The influence of cation exchange on the possible mechanism of erionite toxicity: A synchrotron-based micro-X-ray fluorescence study on THP-1-derived macrophages exposed to erionite-Na.

Fibrous erionite is the only zeolite classified as Group 1 carcinogen by the International Agency for Research on Cancer (IARC). Carcinogenesis induced by erionite is thought to involve several factors as biopersistence, the iron role and cation exchange processes. To better understand these mechanisms, a detailed investigation at the micro scale was performed, collecting elemental information on iron and cation release and their distribution in biological systems by synchrotron micro-X-ray fluorescence mapping (SR-micro-XRF) and synchrotron micro-X-ray absorption spectroscopy (SR-micro-XANES) at the TwinMic beamline (Elettra synchrotron) and at the ID21 beamline of the European Synchrotron Radiation Facility (ESRF). By microscopy and chemical mapping, highly detailed maps of the chemical and morphological interaction of biological systems with fibres could be produced. In detail, THP-1 cell line derived macrophages, used as in vitro model, were analysed during erionite-Na phagocytosis at different time intervals, after single dose exposure. For comparison, cellular fluorescent probes were also used to evaluate the intracellular free sodium and calcium concentrations. Synchrotron analyses visualised the spatial distribution of both fibre and mineral particle associated metals during the phagocytosis, describing the mechanism of internalisation of erionite-Na and its accessory mineral phases. The intracellular distribution of metals and other cations was mapped to evaluate metal release, speciation changes and/or cation exchange during phagocytosis. The fluorescent probes complemented microchemical data clarifying, and confirming, the cation distribution observed in the SR-micro-XRF maps. The significant cytoplasmic calcium decrease, and the concomitant sodium increase, after the fibre phagocytosis seemed due to activation of plasma membrane cations exchangers triggered by the internalisation while, surprisingly, the ion-exchange capacity of erionite-Na could play a minor role in the disruption of the two cations intracellular homeostasis. These results help to elucidate the role of cations in the toxicity of erionite-treated THP-1 macrophages and add knowledge to its carcinogenicity process.

Nanoscale Chemical Analysis of Thin Film Solar Cell Interfaces Using Tip-Enhanced Raman Spectroscopy.

Interfacial regions play a key role in determining the overall power conversion efficiency of thin film solar cells. However, the nanoscale investigation of thin film interfaces using conventional analytical tools is challenging due to a lack of required sensitivity and spatial resolution. Here, we surmount these obstacles using tip-enhanced Raman spectroscopy (TERS) and apply it to investigate the absorber (Sb2Se3) and buffer (CdS) layers interface in a Sb2Se3-based thin film solar cell. Hyperspectral TERS imaging with 10 nm spatial resolution reveals that the investigated interface between the absorber and buffer layers is far from uniform, as TERS analysis detects an intermixing of chemical compounds instead of a sharp demarcation between the CdS and Sb2Se3 layers. Intriguingly, this interface, comprising both Sb2Se3 and CdS compounds, exhibits an unexpectedly large thickness of 295 ± 70 nm attributable to the roughness of the Sb2Se3 layer. Furthermore, TERS measurements provide compelling evidence of CdS penetration into the Sb2Se3 layer, likely resulting from unwanted reactions on the absorber surface during chemical bath deposition. Notably, the coexistence of ZnO, which serves as the uppermost conducting layer, and CdS within the Sb2Se3-rich region has been experimentally confirmed for the first time. This study underscores TERS as a promising nanoscale technique to investigate thin film inorganic solar cell interfaces, offering novel insights into intricate interface structures and compound intermixing.

There is plenty of asbestos at the bottom. The case of magnesite raw material contaminated with asbestos fibres.

