Abstract: Results on analysis of prehistoric pigments from excavations and pigments on coloured child bones from North Patagonia, Argentina, are reported. To analyze their composition we used two micro-analytical techniques: micro- Raman spectrometry (MRS) and scanning electron microscopy coupled with X-ray micro-analysis (SEM/EDX). Most investigated excavated pigments show red or yellow ochres consistent with reddish or yellow minerals, such as á- and ã-goethite, haematite, erdite, haapalaite and jarosite. Raman spectra show also evidence of calcium oxalate monohydrate and calcite indicating lichen activity. Pigments covering human bones were identified as hematite and magnetite. This study allows us to infer that pigments found in excavation were employed for burial ceremonies, even though distances between excavated pigment archaeological site and buried remains are quite far, more than 50 km in a straight line.

Abstract: This work shows the benefits of characterizing historic paintings via compositional and microtextural data from micro-X-ray diffraction (μ-XRD) combined with molecular information acquired with Raman microscopy (RM) along depth profiles in paint stratigraphies. The novel approach was applied to identify inorganic and organic components from paintings placed at the 14th century Islamic UniversityMadrasah Yusufiyyain Granada (Spain), the only Islamic University still standing from the time of Al-Andalus (Islamic Spain). The use of μ-XRD to obtain quantitative microtextural information of crystalline phases provided by two-dimensional diffraction patterns to recognize pigments nature and manufacture, and decay processes in complex paint cross sections, has not been reported yet. A simple Nasrid (14th century) palette made of gypsum, vermilion, and azurite mixed with glue was identified in polychromed stuccos. Here also a Christian intervention was found via the use of smalt, barite, hematite, Brunswick green and gold; oil was the binding media employed. On mural paintings and wood ceilings, more complex palettes dated to the 19th century were found, made of gypsum, anhydrite, barite, dolomite, calcite, lead white, hematite, minium, synthetic ultramarine blue, and black carbon. The identified binders were glue, egg yolk, and oil.

Abstract: Porous limestone and mortar are able to absorb large quantities of water. This phenomenon will accelerate the deterioration of the material. In such cases, the material might be treated with a hydrophobic product, which creates a superficial layer that hampers the penetration of water. In order to decide if such a treatment should be applied or not, the water absorbing behaviour of the material should be measured. With the same measuring technique the efficiency of the hydrophobic barrier can be evaluated. Moreover, it allows the monitoring of such barriers as a function of time. At the same time, the water absorption of porous stone material is an indication of the degree of deterioration and its sensitivity to future deterioration. Up to now, two different measuring techniques exist, but one can only be used in laboratory and the other, which can be operated in laboratory as well as in situ, is not always reliable for in situ analyses. This article proposes an alternative method: the contact sponge method. This recently developed method was tested on non-treated porous stone materials in a laboratory environment in order to evaluate its performance in comparison with the two existing methods.

Abstract: The ability to detect low concentrations of protein biomarkers is crucial for the early-stage detection of many diseases and therefore indispensable for improving diagnostic devices for healthcare. Here, we demonstrate that by integrating DNA nanotechnologies like DNA origami and aptamers, we can design innovative biosensing concepts for reproducible and sensitive detection of specific targets. DNA origami structures decorated with aptamers were studied as a novel tool to structure the biosensor surface with nanoscale precision in a digital detection bioassay, enabling control of the density, orientation, and accessibility of the bioreceptor to optimize the interaction between target and aptamer. DNA origami was used to control the spatial distribution of an in-house-generated aptamer on superparamagnetic microparticles, resulting in an origami-linked digital aptamer bioassay to detect the main peanut antigen Ara h1 with 2-fold improved signal-to-noise ratio and 15-fold improved limit of detection compared to a digital bioassay without DNA origami. Moreover, the sensitivity achieved was 4 orders of magnitude higher than commercially available and literature-reported enzyme-linked immunosorbent assay techniques. In conclusion, this novel and innovative approach to engineer biosensing interfaces will be of major interest to scientists and clinicians looking for new molecular insights and ultrasensitive detection of a broad range of targets, and, for the next generation of diagnostics.

Abstract: In this study, the aging behavior of microscale zerovalent iron (mZVI) particles was investigated by quantifying the hydrogen gas generated by anaerobic mZVI corrosion in batch degradation experiments. Granular iron and nanoscale zerovalent iron (nZVI) particles were included in this study as controls. Firstly, experiments in liquid medium (without aquifer material) were performed and revealed that mZV1 particles have approximately a 10-30 times lower corrosion rate than nZVI particles. A good correlation was found between surface area normalized corrosion rate (R-SA) and reaction rate constants (K-SA) of PCE, TCE, cDCE and 1,1,1-TCA. Generally, particles with higher degradation rates also have faster corrosion rates, but exceptions do exists. In a second phase, the hydrogen evolution was also monitored during batch tests in the presence of aquifer material and real groundwater. A 4-9 times higher corrosion rate of mZV1 particles was observed under the natural environment in comparison with the aquifer free artificial condition, which can be attributed to the low pH of the aquifer and its buffer capacity. A corrosion model was calibrated on the batch experiments to take into account the inhibitory effects of the corrosion products (dissolved iron, hydrogen and OH-) on the iron corrosion rate. (C) 2014 Elsevier B.V. All rights reserved.

