Abstract: This paper critically compares the performance of four non-invasive techniques that match the accuracy, flexibility, time-efficiency, and transportability required for in situ characterization of leaded glass windows: macroscopic X-ray fluorescence imaging (MA-XRF), UV-Vis-NIR, Raman spectroscopy, and infrared thermography (IRT). In order to compare the techniques on equal grounds, all techniques were tested independently of each other by separate research groups on the same historical leaded window tentatively dated to the 17th century, without prior knowledge. The aim was to assess the ability of these techniques to document the conservation history of the window by classifying and grouping the colorless glass panes, based on differences in composition. IRT, MA-XRF and UV-Vis-NIR spectroscopy positively distinguished at least two glass groups, with MA-XRF providing the most detailed chemical information. In particular, based on the ratio between the network modifier (K) and network stabilizer (Ca) and on the level of colorants and decolorizers (Fe, Mn, As), the number of plausible glass families could be strongly reduced. In addition, UV-Vis-NIR detected cobalt at ppm level and gave more specific information on the chromophore Fe2+/Fe(3+)ratio. Raman spectroscopy was hampered by fluorescence caused by the metal ions of the decolorizer in most of the panes, but nevertheless identified one group as HLLA.

Abstract: The ongoing conservation treatment program of the Ghent Altarpiece by Hubert and Jan Van Eyck, one of the iconic paintings of the west, has revealed that the designs of the paintings were changed several times, first by the original artists, and then during later restorations. The central motif, The Lamb of God, representing Christ, plays an essential iconographic role, and its depiction is important. Because of the prevalence of lead white, it was not possible to visualize the Van Eycks' original underdrawing of the Lamb, their design changes, and the overpaint by later restorers with a single spectral imaging modality. However, by using elemental (x-ray fluorescence) and molecular (infrared reflectance) imaging spectroscopies, followed by analysis of the resulting data cubes, the necessary chemical contrast could be achieved. In this way, the two complementary modalities provided a more complete picture of the development and changes made to the Lamb.

Abstract: Background The diagnosis of active Toxocara canis infections in humans is challenging. Larval stages of T. canis do not replicate in human tissues and disease may result from infection with a single T. canis larva. Recently, we developed a nanobody-based electrochemical magnetosensor assay with superior sensitivity to detect T. canis excretory-secretory (TES) antigens. Here, we evaluate the performance of the assay in children from an Ecuadorian birth cohort that followed children to five years of age. Methods Samples were selected based on the presence of peripheral blood eosinophilia and relative eosinophil counts. The samples were analyzed by the nanobody-based electrochemical magnetosensor assay, which utilizes a bivalent biotinylated nanobody as capturing agent on the surface of streptavidin pre-coated paramagnetic beads. Detection was performed by a different nanobody chemically labelled with horseradish peroxidase. Results Of 87 samples tested, 33 (38%) scored positive for TES antigen recognition by the electrochemical magnetosensor assay. The average concentration of TES antigen in serum was 2.1 ng/ml (SD = 1.1). The positive result in the electrochemical assay was associated with eosinophilia > 19% (P = 0.001). Parasitological data were available for 57 samples. There was no significant association between positivity by the electrochemical assay and the presence of other soil-transmitted helminth infections. Conclusions Our nanobody-based electrochemical assay provides highly sensitive quantification of TES antigens in serum and has potential as a valuable tool for the diagnosis of active human toxocariasis.

Abstract: Solid carbon deposition is a persistent challenge in dry reforming of methane (DRM), affecting both classical and plasma-based processes. In this work, we use a microwave plasma in reverse vortex flow configuration to overcome this issue in CO₂/CH₄plasmas. Indeed, this configuration efficiently mitigates carbon deposition, enabling operation even with pure CH₄feed gas, in contrast to other configurations. At the same time, high reactor performance is achieved, with CO₂and CH₄conversions reaching 33% and 44% respectively, at an energy cost of 14 kJ L⁻¹for a CO₂ : CH₄ratio of 1 : 1. Laser scattering and optical emission imaging demonstrate that the shorter residence time in reverse vortex flow lowers the gas temperature in the discharge, facilitating a shift from full to partial CH₄pyrolysis. This underscores the pivotal role of flow configuration in directing process selectivity, a crucial factor in complex chemistries like CO₂/CH₄mixtures and very important for industrial applications.