Although all six asbestos minerals (the layer silicate chrysotile and five chain silicate species actinolite asbestos, amosite, anthophyllite asbestos, crocidolite and tremolite asbestos) are classified as carcinogenic, chrysotile is still mined and used in many countries worldwide. Other countries, like Italy, impose zero tolerance for all asbestos species, but conflicting views repress the development of globally uniform treaties controlling international trade of asbestos-containing materials. Hence, countries with more severe legislations against the use of these hazardous materials lack of an international safety net against importation of non-compliant products. This research reports the first discovery of commercial magnesite raw materials contaminated with white asbestos (chrysotile). X-ray powder diffraction and thermogravimetric/thermodifferential measurements showed the presence of serpentine group minerals in both the semi-processed (powder) and quarried material. The univocal identification of chrysotile in the powders was confirmed by its peculiar Raman bands of the OH stretching vibrations between 3500 and 3800 cm-1, with an intense peak at ∼3695 cm-1 and a weak contribution at ∼3647 cm-1. Transmission electron microscope showed that chrysotile forms fibres up to a few microns long and up to 80 nm thick with a nanotube structure characterized by inner channels as large as 30-40 nm. Fibres size analysis obtained by scanning electron microscopy indicates mean length and diameter of 5.95 and 0.109 µm with medians of 2.62 and 0.096 µm, respectively; some among the fibres analysed exhibit the so-called "Stanton size" (i.e., asbestos fibres longer than 8 µm and thinner than 0.25 µm that are strongly carcinogenic). Quantitative analysis showed a chrysotile content around 0.01 wt% not allowed by current regulations in Italy and many other countries. More generally, our findings demonstrate that without shared policies aimed at regulating asbestos circulation on the global market, "asbestos-free" national policies will inevitably fail.

Exploring Cu-Doping for Performance Improvement in Sb2Se3 Photovoltaic Solar Cells.

Copper-doped antimony selenide (Cu-doped Sb2Se3) thin films were deposited as absorber layers in photovoltaic solar cells using the low-temperature pulsed electron deposition (LT-PED) technique, starting from Sb2Se3 targets where part of the Sb was replaced with Cu. From a crystalline point of view, the best results were achieved for thin films with about Sb1.75Cu0.25Se3 composition. In order to compare the results with those previously obtained on undoped thin films, Cu-doped Sb2Se3 films were deposited both on Mo- and Fluorine-doped Tin Oxide (FTO) substrates, which have different influences on the film crystallization and grain orientation. From the current-voltage analysis it was determined that the introduction of Cu in the Sb2Se3 absorber enhanced the open circuit voltage (VOC) up to remarkable values higher than 500 mV, while the free carrier density became two orders of magnitude higher than in pure Sb2Se3-based solar cells.

The Acute Toxicity of Mineral Fibres: A Systematic In Vitro Study Using Different THP-1 Macrophage Phenotypes.

Alveolar macrophages are the first line of defence against detrimental inhaled stimuli. To date, no comparative data have been obtained on the inflammatory response induced by different carcinogenic mineral fibres in the three main macrophage phenotypes: M0 (non-activated), M1 (pro-inflammatory) and M2 (alternatively activated). To gain new insights into the different toxicity mechanisms of carcinogenic mineral fibres, the acute effects of fibrous erionite, crocidolite and chrysotile in the three phenotypes obtained by THP-1 monocyte differentiation were investigated. The three mineral fibres apparently act by different toxicity mechanisms. Crocidolite seems to exert its toxic effects mostly as a result of its biodurability, ROS and cytokine production and DNA damage. Chrysotile, due to its low biodurability, displays toxic effects related to the release of toxic metals and the production of ROS and cytokines. Other mechanisms are involved in explaining the toxicity of biodurable fibrous erionite, which induces lower ROS and toxic metal release but exhibits a cation-exchange capacity able to alter the intracellular homeostasis of important cations. Concerning the differences among the three macrophage phenotypes, similar behaviour in the production of pro-inflammatory mediators was observed. The M2 phenotype, although known as a cell type recruited to mitigate the inflammatory state, in the case of asbestos fibres and erionite, serves to support the process by supplying pro-inflammatory mediators.

Metastable (CuAu-type) CuInS2 Phase: High-Pressure Synthesis and Structure Determination.

