Multianalytical approach to the analysis of English polychromed alabaster sculptures: μRaman, μEDXRF,and FTIR spectroscopies

A complete study of several English polychromed alabaster sculptures is presented. The support, pigment, and binders were characterised by combining μEDXRF, μRaman, and FTIR spectroscopies. Among the pigments, minium, vermilion, lead white, carbon black, red iron oxide, and a degraded green copper pigment were determined, together with gold leaf. The presence of the rare mineral moolooite (copper oxalate) was also found as a degradation product in the green areas, where weddellite (calcium oxalate dihydrate) was also determined. These facts, together with degradation of the green copper pigment, suggest microbiological degradation of the original materials. Remains of glue and a varnish were also determined by FTIR spectroscopy and principal-components analysis (PCA) of the spectra. Finally, PCA analysis was carried out to confirm whether the pieces came from the same quarry.     

How the central torsion angle affects the rates of nonradiative decay in some geometrically restricted p-quaterphenyls

A small series of p-quaterphenyl derivatives has been prepared in which the dihedral angle (phi) for the two central rings is constrained by dialkoxy spacers of varying length. The photophysical properties of these compounds remain comparable, but there is a clear correlation between the rate constants for nonradiative decay of both singlet and triplet excited states and phi in fluid solution. The rates tend toward a minimum as phi approaches 90 degrees . These effects are attributed to the general phenomenon of extended delocalization and can be traced to a combination of changes in the Huang-Rhys factor and the electron-vibrational coupling matrix element, both relating to displacement of the relevant potential energy surfaces and to the medium-frequency vibronic mode coupled to decay. The latter effect arises because of different levels of conjugation in the ground-state molecule. Such findings might have important implications for the design of improved light-emitting diodes. A similar angle dependence is noted for the yield of the pi-radical cation formed on photoionization in a polar solvent, but here, the effect is due to variations in the respective energy gaps between the relevant excited states.     

In‐situ spectroscopic assessment of the conservation state of building materials from a Palace house affected by infiltration water

The built Heritage constantly suffers different deterioration processes caused by the action of external agents, being one of the main consequences of the formation of soluble salts. These salts appear as efflorescences or subefflorescences that by hydration and dehydration cycles and/or dissolution processes producing crystallization of salts within the pores may promote internal fractures and material loss. The assessment of building material conservation on a 15^th century Palace house, located close to the Urola river (Azpeitia, Basque Country, North of Spain), has been performed by in‐situ characterization of pathologies on sandstone, mortar and limestone affected by infiltration waters. Portable Raman and X‐ray fluorescence spectrometers have been used to characterize the bulk materials as well as the salts present along the different walls of the Palace. The in‐situ analysis by those portable equipments has been complemented with laboratory measurements on selected samples, taken close to the spots analysed by the portable instruments. Different carbonates (natrite, termonatrite, natron, calcite and gaylussite), oxides (hematite, limonite and rutile), feldspar (orthoclase) and silicates (quartz) have been identified as original compounds. Furthermore, nitrates (niter, nitrocalcite and nitratine) and sulphates (gypsum and thenardite) have been found as decaying compounds permitting to establish the degradation processes of the attack produced by the infiltration waters on the different building materials. Moreover, the study revealed that certain materials used in a previous restoration produced new degradation processes, evidencing the importance of a proper selection of the materials to be used in the interventions. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation and Characterization of Mg‐Zr Mixed Oxide Aerogels and Their Application as Aldol Condensation Catalysts

A series of Mg‐Zr mixed oxides with different nominal Mg/ (Mg+Zr) atomic ratios, namely 0, 0.1, 0.2, 0.4, 0.85, and 1, is prepared by alcogel methodology and fundamental insights into the phases obtained and resulting active sites are studied. Characterization is performed by X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy, N₂ adsorption–desorption isotherms, and thermal and chemical analysis. Cubic Mg_xZr_1?xO_2?x solid solution, which results from the dissolution of Mg²⁺ cations within the cubic ZrO₂ structure, is the main phase detected for the solids with theoretical Mg/ (Mg+Zr) atomic ratio ≤0.4. In contrast, the cubic periclase (c‐MgO) phase derived from hydroxynitrates or hydroxy precursors predominates in the solid with Mg/(Mg+Zr)=0.85. c‐MgO is also incipiently detected in samples with Mg/(Mg+Zr)=0.2 and 0.4, but in these solids the c‐MgO phase mostly arises from the segregation of Mg atoms out of the alcogel‐derived c‐Mg_xZr_1?xO_2?x phase during the calcination process, and therefore the species c‐MgO and c‐Mg_xZr_1?xO_2?x are in close contact. Regarding the intrinsic activity in furfural–acetone aldol condensation in the aqueous phase, these Mg? O? Zr sites located at the interface between c‐Mg_xZr_1?xO_2?x and segregated c‐MgO display a much larger intrinsic activity than the other noninterface sites that are present in these catalysts: Mg? O? Mg sites on c‐MgO and Mg? O? Zr sites on c‐Mg_xZr_1?xO_2?x. The very active Mg? O? Zr sites rapidly deactivate in the furfural–acetone condensation due to the leaching of active phases, deposition of heavy hydrocarbonaceous compounds, and hydration of the c‐MgO phase. Nonetheless, these Mg‐Zr materials with very high specific surface areas would be suitable solid catalysts for other relevant reactions catalyzed by strong basic sites in nonaqueous environments.     