Abstract: In this study, reactivity of single-layer GaAs against Ge atoms is studied by means of ab initio density functional theory calculations. Firstly, it is shown that Ge atoms interact quite strongly with the GaAs layer which allows the formation of Ge islands while it hinders the growth of detached germanene monolayers. It is also predicted that adsorption of Ge atoms on GaAs single-layer lead to formation of two novel stable single-layer crystal structures, namely 1H-GaGeAs and 1H(A)-GaGeAs. Both the total energy optimizations and the calculated vibrational spectra indicate the dynamical stability of both single layer structures. Moreover, although both structures crystallize in 1H phase, 1H-GaGeAs and 1H(A)-GaGeAs exhibit distinctive vibrational features in their Raman spectra which is quite important for distinguishing the structures. In contrast to the semiconducting nature of single-layer GaAs, both polytypes of GaGeAs exhibit metallic behavior confirmed by the electronic band dispersions. Furthermore, the linear-elastic constants, in-plane stiffness and Poisson ratio, reveal the ultrasoft nature of the GaAs and GaGeAs structures and the rigidity of GaAs is found to be slightly enhanced via Ge adsorption. With their stable, ultra-thin and metallic properties, predicted single-layer GaGeAs structures can be promising candidates for nanoscale electronic and mechanical applications.

Abstract: Herein, using first-principles calculations the structural and electronic properties of the Ti(2)CO(2)MXene monolayer with and without oxygen vacancies are systematically investigated with different defect concentrations and patterns, including partial, linear, local, and hexagonal types. The Ti(2)CO(2)monolayer is found to be a semiconductor with a bandgap of 0.35 eV. The introduction of oxygen vacancies tends to increase the bandgap and leads to electronic phase transitions from nonmagnetic semiconductors to half-metals. Moreover, the semiconducting characteristic of O-vacancy Ti(2)CO(2)can be adjusted via electric fields, strain, and F-atom substitution. In particular, an electric field can be used to alter the nonmagnetic semiconductor of O-vacancy Ti(2)CO(2)into a magnetic one or into a half-metal, whereas the electronic phase transition from a semiconductor to metal can be achieved by applying strain and F-atom substitution. The results provide a useful guide for practical applications of O-vacancy Ti(2)CO(2)monolayers in nanoelectronic and spinstronic nanodevices.

Abstract: Within the heritage field, the application of strain gauges on wood surfaces is a little-explored but inexpensive and effective method to analyse the environmental appropriateness of rooms for the wooden heritage collections they contain. This contribution proposes a wood sensor connected to a data logger to identify short moments with an elevated risk of harm. Two experiments were performed to obtain insights pertaining to the applicability of wood sensors to evaluate preservation conditions. (1) The representativeness of strain gauges on dummies was tested for their use in evaluating the preservation conditions of a range of wooden objects exposed to the same environment. For this, three situations were mimicked: a bare wood surface, a wood surface covered with a preparation layer, and a wood surface covered with a preparation and varnish layer. (2) The usability of strain gauges to monitor the wood behaviour in real-time measurements was tested with a monitoring campaign of almost two years in a church where a new heating system was installed. The results of both experiments are promising, and the authors encourage a broader application of strain gauges in the heritage field.