We report on the high-pressure solid-state synthesis and the detailed structural characterization of the metastable, CuAu-type CuInS2 (CA-CIS) phase. Although often present in CIS thin films as unwanted phase, it has been never synthesized in pure form, and its effect on the performance of CIS-based solar cells has been long debated. In this work, pure CA-CIS phase is synthesized in bulk polycrystalline form through a high-pressure-high-temperature solid-state reaction. Single-crystal X-rays diffraction reveals the formation of tetragonal CA-CIS (a = 3.9324(5), c = 5.4980(7) Å) either in cation-ordered and disordered phase, pointing out the role of the pressure/temperature increase on the Cu/In ordering. The resistivity measurements performed on CA-CIS show low resistivity and a flat trend vs temperature and, in the case of the ordered phase, highlight a bad-metallic behavior, probably due to a high level of doping. These findings clearly rule out the possibility of a beneficial effect of this phase on the CIS-based thin film solar cells.

Direct growth of germanium nanowires on glass.

We report a detailed characterization of Ge NWs directly grown on glass by a MOVPE system, showing how different growth parameters can affect the final outcome and comparing NWs grown on a monocrystalline Ge(111) substrate with NWs grown on amorphous glass. Our experimental results indicate that the choice of the substrate does not affect any of the relevant morphological, crystallographic or electrical properties of Ge NWs. Lengths are in the 20-30 micrometer range with minimal tapering, while growth rates are very similar to to NWs grown on Ge(111); TEM and Raman characterization show a very good crystallinity of measured nanostructures. We have also analyzed the growth process on glass and we were able to reach a conclusion on the specific growth mechanism for Ge NWs on amorphous substrates. Our findings demonstrate that glass is a valid option as cheap substrate for the mass production of these nanostructures.

A comprehensive study of the magnetic properties of the pyroxenes series CaMgSi2O6-Co2Si2O6 as a function of Co content.

We report a detailed study on the magnetic properties of the pyroxene series M2M1Si2O6, with M2 = Ca and M1 = Mg, where magnesium and then calcium are progressively substituted by cobalt. For cobalt site occupancy larger than 0.7 at the M1 site, a collinear antiferromagnetic phase is detected for T < T N1 = 12 K with a monodimensional character (i.e. M1 site intra-chain order parallel to c axis). Moreover the magnetization easy axis has been estimated to lie roughly along the [1 0 1] direction. Cobalt content ⩾0.5 at the M2 site (overall content 1.5) determines the formation of a new independent antiferromagnetic order with higher Néel temperature, involving only the M2 site intra-chain interactions. The incoming M2 site order is accompanied by a lowering of the space symmetry which yields to a weakly ferromagnetic resultant due to spin canted distribution of the magnetic moments either along the M1 or M2 chains. Furthermore, metamagnetic transitions are observed for both M1 and M2 site intra-chain orders at relatively low critical magnetic fields, around 2 T, suggesting that this series of pyroxenes can be used as a model system for investigating the fundamental aspects of magnetism in the matter.

Raman spectroscopy as a PAT for pharmaceutical blending: Advantages and disadvantages.

Raman spectroscopy has been positively evaluated as a tool for the in-line and real-time monitoring of powder blending processes and it has been proved to be effective in the determination of the endpoint of the mixing, showing its potential role as process analytical technology (PAT). The aim of this study is to show advantages and disadvantages of Raman spectroscopy with respect to the most traditional HPLC analysis. The spectroscopic results, obtained directly on raw powders, sampled from a two-axis blender in real case conditions, were compared with the chromatographic data obtained on the same samples. The formulation blend used for the experiment consists of active pharmaceutical ingredient (API, concentrations 6.0% and 0.5%), lactose and magnesium stearate (as excipients). The first step of the monitoring process was selecting the appropriate wavenumber region where the Raman signal of API is maximal and interference from the spectral features of excipients is minimal. Blend profiles were created by plotting the area ratios of the Raman peak of API (AAPI) at 1598cm-1 and the Raman bands of excipients (AEXC), in the spectral range between 1560 and 1630cm-1, as a function of mixing time: the API content can be considered homogeneous when the time-dependent dispersion of the area ratio is minimized. In order to achieve a representative sampling with Raman spectroscopy, each sample was mapped in a motorized XY stage by a defocused laser beam of a micro-Raman apparatus. Good correlation between the two techniques has been found only for the composition at 6.0% (w/w). However, standard deviation analysis, applied to both HPLC and Raman data, showed that Raman results are more substantial than HPLC ones, since Raman spectroscopy enables generating data rich blend profiles. In addition, the relative standard deviation calculated from a single map (30 points) turned out to be representative of the degree of homogeneity for that blend time.

