Assessing Mechanochemical Properties of Acrylonitrile Butadiene Styrene (ABS) Items in Cultural Heritage Through a Multimodal Spectroscopic Approach.

A multimodal spectroscopic approach is proposed to correlate the mechanical and chemical properties of plastic materials in art and design objects, at both surface and subsurface levels, to obtain information about their conservation state and to monitor their degradation. The approach was used to investigate the photo-oxidation of acrylonitrile butadiene styrene (ABS), a plastic commonly found in many artistic and design applications, using ABS-based LEGO bricks as model samples. The modifications of the chemical and viscoelastic properties of ABS during photoaging were monitored by correlative Brillouin and Raman microspectroscopy (BRaMS), combined with portable and noninvasive broad-range external reflection infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) relaxometry, directly applicable in museums.

A Thermal Analytical Study of LEGO Bricks for Investigating Light-Stability of ABS.

Acrylonitrile butadiene styrene (ABS) is a thermoplastic polymer widely used in several everyday life applications; moreover, it is also one of the most employed plastics in contemporary artworks and design objects. In this study, the chemical and thermal properties of an ABS-based polymer and its photo-degradation process were investigated through a multi-analytical approach based on thermal, mass spectrometric and spectroscopic techniques. LEGO building blocks were selected for studying the ABS properties.

Microscale mechanochemical characterization of drying oil films by in situ correlative Brillouin and Raman spectroscopy.

Correlative Brillouin and Raman microspectroscopy (BRaMS) is applied for the in situ monitoring of the chemical and physical changes of linseed oil during polymerization. The viscoelastic properties of the drying oil throughout the phase transition were determined by Brillouin light scattering (BLS) and joined to the Raman spectroscopic information about the chemical process responsible for the oil hardening. A comparative study was then performed on an oil mock-up containing ZnO, one of the most common white pigments used in cultural heritage.

Modelling the Interaction between Carboxylic Acids and Zinc Oxide: Insight into Degradation of ZnO Pigments.

Computational modelling applied to cultural heritage can assist the characterization of painting materials and help to understand their intrinsic and external degradation processes. The degradation of the widely employed zinc oxide (ZnO)-a white pigment mostly used in oil paints-leads to the formation of metal soaps, complexes of Zn ions and long-chain fatty acids coming from the degradation of the oil binder. Being a serious problem affecting the appearance and the structural integrity of many oil paintings, it is relevant to characterize the structure of these complexes and to understand the reaction pathways associated with this degradation process.

Unveiling the composition of historical plastics through non-invasive reflection FT-IR spectroscopy in the extended near- and mid-Infrared spectral range.

The present research exploits the strengths of external reflection FT-IR spectroscopy to non-invasively study heritage plastic objects through inspection, for the first time, of the wide spectral range including the near- and mid-IR (12500-350 cm). Unlike most of previous works on historical plastic objects, reflection-mode spectra were not corrected for the unfamiliar surface reflection profiles to the more recognizable absorption-like band shapes. This avoided data misinterpretation due to ill-suited Kramers Krönig correction when volume reflection is also present or when highly absorbing IR compounds generate Reststrahlen bands.

An integrated analytical study of crayons from the original art materials collection of the MUNCH museum in Oslo.

Among the artists' materials of the nineteenth century, pastel crayons merit scientific interest since their early commercial formulations are mostly unknown and, until now, have been considerably less studied with respect to other contemporary painting materials. In this framework, research herein reports the results of a comprehensive multi-analytical study of 44 pastel crayons of two recognized brands (LeFranc and Dr. F.

Single-sided NMR: a non-invasive diagnostic tool for monitoring swelling effects in paint films subjected to solvent cleaning.

During solvent cleaning of a painted surface, the control of solvent diffusion into the painting matrix is a primary concern for conservators. In this work, a comparative systematic study of solvent ingress and of the ensuing swelling phenomenon in paint films due to cleaning treatments was tackled using single-sided NMR. Specifically, the effects of a TAC aqueous solution (triammonium citrate in deionized water) applied in both free and gelled forms (by Klucel G) on acrylic emulsion and vinyl-based model paints were evaluated.

Revealing the Nature and Distribution of Metal Carboxylates in Jackson Pollock's Alchemy (1947) by Micro-Attenuated Total Reflection FT-IR Spectroscopic Imaging.

