More recently, the biological colonization of stone heritage and consequently its biodeterioration has become the focus of numerous studies. Among all microorganisms, fungi are considered to be one of the most important colonizers and biodegraders on stone materials. This is why the development of new antifungal materials requires immediate action. ZnMgO nanoparticles (NPs) have several exciting applications in different areas, highlighting as an efficient antimicrobial agent for medical application. In this research, the application of Zn-doped MgO (Mg1–x Zn x O, x = 0.096) NPs obtained by sol–gel method as antifungal coatings on dolomitic and calcitic stones has been explored as a means to develop effective protective coatings for stone heritage. Moreover, the photocatalytic and antifungal activity of Mg1–x Zn x O NPs were comparatively studied with single ZnO and MgO NPs. Thus, compared to the MgO and ZnO nanomaterials, the Mg1–x Zn x O NPs exhibited an enhanced photocatalytic activity. After UV irradiation for 60 min, 87% methylene blue was degraded over Zn-doped MgO NPs, whereas only 58% and 38% of MB was degraded over ZnO and MgO NPs, respectively. These nanoparticles also displayed a better antifungal activity than that of single pure MgO or ZnO NPs, inhibiting the growth of fungi Aspergillus niger, Penicillium oxalicum, Paraconiothyrium sp., and Pestalotiopsis maculans, which are especially active in the bioweathering of stone. The improved photocatalytic and antifungal properties detected in the Mg1–x Zn x O NPs was attributed to the formation of crystal defects by the incorporation of Zn into MgO. The application of the MgO- and Zn-doped MgO NPs as protective coatings on calcareous stones showed important antifungal properties, inhibiting successfully the epilithic and endolithic colonization of A. niger and P. oxalicum in both lithotypes, and indicating a greater antifungal effectiveness on Zn-doped MgO NPs. The use of Zn-doped MgO NPs may thus represent a highly efficient antifungal protection for calcareous stone heritage.

In recent times, nanomaterials have been applied in the construction and maintenance of the worldÅLs cultural heritage with the aim of improving the consolidation and protection treatments of damaged stone. These nanomaterials include important advantages that could solve many problems found in the traditional interventions. The present paper aims to carry out a review of the state of art on the application of nanotechnology to the conservation and restoration of the stony cultural heritage. We highlight the different types of nanoparticles currently used to produce conservation treatments with enhanced material properties and novel functionalities.

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Opportunities for the synthesis of ultrafine spherical particles with uniformly distributed components and phases are of special importance when materials for photonic application are considered. In this study, the nanophase, spherical, luminescent polycrystalline Gd 2 O 3 :Eu and YAG:Ce particles were synthesized from aerosols of the corresponding nitrate solutions ultrasonically generated with frequencies of 1.7 MHz and 800 kHz, respectively. Detailed phase and structural analysis, compositional homogeneity, and particle morphology were determined in accordance to X-ray diffraction ͑XRD͒, scanning electron microscopy ͑SEM͒, and energy dispersive X-ray spectroscopy ͑EDS͒. Quantitative SEM/EDS analysis indicated high material purity and compositional homogeneity. The phase development and structural changes imply nanocrystalline inner structure ͑crystallites below 60 nm after thermal treating͒, which influences luminescence behavior. Luminescence measurements indicate that both the radioluminescence and thermoluminescence emission spectra of the Gd 2 O 3 :Eu are totally dominated by the line emission characteristic of the Eu, fully substituted onto host lattice sites. By contrast, the cerium dopants in YAG display only very weak Ce luminescence after annealing, but there are broad emission bands characteristic of host lattice defect sites. The spectra are clearly altered by heat treatments and the thermoluminescence indicates a range of independent defect emission sites.

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W and W V alloys reinforced with La 2 O 3 particles have been produced by MA and subsequent HIP at 1573 K and 195 MPa. The microstructure of the consolidated alloys has been characterized by scanning electron microscopy, energy dispersive spectroscopy analyses and X ray diffraction. The mechanical properties were studied by nanoindentation measurements. The results show that practically full dense billets of W V, W V La 2 O 3 and W La 2 O 3 alloys can be produced. The microstructure analysis has shown that islands of V are present in W V and W V 1La 2 O 3 alloys. In W 1La 2 O 3 islands of La 2 O 3 are also pres ent. The nanohardness of the W matrix increases with the addition of V, while decreases with the addi tion of La 2 O 3 .

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