Glasses containing simultaneously iron and manganese have been widely used in medieval times to produce a wide range of colorations from green to purple. Technical recipes are, however, not known due to the lack of historical documents. A large panel of medieval-like glasses containing variable amounts of iron and manganese oxides has been produced under variable atmosphere (air, H-2, O-2) and at different melting temperatures (1200 degrees C, 1350 degrees C, and 1500 degrees C). Using optical absorption spectroscopy to probe the glass coloration, information has been derived on the interactions between Fe2+, Fe3+, Mn2+, and Mn3+ ions during the glass synthesis. An abacus relating temperature and the MnO to (MnO+FeO) ratio has been set up and used to deduce the melting temperatures of a set of historical glasses from the literature. The derived temperatures were, however, too high for medieval furnaces, quantitatively confirming the common knowledge that the synthesis atmosphere in the medieval furnaces had to be more reduced than pure air. The relationship between glass coloration and synthesis parameters, the extensive set of glasses studied in this work, quantitatively allowed to enlighten the effect of the so-called "glassmaker's soap" for the first time and the conditions to obtain an uncolored glass at any temperature.

This study investigates the synthesis, characterization, and functional properties of well-aligned zinc oxide (ZnO) nanowires (NWs) obtained by a two-step hydrothermal method. ZnO NWs were grown on silicon substrates precoated with a ZnO seed layer. The growth process was conducted at 90 °C for different durations (2, 3, and 4 h) to examine the time-dependent evolution of the nanowire properties. A comprehensive characterization of the ZnO NWs was performed using several analytical techniques. Scanning electron microscopy (SEM) revealed the morphological progression, specifically tracking changes in length and diameter as a function of the growth time. Ultraviolet (UV)-visible spectroscopy was employed to determine the optical band gap, while photoluminescence (PL) analysis provided insight into the concentration of structural defects and its evolution as a function of nanowire growth. The photocatalytic efficiency of the ZnO NWs was evaluated through the degradation of the organic dye methylene blue (MB) under UV light irradiation (365 nm). The kinetic of MB degradation was monitored for each growth time, with non-purgeable organic carbon (NPOC) analysis providing a detailed perspective on the photocatalytic activity over time. The antibacterial properties were tested against Pseudomonas putida, a Gram-negative bacterium, to determine the efficiency of the synthesized ZnO NWs as antimicrobial agents. The release of zinc ions (Zn2+), a key factor in the antibacterial mechanism, was quantified using inductively coupled plasma (ICP) analysis for each sample. By exploration of the relationship between the growth time, nanostructure morphology, and functional properties, this study provides insights into optimizing the synthesis of ZnO NWs for enhanced photocatalytic and antibacterial applications. These findings contribute to the development of advanced materials for environmental and biomedical applications.

This paper investigates the alteration of copper acetate (verdigris) and resinate green pigments widely used in oil paintings during the Middle Ages and Renaissance periods. These are bimetallic Cu(II) complexes. Their alteration consists in a color change of these bimetallic pigments from green into brown resulting in a darkening.By combining micro-analysis of both historical painting samples and analogue mock-ups this study elucidates the interactions between pigments and organic oily matrix and the chemical changes leading to the long-term degradation of copper acetate and resinate.Different analytical techniques were combined to characterize browning and identify degradation markers. The use of multimodal micro- spectroscopic techniques with a high lateral resolution (such as scanning electron microscopy, infrared micro spectroscopy, synchrotron photoluminescence, synchrotron micro-X-ray absorption near edge spectroscopy at the Cu K-edge) proved to be successful for the characterization of paint stratigraphy. The study shows the development of the pigment degradation from the surface to the inner painted layers, its facilitated propagation through defects (as cracks) and the influence of light and oxygen.The reproduced alteration in model samples fits with the ageing of masterpiece paintings. Finally, the browning mechanism is attributed to the formation of new copper complexes resulting from the ageing of organic binder and its interaction with copper bimetallic, without any detected structural modification of pigments in altered and non-altered areas.

Given the growing concern over antibiotic resistance, there is an urgent need to explore alternative antibacterial strategies. Metal oxide nanostructures have emerged as a promising option, and in particular, zinc oxide (ZnO) nanostructures have demonstrated strong antifungal and antibacterial properties. This study focuses on ZnO nanowires (ZnO NWs) and their potential as antibacterial agents against Pseudomonas putida, a Gram-negative bacterium. The objective is to investigate the antibacterial mechanisms and assess their efficiency. The unique shape of ZnO NWs, obtained through hydrothermal growth, may rupture bacterial cells and inhibit bacterial growth. In addition to their morphology, the release of Zn2+ ions from ZnO NWs may contribute to their antibacterial properties. These ions have the potential to disrupt the bacterial cell membrane, further impeding bacterial growth. Moreover, ZnO nanostructures exhibit excellent photocatalytic properties under UV light, enhancing their antibacterial effects. Overall, this study highlights the potential of hydrothermally synthesized ZnO NWs in inhibiting P. putida growth and provides valuable insights into their antibacterial mechanisms. The findings suggest that ZnO nanostructures have the potential to be effective antibacterial agents and could be utilized in various settings to fight microbial infections and maintain hygiene.