Protrusions, efflorescence, delamination, and opacity decreasing are severe degradation phenomena affecting oil paints with zinc oxide, one of the most common white pigments of the 20th century. Responsible for these dramatic alterations are the Zn carboxylates (also known as Zn soaps) originated by the interaction of the pigment and the fatty acids resulting from the hydrolysis of glycerides in the oil binding medium. Despite their widespread occurrence in paintings and the growing interest of the scientific community, the process of formation and evolution of Zn soaps is not yet fully understood.

Immunochemical Methods Applied to Art-Historical Materials: Identification and Localization of Proteins by ELISA and IFM.

Despite the large diffusion of natural organic substances in art-historical materials, their characterization presents many challenges due to the chemical complexity and instability with respect to degradation processes. Among natural products, proteins have been largely used in the past as binders but also as adhesives or additives in coating layers. Nevertheless, biological identification of proteins in art-historical objects is one of the most recent achievements obtained in heritage science thanks to the development of specifically tailored bio-analytical strategies.

Tracing the biological origin of animal glues used in paintings through mitochondrial DNA analysis.

We report the development of a suitable protocol for the identification of the biological origin of binding media on tiny samples from ancient paintings, by exploitation of the high specificity and high sensitivity offered by the state-of-the art DNA analysis. In particular, our aim was to molecularly characterize mitochondrial regions of the animal species traditionally employed for obtaining glues. The model has been developed using aged painting models and then tested to analyze the organic components in samples from the polychrome terracotta Madonna of Citerna by Donatello (1415-1420), where, by GC-MS and FTIR spectroscopy, animal glues and siccative oils were identified.

Non-invasive chemical and phase analysis of Roman bronze artefacts from Thamusida (Morocco).

A repertory of Roman military bronze equipment (1st- 3rd century AD) found at the archaeological site of Thamusida (Rabat, Morocco) was analysed by non-destructive X-ray fluorescence and time of flight neutron diffraction (ToF-ND). Most objects are made of leaded alloys, where copper is combined with tin and/or zinc and, in six cases, to arsenic as well. A mixed technology was employed, making a limited use of "pure" semi-finished materials if compared with the large utilization of recycled materials (brass and bronze).

Immunodetection of proteins in ancient paint media.

Diagnostic immunology is a powerful tool, widely used in clinical and biochemical laboratories for detecting molecules. In recent years, the technique has been adapted to materials sciences as a result of the extensive advances achieved in immunology. Today, many companies supply custom antibodies as well as new high-performance bioprobes for virtually any use.

The application of in situ mid-FTIR fibre-optic reflectance spectroscopy and GC-MS analysis to monitor and evaluate painting cleaning.

The development of non-invasive methodologies and portable instrumentation for in situ studies has been subject to great research and development in recent years in the field of conservation science. Despite such interest, very few reported studies employ these versatile techniques in the monitoring of cleaning treatments. This paper describes the application of mid-FTIR fibre-optic reflectance spectroscopy to monitor and evaluate the cleaning treatment of an oil painting using the chelating agent, triammonium citrate, a task undertaken in close collaboration with the painting conservator.

Proteomic strategies for the identification of proteinaceous binders in paintings.

The identification of proteinaceous components in paintings remains a challenging task for several reasons. In addition to the minute amount of sample available, complex and variable chemical composition of the paints themselves, possible simultaneous presence of several binders and contaminants, and degradation of the original materials due to aging and pollution are complicating factors. We proposed proteomic strategies for the identification of proteins in binders of paintings that can be adapted to overcome the requirements and difficulties presented by specific samples.

Combined crossed molecular beam and theoretical studies of the N(2D) + CH4 reaction and implications for atmospheric models of Titan.

The dynamics of the H-displacement channel in the reaction N((2)D) + CH(4) has been investigated by the crossed molecular beam (CMB) technique with mass spectrometric detection and time-of-flight (TOF) analysis at five different collision energies (from 22.2 up to 65.1 kJ/mol).

Quantum effects in the differential cross Ssctions for the insertion reaction N(2D) + H2.

The quantum (QM) scattering theory has been difficult to apply to the family of insertion reactions and the approximate quasiclassical trajectory (QCT) method or statistical calculations were mostly applied. In this Letter, we compare the experimental differential cross sections for the title insertion reaction with the results of QM and QCT calculations on an ab initio potential energy surface. The QM results reproduce well the crossed beam experiment, while a small, but significant, difference in the QCT ones points to quantum effects, possibly the occurrence of tunneling through the combined potential and centrifugal barrier.