Abstract: The seasonal changes of a large set of atmospheric pollutants (i.e., gases, water-soluble aerosols, metallic/elemental components and black carbon (BC) content) have been studied over the southern bight of the North Sea (the Belgian Continental Shelf) and the English Channel during several marine sampling campaigns, carried out in 2010-2011. A coastal research station at De Haan, Belgium was concurrently used as a background air monitoring site. Size-segregated aerosols (PM1, PM2.5-1, PM10-2.5) were analyzed for particulate mass, elemental content and water-soluble (ionic) compounds, while the equivalent BC content in PM10 was monitored with an Aethalometer. The results clearly demonstrated that the aerosols originating from ship exhaust emissions contributed mostly to fine fraction (PM1), and to a lesser extent to medium-sized fraction (PM2.5-1), whereas components of sea spray and of mineral/soil origin were dominating in the medium-size and coarse aerosol fractions. Looking at seasonal differences, more ship emission related components occurred in the fine and medium-sized PM during winter. Mineral aerosol components were more apparent in coarse PM and especially during the cold season, increased levels were noted. Similarly, higher concentrations of marine fine PM were found during winter, likely due to more extensive ship emissions and/or calm weather conditions. Gaseous pollutants (e.g., HNO2, HNO3, HCl, SO2, NH3) originating from exhaust fumes of ocean-going ships mostly reached the maximum levels in the cold season as well, thus supporting the more intense formation of secondary aerosols. The seasonal trends of total (inorganic) ionic species sampled on the open sea and at the coastal station were usually similar to those of the corresponding PM masses, peaking in the cold season. Sea salt bound fine sulfate and nitrate peaked in spring or the cold season for marine areas, whereas for the coastal site they clearly reached the maximum in the cold season. Ammonium-bound nitrates and sulfates in each PM fraction reached their peak air levels in the cold season over marine sites. Similar seasonal trends could be observed for the coastal station. The general tendency of aerosol distribution over the study areas was independent of the sampling site: the higher the aerosol mass on the open sea with ship traffic, the higher the suspended particulate mass sampled at the coast.

Abstract: When monolayer (ML) MoS2 is placed on a substrate, the proximity-induced interactions such as the Rashba spin-orbit coupling (RSOC) and exchange interaction (EI) can be introduced. Thus, the electronic system can behave like a spintronic device. In this study, we present a theoretical study on how the presence of the RSCO and EI can lead to the band splitting, the lifting of the valley degeneracy and to the spin polarization in n- and p-type ML MoS2. We find that the maxima of the in-plane spin orientation in the conduction and valence bands in ML MoS2 depend on the Rashba parameter and the effective Zeeman field factor. At a fixed Rashba parameter, the minima of the split conduction band and the maxima of the split valence band along with the spin polarization in ML MoS2 can be tuned effectively by varying the effective Zeeman field factor. On the basis that the EI can be induced by placing the ML MoS2 on a ferromagnetic substrate or by magnetic doping in ML MoS2, we predict that the interesting spintronic effects can be observed in n- and p-type ML MoS2. This work can be helpful to gain an in-depth understanding of the basic physical properties of ML MoS2 for application in advanced electronic and optoelectronic devices.

Abstract: This paper presents the results of X-ray fluorescence (XRF) analysis of bricks sampled from historical places in Pernambuco, a state in the northeastern region of Brazil. In this study, twenty bricks found in historical sites were analyzed. Two bricks made in the 17th century, presumably used as ballast in ships coming from Holland, five locally manufactured bricks: one from 18th century, three from 19th century, and one from 20th century, and thirteen bricks collected from a recent Archeological investigation of Alto da Se, in the town of Olinda. Qualitative determination of the chemical elements present in the samples was undertaken using a self-assembled portable XRF system based on a compact X-ray tube and a thermoelectrically cooled Si-PIN photodiode system, both commercially available. X-ray diffraction analysis was also carried out to assess the crystalline mineral phases present in the bricks. The results showed that quartz (SiO2) is the major mineral content in all bricks. Although less expressive in the XRD patterns, mineral phases of illite, kaolinite, anorthite, and rutile are also identified. The trace element distribution patterns of the bricks, determined by the XRF technique, is dominated by Fe and, in decreasing order, by K, Ti, Ca, Mn, Zr, Rb, Sr, Cr, and Y with slight differences among them. Analyses of the chemical compositional features of the bricks, evaluated by principal component analysis of the XRF datasets, allowed the samples to be grouped into five clusters with similar chemical composition. These cluster groups were able to identify both age and manufacturing sites. Dutch bricks prepared with different geological clays compositions were defined.