The Mn-bearing medieval stained-glass windows are affected by a browning phenomenon that could have a microbiological origin. This study investigates the direct and indirect impact of a model Mn-oxidizing and siderophore productive bacterial strain (Pseudomonas putida) on the alteration of medieval glass. For that, five model glasses with variable contents of Mn and Fe were altered during 1 week at 25degree celsius and pH 6.5 either in the presence of the siderophore desferrioxamine B (DFOB) at 50 mM or with the bacterial strain P. putida with or without external sources of iron. DFOB was shown to accelerate the dissolution of the Mn- and Fe -bearing glasses. By contrast, the presence of bacteria, had no apparent effect on glass dissolution, but led to the formation of a biofilm that was enriched in some elements of the glass, especially Si. The results also underlined the key -role of P of the glass as a nutrient for bacterial growth. Brown Mn oxides phases were only formed either when bacteria were incubated with Mn- and P -bearing glasses and after the production of the siderophore pyoverdine. Conversely, no browning was observed for the glass containing MnO and FeO with bacteria, which highlights that the absence of Fe plays a triggering role in the formation of manganese oxides.

Stained glass windows are a precious heritage to pass on to future generations. However, medieval stained glass windows are particularly altered due to their chemical composition and the effects of climatic (mainly water and temperature), environmental (pollution) and biological factors. In this review, we present the alteration patterns observed on ancient Si-K-Ca stained glass windows. To better understand their formation mechanisms and determine the alteration rates, different exposure campaigns to the current atmosphere in a position sheltered from rain or not and laboratory experiments in aqueous medium or in gaseous phase have been conducted. Either model glass or ancient stained glass windows were studied. Isotopic tracers (D, 18 O, 29 Si) have been used as they constitute a powerful tool to elucidate the involved processes and to measure their kinetics. Thanks to all of these data, an alteration scenario of medieval stained glass alteration is proposed. Besides, the extrapolation of kinetic data based on several hypotheses over seven centuries gives very consistent results compared to the ancient stained glass samples.

In order to explore the role of bacteria in the alteration of stained glass windows, and especially on the browning phenomenon, it is necessary to have an overview of the microbial inhabitants likely to be found on this kind of material. In this study, biological samples were collected on stained glass of different colours, both on site and stored in a conservation workshop. Cultivable bacterial communities were identified by 16S rDNA sequencing. Similarity values ranged from 99 to 100% to known bacteria. Sequence analysis showed different bacterial communities depending on the sampling site. The more represented genera were Arthrobacter, Micrococcus, Paenibacillus and Bacillus. Some of the identified bacteria are known for their weathering potential.

This work aims to investigate the role played by a model Mn-oxidizing bacterial strain and its exudates on the alteration of Mn-bearing potash-lime silicate glasses representative of medieval stained glass windows. Two model glasses, with or without manganese, were prepared and used for abiotic and Pseudomonas putida inoculated dissolution experiments. Results show that the presence of P. putida slows down the dissolution kinetics while changing the dissolution stoichiometry. In biotic experiments, the acidification of the solution at the beginning of the experiment favors the release of K. After a few days, a drop in Mn and P in solution is observed, retained by bacterial cells. Reciprocally, the amount of glass influences bacterial behavior. The more glass, the faster the bacterial population increases in size and produces siderophore. In the presence of the Mn-bearing glass, siderophore production is followed by the formation of brown phases, identified as Mn oxides.

The browning phenomenon is a pathology affecting Mn-bearing medieval stained-glass-windows in potash-limesilicate glass system. In order to unravel the potential implication of microorganisms in the appearance of this pathology, three model glasses respectively containing no MnO, 1 wt% and 2 wt% MnO were altered at circumneutral pH, with and without organic exudates (oxalic acid (OA) 1000 mu M and siderophore desferrioxamine B (DFOB) 50-1000 mu M) likely to be produced by bacteria and fungi. In the absence of exudates, the dissolution rates are inversely dependent on the Mn content of the glasses (0.8, 0.5 and 0.4 g m ? 2d-1 respectively for no MnO, 1 wt% and 2 wt% MnO glasses). In contact with exudates, an opposite trend is observed. The prevalent mechanisms are interpreted as a strong ligand-promoted dissolution for DFOB (dissolution rate increase up to 270%) and a dominant proton-promoted dissolution for OA (dissolution rate increase up to 60%). When DFOB and OA are added together, the effect of DFOB on the dissolution rate is prevailing, while OA effect is tangible on the stoichiometry of the dissolution of the alteration. These results suggest that an indirect biological activity could be involved in the mobilization of Mn from a Mn-bearing glass, thus playing a role in the appearance of the browning phenomenon.

