High energy consumption in the nervous system requires a continuous supply of O2. This role is assisted by proteins from the globin super-family in the nerve cells of invertebrates, where 'nerve hemoglobins' (nHbs) are mainly present at mM concentrations and exhibit oxygen affinities comparable to those of vertebrate myoglobins. To gain insight into the structural bases of this function, we report the crystal structure of nHb from the Atlantic surf clam Spisula solidissima (SsHb), previously suggested to display a bis-histidyl hexa-coordinated heme in the deoxy state, high O2 affinity, and ligand binding cooperativity when assayed in situ. The crystallized protein forms a dimer through packing of a 4-helix bundle involving helices E and F of each subunit. The SsHb 'classic' globin fold displays bis-histidyl (His71(E7) and His103(F8)) hexa-coordination of the heme-Fe atom, with structural and dynamics variations found in the inter-helix hinge regions. Molecular Dynamics simulations of both monomeric and dimeric species in the bis-histidyl hexa-coordinated, deoxy penta-coordinated, and O2-bound hexa-coordinated states reveal distinct structural rearrangements at the interface between subunits in the dimer; these would affect the magnitude of the conformational fluctuations observed between monomer and dimer, and the topology of cavities within the protein matrix and at the interface. These results point to a distal site opening mechanism allowing access of the exogenous ligand to the heme and cast hypotheses on the dimer interface structural and dynamic properties that may support ligand binding cooperativity in dimeric SsHb.

Micro-Raman spectroscopy was employed for the analysis of samples collected from the shelters Campo Cerda 1, Angostura Blanca and Campo Moncada 1 located in Piedra Parada valley, Chubut province, Argentinian Patagonia. Different coloured layers, degradation products and rock supports were analysed. Haematite (alpha-Fe2O3), goethite (alpha-FeOOH), green earth and gypsum (CaSO4 center dot 2H(2)O) were responsible for the main colouration of the pigmented layers together with other components. Gypsum, Ca-oxalates and calcite were the major degradation materials affecting the rock paintings and the rock support. Different types of silicates, apatite [Ca-5(PO4)(3)(F,Cl,OH)] and goethite were positively characterized in the rock support. Point analysis and micro-Raman mappings contributed towards a better understanding of the materials and layer sequencing of the samples extracted.

A collection of glass beads found in Lumbu (Mbanza Kongo, Angola) were analyzed by means of a multi-analytical minimally invasive methodology, which included handheld X-ray fluorescence (hXRF), variable pressure scanning electron microscope coupled with energy dispersive X-ray spectrometry (VP-SEM-EDS), micro-Raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Trace element analysis, and rare earth element pattern analysis in particular, was found to be essential to establish the provenance of the European trade beads in this study. The glass beads from types 30, 31, 32, 36, 38, 39, 40, 41, 42, 43 and 45 were found to have been produced in Venice, and the glass beads from types 26 and 28 have been assigned to the Bohemian glass industry. While determining the provenance of each glass artefact was a major goal of this study, the process of glass coloring and opacification was also studied in an attempt to establish the technology employed in the production of these artefacts. Chemical data indicate that cobalt and copper were used to produce blue hues, while a combination of copper and iron ions was used to produce green glass. Black colored glass was obtained by the combined use of iron and manganese ions, whereas the iron-sulfur chromophore was used to impart a distinct amber hue to the glass. Red was produced using trace amounts of metallic gold particles (ruby red glass) and metallic copper nano-particles or cuprous oxide (brownish-red glass). Lead arsenates, calcium phosphate, and cassiterite were used as opacifying agents. The use of both morphological and chemical analysis enabled the identification of distinct European production centers, allowing a glimpse into the consumption patterns and economic interactions in place between Europe and West-Central Africa throughout the 17th-19th centuries.

Identifying the manufacturer of historical wall tiles is often based on visual inspection by an expert. This is a subjective and time-consuming approach, as it can only be performed on sight by few experts. In this work, it is evaluated whether Raman and X-ray fluorescence (XRF) spectroscopy can create a chemical fingerprint to discriminate the tile manufacturers based on their provenance. Using both analytical techniques and combining this with chemometrical analysis, different historical Belgian tile manufacturers are characterized. We were successful in discriminating the brown from the white glazes, as well as for discriminating most Belgian tile manufacturers based on their origin. For the latter, only the results of the white glazes were used. The results show that both Raman and XRF parameters are important markers, which is underlining the significance of their combined use and opens perspectives for their non-destructive use to distinguish the tile manufacturers, in situ.