Ultrasonic‐assisted derivatization of estrogenic compounds in a cup horn booster and determination by GC‐MS

Cup horn boosters are miniaturized ultrasound baths that maximize efficiency and precision. The optimization of an ultrasonic‐assisted derivatization step by means of a cup horn booster and the determination of estrone, 17β‐estradiol, estriol, 17α‐ethynyl estradiol and mestranol was developed by GC‐MS. Different derivatization reagents and solvents were studied for maximizing the di‐derivatization of 17α‐ethynyl estradiol under ultrasound energy. Only N,O‐bis(trimethylsilyl)trifluoroacetamide with 1% of trimethylchlorosilane in pyridine gave satisfactory results and this mixture was further used in the optimization of the ultrasound assisted derivatization. The experiment designs included sonication time (1–10 min), sonication power (20–80%), sonication cycles (1–9), derivatization reagent volume (25–125 μL) and solvent volume (25–125 μL). Once the optimum conditions were fixed, the effect of organic matter and the frequency of the water bath change were studied. Finally, the validation of the analytical method was carried out using spiked natural and synthetic waters. Recoveries (natural (138–70%) and synthetic (112–89%)), the LODs (0.35–1.66 ng/L), and LOQs (1.16–5.52 ng/L) and the precision (0.2–5.3%) of the method were studied. This is the first work in the literature where a cup horn booster is used with the aim of minimizing derivatization time during the determination of estrogenic compounds.     

Raman spectroscopy assisted with XRF and chemical simulation to assess the synergic impacts of guardrails and traffic pollutants on urban soils

Urban soils are potential reservoirs of toxic metals as a consequence of traffic emissions. Sources like brake linings, tyres, road pavement, exhaust fumes, guardrail, traffic signals and other galvanised steel structures are used in a large variety of external constructions in the modern urban areas. Their beneficial properties from a corrosion and oxidation perspective are well‐known but less is known about their contribution to the environmental fate of corrosion‐induced released zinc. In this work, the impact of guardrails and other traffic pollutants on urban soils has been studied by means of Raman spectroscopy (molecular speciation) and thermodynamic speciation to understand the mechanisms of metal release and uptake by the soils. Hydrozincite, Zn₅(CO₃)₂(OH)₆, was identified by means of Raman spectroscopy as the degradation compound of the galvanised zinc layer from guardrails which leads to the formation of soluble zinc, by acidic attack of the urban atmosphere, that drops and accumulate (zinc nitrate was identified) in soils. This fact shows the environmental risk of zinc release from the guardrails because zinc nitrate can be easily mobilised by water runoff, affecting the surrounding areas or groundwater. Other traffic pollutant that reaches guardrail and soil by atmospheric deposition, such as barium, was also identified in soil as well as in the guardrail in its carbonate form, BaCO₃. Because of its low solubility, barium will accumulate in urban soils. Copyright © 2012 John Wiley & Sons, Ltd.     

Holes and Ledges Created by Multilayer Assembly on Polyelectrolyte Brushes: A Novel Route for the Three‐Dimensional Nanoscale Design of Surfaces

The layer‐by‐layer (LBL) assembly of poly(diallyldimethylammonium chloride) and poly(sodium styrene sulfonate) on poly(sulfo propyl methacrylate) brushes resulted in films with nanometer‐ and micrometer‐sized holes and ledges, observed by atomic force microscopy and scanning electron microscopy. Polyelectrolyte assembly was followed by the quartz microbalance technique. The formation of ledges and holes is explained by the interaction of the brush polymers with the incoming polyelectrolytes during the LBL assembly, inducing a spatially localized and self‐organized accumulation of the assembled polymers.

     

Engineering multifunctional metal/protein hybrid nanomaterials as tools for therapeutic intervention and high-sensitivity detection

Protein-based hybrid nanomaterials have recently emerged as promising platforms to fabricate tailored multifunctional biologics for biotechnological and biomedical applications. This work shows a simple, modular, and versatile strategy to design custom protein hybrid nanomaterials. This approach combines for the first time the engineering of a therapeutic protein module with the engineering of a nanomaterial-stabilizing module within the same molecule, resulting in a multifunctional hybrid nanocomposite unachievable through conventional material synthesis methodologies. As the first proof of concept, a multifunctional system was designed ad hoc for the therapeutic intervention and monitoring of myocardial fibrosis. This hybrid nanomaterial combines a designed Hsp90 inhibitory domain and a metal nanocluster stabilizing module resulting in a biologic drug labelled with a metal nanocluster. The engineered nanomaterial actively reduced myocardial fibrosis and heart hypertrophy in an animal model of cardiac remodeling. In addition to the therapeutic effect, the metal nanocluster allowed for in vitro, ex vivo, and in vivo detection and imaging of the fibrotic disease under study. This study evidences the potential of combining protein engineering and protein-directed nanomaterial engineering approaches to design custom nanomaterials as theranostic tools, opening up unexplored routes to date for the next generation of advanced nanomaterials in medicine.

Engineering protein-based hybrids by combining protein engineering and nanotechnology: a protein-nanocluster hybrid for theranostic use in myocardial fibrosis shows the potential to create tailored multifunctional biologics for biomedicine.