Manganese is a chemical element used as a colourizer in glass industry since antiquity. Combined with iron, manganese often plays the role of a decolourizer leading to uncoloured glasses used to represent hands and faces in medieval stained glass windows. A series of medieval-like glasses has been synthesized in order to relate the colouration of glasses with the conditions of synthesis (temperature, atmosphere, glass composition). Optical absorption spectra in the UV-Vis-NIR range have been measured to follow and characterize the changes in colouration. For a given temperature, the addition of Mn in a Fe-rich glass composition implies a decrease of the concentration in Fe(2+)and an increase of the concentration in Fe3+ as compared to the Mn-free glass composition. The uncoloured glass composition is obtained for different contents of Mn when melting temperature varies. These results might help deciphering the complexity of colour making in ancient times.

Biosurfactants, surface-active agents produced by microorganisms, are increasingly studied for their potential use in soil remediation processes because they are more environmentally friendly than their chemically produced homologues. In this work, we report on the use of a crude biosurfactant produced by a bacterial consortium isolated from a PAHs-contaminated soil, compared with other (bio)surfactants (Tween80, Sodium dodecyl sulfate - SDS, rhamnolipids mix), to wash PAHs from a contaminated porous media. Assays were done using columns filled with sand or sand-clay mixtures (95:5) spiked with four model PAHs. The crude biosurfactant showed less adsorption to the [sand] and the [sand + clay] columns compared to Tween 80, SDS and the rhamnolipid mix. The biosurfactant showed the second best capacity to remove PAHs from the columns (as dissolved and particulate phases), both from [sand] and [sand + clay], after SDS when applied at lower concentrations than the other sufactants. The effluent concentrations of phenanthrene (PHE), pyrene (PYR) and benzo[a]pyrene (BAP) increased in the presence of the crude biosurfactant. Compared to the control experiment using only water, the global PAHs washed mass (amount of PAHs removed from the columns) increased between 9 and 1000 times for PHE and BAP in the [sand] column, and between 55 and 6000 times respectively for PHE and BAP in the [sand + clay] columns. Moreover, in the [sand + clay] columns, leaching of a part of the clays was observed in the SDS and the biosurfactant injections assays. This clay leaching resulted in higher PAHs removal, due not to desorption but rather to particulate transport. In the context of washing PAH-contaminated soils in biopiles or subsurface remediation, our results could help in sizing the remediation approach using an environmental friendly biosurfactant, before a pump-and-treat process.

SYNROC is a ceramic composed of several titanate phases designed to immobilize radioactive waste. CaTiO 3 perovskite is one of its major components and many studies demonstrated that, in CaTiO 3 , Ca can be substituted by trivalent Rare Earth Elements (REE) thanks to their close ionic radii. In a study on a Nd-doped CaSnO 3 perovskite a new substitution mechanism was revealed Nd substitutes the Ca on the Ca site and the excess of charge is compensated by the migration of Ca on the Sn site (Ca 1-2x Ln 2x )(Sn 1-x Ca x )O 3 [1]. In this study, we verify that this mechanism of incorporation can be applied on three REE (Ln = La, Pr and Nd) in the structure of CaTiO 3 and we also investigate their durability.

The formation of iron- and/or manganese-rich dark patinas on sandstones is a common natural phenomenon that occurs also on building stones. Lunéville château, in eastern France, presents such patinas that developed either under natural conditions (rain and time) or after an accidental fire and exposure to significant amounts of water as part of attempts to extinguish the fire. The present study aimed at characterizing both types of patinas in an effort to determine their formation mechanisms and Mn sources. In both cases, Mn required for patina formation likely derives from the reductive dissolution of Mn-rich minerals present in pristine sandstones, as suggested by the contrasting mineralogy and chemistry of Mn-rich phases present in the bulk and in the patina of a given building block. Reduced Mn species then migrate to the exposed surface of building blocks where they are re-oxidized via undetermined processes. Patinas developing “naturally” over time result from the alternation of wetting-reducing and drying-oxidizing cycles and appear to be composed of birnessite. Patinas formed after the 2003 fire result from this single accidental event and form a much thinner, heterogeneous, and discontinuous layer of poorly crystalline lithiophorite at the sandstone surface (∼ 0–150 µm compared to ∼ 300–600 µm for “natural” patinas). The lack of Mn-rich patinas on areas of Lunéville château is likely related to the lower Mn content of pristine sandstone blocks.