Abstract: The illicit consumption of heroin is an increasing concern in our society. For this reason, rapid analytical methods to seize heroin samples in the field are of paramount importance to hinder drug trafficking, and thus prevent the availability of heroin in the drug market. The present work reports on the enriched electrochemical fingerprint of heroin, allowing its selective detection in street samples, based on the use of electrochemical pretreated screen printed electrodes (p-SPE). The voltammetric identification is built on two oxidation peaks of both heroin and its degradation product 6-monoacetylmorphine (6-MAM), generated in alkaline conditions. Interestingly, an anodic pretreatment of the screen printed electrodes (SPE) shifts the peak potential of paracetamol (the most encountered cutting agent in heroin seizures), allowing the detection of 6-MAM peak, overlapping with the paracetamol signal in the case of untreated SPE. Subsequently, the characterization of the p-SPE with scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, Raman and Fourier transform infrared (FTIR) spectroscopy is provided to demonstrate local changes on the surface of the electrode. From an analytical perspective, p-SPE provide higher sensitivity (0.019 μA μM-1), excellent reproducibility (6-MAM, RSD = 2.85%, and heroin RSD = 0.91%, n = 5) and lower limits of detection (LOD) (5.2 μM) in comparison to untreated SPE. The proposed protocol which integrates a tailor-made script is interrogated against common cutting agents, and finally, validated with the screening of 14 street samples, also analyzed by standard methods. Besides, a comparison with portable spectroscopic techniques on the confiscated samples shows the better performance of the electrochemical strategy. Overall, this sensing approach offers promising results for the rapid on-site profiling of suspicious heroin samples, also in the presence of paracetamol.

Abstract: The cleaning of two-dimensional (2D) materials is an essential step in the fabrication of future devices, leveraging their unique physical, optical, and chemical properties. Part of these emerging 2D materials are transition metal dichalcogenides (TMDs). So far there is limited understanding of the cleaning of “monolayer” TMD materials. In this study, we report on the use of downstream H₂plasma to clean the surface of monolayer WS₂grown by MOCVD. We demonstrate that high-temperature processing is essential, allowing to maximize the removal rate of polymers and to mitigate damage caused to the WS₂in the form of sulfur vacancies. We show that low temperature in situ carbonyl sulfide (OCS) soak is an efficient way to resulfurize the material, besides high-temperature H₂S annealing. The cleaning processes and mechanisms elucidated in this work are tested on back-gated field-effect transistors, confirming that transport properties of WS₂devices can be maintained by the combination of H₂plasma cleaning and OCS restoration. The low-damage plasma cleaning based on H₂and OCS is very reproducible, fast (completed in a few minutes) and uses a 300 mm industrial plasma etch system qualified for standard semiconductor pilot production. This process is, therefore, expected to enable the industrial scale-up of 2D-based devices, co-integrated with silicon technology.

Abstract: We calculate the Curie temperature of layered ferromagnets, chromium tri-iodide (CrI3), chromium tri-bromide (CrBr3), chromium germanium tri-telluride (CrGeTe3), and the Ned temperature of a layered antiferromagnet iron di-chloride (FeCl2), using first-principles density functional theory calculations and Monte Carlo simulations. We develop a computational method to model the magnetic interactions in layered magnetic materials and calculate their critical temperature. We provide a unified method to obtain the magnetic exchange parameters (J) for an effective Heisenberg Hamiltonian from first principles, taking into account both the magnetic ansiotropy as well as the out-of-plane interactions. We obtain the magnetic phase change behavior, in particular the critical temperature, from the susceptibility and the specific-heat, calculated using the three-dimensional Monte Carlo (METROPOLIS) algorithm. The calculated Curie temperatures for ferromagnetic materials (CrI3, CrBr3, and CrGeTe3), match well with experimental values. We show that the interlayer interaction in bulk CrI3 with R (3) over bar stacking is significantly stronger than the C2/m stacking, in line with experimental observations. We show that the strong interlayer interaction in R (3) over bar CrI3 results in a competition between the in-plane and the out-of-plane magnetic easy axes. Finally, we calculate the Ned temperature of FeCl2 to be 47 +/- 8 K and show that the magnetic phase transition in FeCl2 occurs in two steps with a high-temperature intralayer ferromagnetic phase transition and a low-temperature interlayer antiferromagnetic phase transition.

