Structural Insights into the Dehydration and Rehydration of Gypsum.

The formation and transformation of phases within the CaSO-HO system are crucial in natural and industrial processes. Despite intensive research, however, the mechanisms of gypsum's (CaSO·2HO) thermal dehydration and rehydration remain unclear. Here we investigated the crystallographic and textural relationship between parent and product phases during the dehydration and rehydration of gypsum single crystals using two-dimensional X-ray diffraction (2D-XRD), field emission scanning electron microscopy (FESEM), in situ and ex situ transmission electron microscopy (TEM), and selected area electron diffraction (SAED).

Unraveling the pathological biomineralization of monosodium urate crystals in gout patients.

Crystallization of monosodium urate monohydrate (MSU) leads to painful gouty arthritis. Despite extensive research it is still unknown how this pathological biomineralization occurs, which hampers its prevention. Here we show how inflammatory MSU crystals form after a non-inflammatory amorphous precursor (AMSU) that nucleates heterogeneously on collagen fibrils from damaged articular cartilage of gout patients.

Bio-Inspired Fluorescent Calcium Sulfate for the Conservation of Gypsum Plasterwork.

In this work, the potential of bio-inspired strategies for the synthesis of calcium sulfate (CaSO·nHO) materials for heritage conservation is explored. For this, a nonclassical multi-step crystallization mechanism to understand the effect of calcein- a fluorescent chelating agent with a high affinity for divalent cations- on the nucleation and growth of calcium sulfate phases is proposed. Moving from the nano- to the macro-scale, this strategy sets the basis for the design and production of fluorescent nano-bassanite (NB-C; CaSO·0.

Unveiling the secret of ancient Maya masons: Biomimetic lime plasters with plant extracts.

Ancient Maya produced some of the most durable lime plasters on Earth, yet how this was achieved remains a secret. Here, we show that ancient Maya plasters from Copan (Honduras) include organics and have a calcite cement with meso-to-nanostructural features matching those of calcite biominerals (e.g.

Silica-Functionalized Nanolimes for the Conservation of Stone Heritage.

The relatively recent development of nanolimes (i.e., alcoholic dispersions of Ca(OH) nanoparticles) has paved the way for new approaches to the conservation of important art works.

Direct evidence for metallic mercury causing photo-induced darkening of red cinnabar tempera paints.

Photo-induced darkening of red cinnabar (HgS) has attracted the interest of many researchers as it drastically impacts the visual perception of artworks. Darkening has commonly been related to metallic mercury (Hg) formation in the presence of chlorides. Based on the study of UV-aged cinnabar pigment and tempera paint we propose an alternative pathway for the blackening reaction of cinnabar, considering its semiconductor properties and pigment-binder interactions.

Synthesis of high surface area CaSO·0.5HO nanorods using calcium ethoxide as precursor.

We report a novel solvothermal route for the production of bassanite (CaSO·0.5HO) nanoparticles using amorphous Ca-ethoxide as a precursor. Bassanite nanorods, 120-200 nm in length, with the highest specific surface area reported so far (54 m g) and enhanced reactivity, are obtained at 78 °C and 1 atm.

Bacterial Diversity Evolution in Maya Plaster and Stone Following a Bio-Conservation Treatment.

To overcome the limitations of traditional conservation treatments used for protection and consolidation of stone and lime mortars and plasters, mostly based on polymers or alkoxysilanes, a novel treatment based on the activation of indigenous carbonatogenic bacteria has been recently proposed and applied both in the laboratory and . Despite very positive results, little is known regarding its effect on the evolution of the indigenous bacterial communities, specially under hot and humid tropical conditions where proliferation of microorganisms is favored, as it is the case of the Maya area. Here, we studied changes in bacterial diversity of severely degraded tuff stone and lime plaster at the archeological Maya site of Copan (Honduras) after treatment with the patented sterile M-3P nutritional solution.

pH-Dependent Adsorption Release of Doxorubicin on MamC-Biomimetic Magnetite Nanoparticles.

New biomimetic magnetite nanoparticles (hereafter BMNPs) with sizes larger than most common superparamagnetic nanoparticles were produced in the presence of the recombinant MamC protein from Magnetococcus marinus MC-1 and functionalized with doxorubicin (DOXO) intended as potential drug nanocarriers. Unlike inorganic magnetite nanoparticles, in BMNPs the MamC protein controls their size and morphology, providing them with magnetic properties consistent with a large magnetic moment per particle; moreover, it provides the nanoparticles with novel surface properties. BMNPs display the isoelectric point at pH 4.

Crystallization and Colloidal Stabilization of Ca(OH) in the Presence of Nopal Juice (Opuntia ficus indica): Implications in Architectural Heritage Conservation.

Hydrated lime (Ca(OH)) is a vernacular art and building material produced following slaking of CaO in water. If excess water is used, a slurry, called lime putty, forms, which has been the preferred craftsman selection for formulating lime mortars since Roman times. A variety of natural additives were traditionally added to the lime putty to improve its quality.

Protection and consolidation of stone heritage by self-inoculation with indigenous carbonatogenic bacterial communities.

Enhanced salt weathering resulting from global warming and increasing environmental pollution is endangering the survival of stone monuments and artworks. To mitigate the effects of these deleterious processes, numerous conservation treatments have been applied that, however, show limited efficacy. Here we present a novel, environmentally friendly, bacterial self-inoculation approach for the conservation of stone, based on the isolation of an indigenous community of carbonatogenic bacteria from salt damaged stone, followed by their culture and re-application back onto the same stone.