling control of the density, orientation, and accessibility of the bioreceptor to optimize the interaction between target and aptamer. DNA origami was used to control the spatial distribution of an in-house-generated aptamer on superparamagnetic microparticles, resulting in an origami-linked digital aptamer bioassay to detect the main peanut antigen Ara h1 with 2-fold improved signal-to-noise ratio and 15-fold improved limit of detection compared to a digital bioassay without DNA origami. Moreover, the sensitivity achieved was 4 orders of magnitude higher than commercially available and literature-reported enzyme-linked immunosorbent assay techniques. In conclusion, this novel and innovative approach to engineer biosensing interfaces will be of major interest to scientists and clinicians looking for new molecular insights and ultrasensitive detection of a broad range of targets, and, for the next generation of diagnostics.

Abstract: The control of damage to individual environmental particles by a laser beam during Raman spectroscopy carried out in ambient air is generally well understood. The nature and control of damage under vacuum conditions (e.g. in the scanning electron microscopy with energy X-ray detection combined with micro-Raman spectroscopyinterfaced SEM-EDX/MRS) are more complex and less well comprehended. The physical and chemical processes that affect the damage caused to small particles by lasers still remain somewhat unclear, but certainly the atmosphere (vacuum/air) and the beam intensity have very significant influences. Furthermore, it has been determined that some particles (e.g. haematite), although stable under an electron beam, are damaged by the laser beam, hampering their analysis. Additionally, when simultaneous analyses by SEM/EDX and MRS are considered, the correct choice of the collection surface plays a crucial role. As a result, the following collection substrates were tested to determine their influence on the laser beam damage process to the particle: silver and aluminium foils and silicon wafers. A test study was performed using artificial examples of haematite (Fe2O3) particles. Exposure of Fe2O3 particles in vacuum to 514- and 785-nm laser radiation often leads to their melting, transformation and evaporation. The dependence of the damage caused by the laser beam on the particle structure is reported here. Molecular and crystallographic changes have also been revealed. Formation of magnetite (as an effect of re-crystallisation) and Raman inactive structures was detected.

Abstract: We present a decision-support system that guides heritage guardians in selecting mitigation actions to improve the indoor air quality and thus the preservation conditions of indoor collections in heritage buildings. This contribution shows that it is feasible to build a decision support system dedicated to preventive conservation when the following barriers are overcome: 1) simultaneous measurement of a wide range of environmental parameters in order to detect a larger number of undesired situations; 2) development of an algorithm to perform reproducible indoor air quality assessments; and 3) transformation of the air quality assessment into a graph that can be read intuitively without causing a wide variation of interpretations among stakeholders. An important aspect of the decision support system is that it reduces several sources of uncertainty that hamper reliable indoor air quality assessments. The possibilities of such a system are illustrated with a measurement campaign in a church where a heating system has been installed and used for the first time.

Abstract: It is well known that airborne particulate matter (APM) has an impact on our cultural heritage. A limited number of articles have been published on the sequential application of elemental and molecular techniques to estimate the degradation potential of APM in environments of cultural heritage importance, and most of these were concerned with indoor environments. The Alhambra monument (Granada, Spain) represents one of the grandest and finest examples of Islamic art and architecture from the Middle Ages. As part of an air quality investigation, two sets of APM were collected at the Hall of the Ambassadors and characterised to determine its potential degradation profile. These were analysed by means of micro-Raman spectroscopy (MRS) and electron probe microanalysis with X-ray detection (EPXMA). The Raman data indicated the presence of various mixed salts of acidic and/or hygroscopic nature, such as sodium and ammonium nitrates and sulfates, especially in the finer fraction. Automated EPXMA estimated this fraction to be as high as 50%. Apart from the potential chemical attack, the soiling due to carbonaceous matter deposition is a real concern. Soot was identified by MRS and EPXMA in all size fractions, reaching values of up to 55%, and was often intertwined with soluble inorganic salts. Ongoing degradation of the pigments is implicated by the presence of brightly coloured particles. MRS and molar abundance ternary diagrams elicited the chemical structure of individual APM so that the degradation potential could be established.

Abstract: Amphetamine (AMP) is posing critical issues in our society being one of the most encountered drugs-of-abuse in the current illicit market. The continuous drug production in Europe urges the development of new tools for the rapid on-site determination of illicit drugs such as AMP. However, the direct electrochemical detection of AMP is a challenge because the molecule is non-electroactive at the potential window of conventional graphite SPEs. For this reason, a derivatization step is needed to convert the primary amine into an electroactive oxidizable group. Herein, the rapid electrochemical detection of AMP in seized samples based on the derivatization by 1,2-naphthoquinone-4-sulfonate (NQS) is presented by using square wave voltammetry (SWV) at graphite screen-printed electrodes (SPEs). First, a detailed optimization of the key parameters and the analytical performance is provided. The method showed a sensitivity of 7.9 µA mM-1 within a linear range from 50 to 500 µM, a limit of detection of 22.2 µM, and excellent reproducibility (RSD = 4.3%, n = 5 at 500 µM). Subsequently, the effect of NQS on common cutting agents for the selective detection of AMP is addressed. The comparison of the method with drugs-of-abuse containing secondary and tertiary amines confirms the selectivity of the method. Finally, the concept is applied to quantify AMP in 20 seized samples provided by forensic laboratories, exhibiting an accuracy of 97.3 ± 10.5%. Overall, the fast analysis of samples with the electrochemical profiling of derivatized AMP exhibits a straightforward on-site screening aiming to facilitate the tasks of law enforcement agents in the field.