Abstract: In order to investigate the structural, vibrational, electronic, and mechanical features of single-layer ReTe2 first-principles calculations are performed. Dynamical stability analyses reveal that single-layer ReTe2 crystallize in a distorted phase while its 1H and 1T phases are dynamically unstable. Raman spectrum calculations show that single-layer distorted phase of ReTe2 exhibits 18 Raman peaks similar to those of ReS2 and ReSe2. Electronically, single-layer ReTe2 is shown to be an indirect gap semiconductor with a suitable band gap for optoelectronic applications. In addition, it is found that the formation of Re-units in the crystal induces anisotropic mechanical parameters. The in-plane stiffness and Poisson ratio are shown to be significantly dependent on the lattice orientation. Our findings indicate that single-layer form of ReTe2 can only crystallize in a dynamically stable distorted phase formed by the Re-units. Single-layer of distorted ReTe2 can be a potential in-plane anisotropic material for various nanotechnology applications.

Abstract: Sr2CrO2Cr2As2 and Ba2CrO2Cr2As2 with Cr2+ ions in CrO2 sheets and in CrAs layers crystallize with the Sr2Mn3Sb2O2 structure (space group I4/mmm, Z = 2) and lattice parameters a = 4.00800(2) Å, c = 18.8214(1) Å (Sr2CrO2Cr2As2) and a = 4.05506(2) Å, c = 20.5637(1) Å (Ba2CrO2Cr2As2) at room temperature. Powder neutron diffraction reveals checkerboard-type antiferromagnetic ordering of the Cr2+ ions in the arsenide layers below TN1Sr, of 600(10) K (Sr2CrO2Cr2As2) and TN1Ba 465(5) K (Ba2CrO2Cr2As2) with the moments initially directed perpendicular to the layers in both compounds. Checkerboard-type antiferromagnetic ordering of the Cr2+ ions in the oxide layer below 230(5) K for Ba2CrO2Cr2As2 occurs with these moments also perpendicular to the layers, consistent with the orientation preferences of d4 moments in the two layers. In contrast, below 330(5) K in Sr2CrO2Cr2As2, the oxide layer Cr2+ moments are initially oriented in the CrO2 plane; but on further cooling, these moments rotate to become perpendicular to the CrO2 planes, while the moments in the arsenide layers rotate by 90° with the moments on the two sublattices remaining orthogonal throughout [behavior recently reported independently by Liu et al. [Liu et al. Phys. Rev. B 2018, 98, 134416]]. In Sr2CrO2Cr2As2, electron diffraction and high resolution powder X-ray diffraction data show no evidence for a structural distortion that would allow the two Cr2+ sublattices to couple, but high resolution neutron powder diffraction data suggest a small incommensurability between the magnetic structure and the crystal structure, which may account for the coupling of the two sublattices and the observed spin reorientation. The saturation values of the Cr2+ moments in the CrO2 layers (3.34(1) μB (for Sr2CrO2Cr2As2) and 3.30(1) μB (for Ba2CrO2Cr2As2)) are larger than those in the CrAs layers (2.68(1) μB for Sr2CrO2Cr2As2 and 2.298(8) μB for Ba2CrO2Cr2As2) reflecting greater covalency in the arsenide layers.