Abstract: A previously unreported Pb-based perovskite PbMoO3 is obtained by high-pressure and high-temperature synthesis. This material crystallizes in the Pm3m cubic structure at room temperature, making it distinct from typical Pb-based perovskite oxides with a structural distortion. PbMoO3 exhibits a metallic behavior down to 0.1 K with an unusual T-sublinear dependence of the electrical resistivity. Moreover, a large specific heat is observed at low temperatures accompanied by a peak in C-P/T-3 around 10 K, in marked contrast to the isostructural metallic system SrMoO3. These transport and thermal properties for PbMoO3, taking into account anomalously large Pb atomic displacements detected through diffraction experiments, are attributed to a low-energy vibrational mode, associated with incoherent off-centering of lone-pair Pb2+ cations. We discuss the unusual behavior of the electrical resistivity in terms of a polaronlike conduction, mediated by the strong coupling between conduction electrons and optical phonons of the local low-energy vibrational mode.

Abstract: Large area, single layer WS2 has a high potential for use in optoelectrical devices with its high photo-luminescence intensity and low response time. In this work, we demonstrate a systematic study of controlled tungsten disulfide (WS2) monolayer growth using chemical vapor deposition (CVD) technique. With a detailed investigation of process parameters such as H-2 gas inclusion into the main carrier gas, growth temperature and duration, we have gained insight into two-dimensional (2D) WS2 synthesis through controlling the seed formations and the radical vapor density associated with WO3. We confirm that H-2 gas, when included to the carrier gas, is directly involved in WO3 reduction due to its reductive reagent nature, which provides a more effective sulfurization and monolayer formation process. Additionally, by changing the CVD growth configuration, hence, increasing the tungsten related vapor density and confining the reactant radicals, we succeed in realizing larger WS(2 )monolayers, which is still a technological challenge in order to utilize these structures for practical applications. Further optimization of the growth procedure is demonstrated by tuning the growth duration to prevent the excess seed formations and additional layers which will possibly limit the device performance of the monolayer flakes or films when applied.

Abstract: The control of damage to individual environmental particles by a laser beam during Raman spectroscopy carried out in ambient air is generally well understood. The nature and control of damage under vacuum conditions (e.g. in the scanning electron microscopy with energy X-ray detection combined with micro-Raman spectroscopyinterfaced SEM-EDX/MRS) are more complex and less well comprehended. The physical and chemical processes that affect the damage caused to small particles by lasers still remain somewhat unclear, but certainly the atmosphere (vacuum/air) and the beam intensity have very significant influences. Furthermore, it has been determined that some particles (e.g. haematite), although stable under an electron beam, are damaged by the laser beam, hampering their analysis. Additionally, when simultaneous analyses by SEM/EDX and MRS are considered, the correct choice of the collection surface plays a crucial role. As a result, the following collection substrates were tested to determine their influence on the laser beam damage process to the particle: silver and aluminium foils and silicon wafers. A test study was performed using artificial examples of haematite (Fe2O3) particles. Exposure of Fe2O3 particles in vacuum to 514- and 785-nm laser radiation often leads to their melting, transformation and evaporation. The dependence of the damage caused by the laser beam on the particle structure is reported here. Molecular and crystallographic changes have also been revealed. Formation of magnetite (as an effect of re-crystallisation) and Raman inactive structures was detected.

Abstract: Synchrotron radiation (SR)-based X-ray methods are powerful analytical tools for several purposes. They are widely used to probe the degradation mechanisms of inorganic artists' pigments in paintings, including chrome yellows (PbCr1-xSxO4; 0 <= x <= 0.8), a class of compounds often found in Van Gogh masterpieces. However, the high intensity and brightness of SR beams raise important issues regarding the potential damage inflicted on the analyzed samples. A thorough knowledge of the SR X-ray sensitivity of each class of pigment in the painting matrix is therefore required to find analytical strategies that seek to minimize the damage for preserving the integrity of the analyzed samples and to avoid data misinterpretation. Here, we employ a combination of Cr K-edge X-ray absorption near-edge structure spectroscopy, Cr-K-beta X-ray emission spectroscopy, and X-ray diffraction to monitor and quantify the effects of SR X-rays on the stability of chrome yellows and related Cr compounds and to define mitigation strategies. We found that the SR X-ray beam exposure induces changes in the oxidation state and local coordination environment of Cr ions and leads to a loss of the compound's crystalline structure. The extent of X-ray damage depends on some intrinsic properties of the samples (chemical composition of the pigment and the presence/absence and nature of the binder). It can be minimized by optimizing the overall fluence/dose released to the samples and by working in vacuum and under cryogenic conditions.