Aims: Structural and functional characterization of the globin-coupled sensors (GCSs) from Azotobacter vinelandii (AvGReg) and Bordetella pertussis (BpeGReg). Results: Ultraviolet/visible and resonance Raman spectroscopies confirm the presence in AvGReg and BpeGReg of a globin domain capable of reversible gaseous ligand binding. In AvGReg, an influence of the transmitter domain on the heme proximal region of the globin domain can be seen, and k'CO is higher than for other GCSs. The O2 binding kinetics suggests the presence of an open and a closed conformation. As for BpeGReg, the fully oxygenated AvGReg show a very high diguanylate cyclase activity. The carbon monoxide rebinding to BpeGReg indicates that intra- and intermolecular interactions influence the ligand binding. The globin domains of both proteins (AvGReg globin domain and BpeGRegGb with cysteines (Cys16, 45, 114, 154) mutated to serines [BpeGReg-Gb*]) share the same GCS fold, a similar proximal but a different distal side structure. They homodimerize through a G-H helical bundle as in other GCSs. However, BpeGReg-Gb* shows also a second dimerization mode. Innovation: This article extends our knowledge on the GCS proteins and contributes to a better understanding of the GCSs role in the formation of bacterial biofilms. Conclusions:AvGReg and BpeGReg conform to the GCS family, share a similar overall structure, but they have different properties in terms of the ligand binding. In particular, AvGReg shows an open and a closed conformation that in the latter form will very tightly bind oxygen. BpeGReg has only one closed conformation. In both proteins, it is the fully oxygenated GCS form that catalyzes the production of the second messenger.

.The Archaeological Collection of Ghent University Museum hosts one of the most remarkable cork models representing the Pantheon of Rome, made by the master Antonio Chichi (1743-1816). Ghent University started a restoration campaign dedicated to the cork masterpiece, which has great artistic value. Next to macroscopic analysis, an extensive physicochemical campaign was organised in order to study and document the composition and the preservation state of the polychromic layers of Chichi's masterpiece. Portable and micro-Raman spectroscopy revealed the presence of materials such as carbon-based pigments, lead white, vermilion, chalk, gypsum, bassanite, Prussian blue and haematite on the exterior and interior of the cork model. A tin-containing layer was characterized on the exterior of the model. XRF instruments were employed to better understand the overall elemental composition of the model's polychromic layers, positively identifying Pb, Sn, Zn, Ca, Hg, Fe at the exterior surface. Stratigraphic analysis was performed, with both analytical techniques, when possible. The detailed information provided by archaeology, art history and applied sciences on the cork model of the Pantheon, will help the conservators to better understand and restore the Pantheon model which will be exhibited in the new museum of Ghent University.

Pigments and colourants are materials that have an enormous impact on how artworks are appreciated. Therefore, it is no surprise that since the first applications of Raman spectroscopy in art analysis, the study of this group of materials has gained special attention. Whereas the first applications often involved the identification of (mostly inorganic) pigments, the field has broadened towards the analysis of organic materials, such as synthetic pigments. Moreover, the study of dyes has gained from the developments in surface-enhanced Raman spectroscopy (SERS). Moreover, recently micro-spatially offset Raman spectroscopy (micro-SORS) was developed as a promising technique to study layered structures, such as paint layers.

An extensive in situ Raman spectroscopic campaign was performed on archaeological sites in three different provinces in Patagonia, Argentina (Neuquen, Rio Negro and Chubut). 16 open air shelters located in different environments (forests, ecotones, steppes) were investigated and interpreted in terms of pigments used and the identification of substrata. Special attention was given to the alteration products and accretions that were found on the rock art paintings of the shelters and on the surface of the rock walls, as they can affect and damage this magnificent works of art. Haematite (alpha-Fe2O3) was the main chromophore that was found on the red paintings of the most of the shelters studied. The green earth glauconite, was identified only in one case, by using a red (785 nm) and a green laser (532 nm). Other minerals and silicates were found on the coloured areas but also on the rock support. Calcite (CaCO3) and gypsum (CaSO4 center dot 2H(2)O) crystallization was identified on the paintings, crusts and rock surfaces, in combination or alone, and are associated with weathering. In some cases the shelters were so severely degraded that no Raman signal of pigments and/or other components could be retrieved. Calcium oxalates were also detected in several figures and motifs in different shelters. (C) 2018 Elsevier B.V. All rights reserved.

Archaeometry is the research area on the edge between humanities and natural sciences: it uses and optimises methods from chemistry, spectroscopy, physics, biology, etc. to help answering research questions from humanities. In general, these objects are investigated for several reasons. Besides the fundamental interest to know about the materials that were used in the past, the study of artefacts can support their preservation, either by helping to select optimal storage or display conditions, either by investigating decay pathways and suggesting solutions. Other reasons for art analysis include provenance studies, dating the artefact or identifying forgeries. Since several years, Raman spectroscopy is increasingly applied for the investigation of objects of art or archaeology. The technique is well-appreciated for the limited (or even absent) sample preparation, the relative straightforward interpretation of the spectra (by fingerprinting - comparing them against a database of reference pigments) and its speed of analysis. Moreover, the small spectral footprint - allowing to record a molecular spectrum of particles down to 1 mu m, the typical size of pigment grains - is certainly a positive property of the technique. Raman spectroscopy can be considered as rather versatile, as inorganic as well as organic materials can be studied, and as the technique can gather information on crystalline as well as on non-crystalline phases. As a consequence, Raman spectroscopy can be used to study antique objects and twentieth-century synthetic (organic) materials - illustrating the wide range of applications. Finally, the technique is as non-destructive, provided the laser power is kept sufficiently low not to damage the artwork. In literature, the terms "non-invasive" and "non-destructive" are used, where the first term means that no sampling is involved, and the latter term indicates that no sample is taken or that during analysis the sample is not consumed (destroyed) and remains available for further analysis.

The combined use of handheld energy-dispersive X-ray fluorescence spectrometry, Raman spectroscopy, and micro-energy-dispersive X-ray fluorescence spectrometry permitted the characterization of Roman glass tesserae excavation from the Coriglia (Italy) archeological site. Analyses of ten different glass colors were conducted as spot analyses on intact samples and as both spot analyses and line scans on select cross-sectioned samples. The elemental and molecular information gained from these spectral measurements allowed for the qualitative chemical characterization of the bulk glass, decolorants, opacifiers, and coloring agents. The use of an antimony opacifier in many of the samples supports the late Imperial phasing as determined through numismatic, fresco, ceramics, and architectural evidence. And dealinization of the exterior glass layers caused by the burial environment was confirmed.

Portable Raman spectroscopy is applied for the first time on rock art paintings from hunter‐gatherers in three different provinces in Patagonia, Argentina (Neuquén, Río Negro and Chubut). Selected archaeological sites were examined, revealing the local ‘palette’ of the native population and, if possible, the technology used. Moreover, alteration products were investigated to obtain valuable information for a better conservation and preservation of these magnificent rock art paintings. During a single research campaign, 16 shelters and one cave were investigated, which makes this study as one of the most condensed expeditions on measuring rock art paintings. Here, we evaluate the use of our portable Raman instrument to analyse rock art paintings under extreme conditions in Patagonia, Argentina. Several improvements are proposed to maximize the quality of the research output in such condensed expeditions. Copyright © 2017 John Wiley & Sons, Ltd.

Microspatially offset Raman spectroscopy (micro-SORS) has been proposed as a valuable approach to sample molecular information from layers that are covered by a turbid (nontransparent) layer. However, when large magnifications are involved, the approach is not straightforward, as spatial constraints exist to position the laser beam and the objective lens with the external beam delivery or, with internal beam delivery, the maximum spatial offset achievable is restricted. To overcome these limitations, we propose here a prototype of a new micro-SORS sensor, which uses bare glass fibers to transfer the laser radiation to the sample and to collect the Raman signal from a spatially offset zone to the Raman spectrometer. The concept also renders itself amenable to remote delivery and to the miniaturization of the probe head which could be beneficial for special applications, e.g., where access to sample areas is restricted. The basic applicability of this approach was demonstrated by studying several layered structure systems. Apart from proving the feasibility of the technique, also, practical aspects of the use of the prototype sensor are discussed.

Defocusing micro-SORS mapping allows studying the pigment distribution and stratigraphy in painted artwork.

In the framework of the inter‐disciplinary KongoKing project, a set of beads from archaeological excavations in the Democratic Republic of the Congo was analysed by means of a minimally invasive, multi‐analytical approach based on micro‐Raman spectroscopy. The full characterization of the materials, including glassy network, opacifiers and colorizers, was achieved thanks to the combination of data from handheld X‐ray fluorescence, variable pressure scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometry, micro‐Fourier transform infrared spectroscopy and pyrolysis coupled to gas chromatography and mass spectrometry. The obtained chemical information was used to fill the existing gap in the chemical study of beads from Western Central Africa. The cobalt‐rich blue beads were found to be of Central European origin, while the copper‐rich turquoise beads were manufactured using distinct copper sources. Cadmium yellow and cadmium red are the colourants responsible for the bright colours of bead types 10 and 12, respectively. The type 12 beads were found to be composed of glass covered with a waxy layer tentatively identified as Japan wax. Prosser‐moulded bead type 9 was coloured by means of a chrome–tin pigment, while a combination of Mn and Fe is responsible for the black colour of the type 47 beads. Cuprite is most likely responsible for the red hue of glass layers from type 14. The dark palm green exterior of the type 17 bead was produced by using a combination of Cu and Fe compounds; iron was the only chromophore detected in the Indian red decoration. Copyright © 2017 John Wiley & Sons, Ltd.

This review is to be considered part of the development of the MEMORI dosimeter, to evaluate the impact of climate (relative humidity, temperature, illumination, etc., including volatile organic compounds) on moveable objects. In the framework of the MEMORI project, Ghent University was given the task to assess pigment degradation upon acetic acid exposure, and to collect information on pigments’ stability. Moreover, to obtain a wider knowledge on the stability of common pigments, the effect of a variety of parameters was reviewed from literature. Discolouration and degradation of pigments significantly alter the legibility of polychrome works of art, so that the development of monitoring methods to ensure the preservation of cultural heritage objects is of primary importance.