Raman Investigation of Precious Jewelry Collections Preserved in Paolo Orsi Regional Museum (Siracusa, Sicily) Using Portable Equipment.

This work is a part of a large scientific project aimed at highlighting the potential of portable Raman equipment in characterizing jewelry materials preserved in museums, carried out in collaboration with gemologists and archeologists. In detail, we report the results of a measurement campaign performed for the study of gems and jewels preserved in the well-known Medagliere section at the Paolo Orsi Regional Museum of Siracusa (Sicily). The studied materials consist of exquisite examples of engraved loose gems and really rare examples of Hellenistic-Roman jewels, mainly coming from relevant Sicilian archaeological sites. Portable Raman measurements have been carried out using two instruments equipped with different excitation wavelengths. The obtained results have allowed for a complete characterization of the studied gemological materials, also suggesting sometimes misclassification for some valuable objects and gems.

Oxidative and pro-inflammatory effects of cobalt and titanium oxide nanoparticles on aortic and venous endothelial cells.

Ultra-fine particles have recently been included among the risk factors for the development of endothelium inflammation and atherosclerosis, and cobalt (CoNPs) and titanium oxide nanoparticles (TiNPs) have attracted attention because of their wide range of applications. We investigated their toxicity profiles in two primary endothelial cell lines derived from human aorta (HAECs) and human umbilical vein (HUVECs) by comparing cell viability, oxidative stress, the expression of adhesion molecules and the release of chemokines during NP exposure. Both NPs were very rapidly internalised, and significantly increased adhesion molecule (ICAM-1, VCAM-1, E-selectin) mRNA and protein levels and the release of monocyte chemoattractant protein-1 (MCP-1) and interleukin 8 (IL-8). However, unlike the TiNPs, the CoNPs also induced time- and concentration-dependent metabolic impairment and oxidative stress without any evident signs of cell death or the induction of apoptosis. There were differences between the HAECs and HUVECs in terms of the extent of oxidative stress-related enzyme and vascular adhesion molecule expression, ROS production, and pro-inflammatory cytokine release despite the similar rate of NP internalisation, thus indicating endothelium heterogeneity in response to exogenous stimuli. Our data indicate that NPs can induce endothelial inflammatory responses via various pathways not involving only oxidative stress.

Titanium dioxide nanoparticles promote arrhythmias via a direct interaction with rat cardiac tissue.

BACKGROUND: In light of recent developments in nanotechnologies, interest is growing to better comprehend the interaction of nanoparticles with body tissues, in particular within the cardiovascular system. Attention has recently focused on the link between environmental pollution and cardiovascular diseases. Nanoparticles <50 nm in size are known to pass the alveolar-pulmonary barrier, enter into bloodstream and induce inflammation, but the direct pathogenic mechanisms still need to be evaluated. We thus focused our attention on titanium dioxide (TiO2) nanoparticles, the most diffuse nanomaterial in polluted environments and one generally considered inert for the human body. METHODS: We conducted functional studies on isolated adult rat cardiomyocytes exposed acutely in vitro to TiO2 and on healthy rats administered a single dose of 2 mg/Kg TiO2 NPs via the trachea. Transmission electron microscopy was used to verify the actual presence of TiO2 nanoparticles within cardiac tissue, toxicological assays were used to assess lipid peroxidation and DNA tissue damage, and an in silico method was used to model the effect on action potential. RESULTS: Ventricular myocytes exposed in vitro to TiO2 had significantly reduced action potential duration, impairment of sarcomere shortening and decreased stability of resting membrane potential. In vivo, a single intra-tracheal administration of saline solution containing TiO2 nanoparticles increased cardiac conduction velocity and tissue excitability, resulting in an enhanced propensity for inducible arrhythmias. Computational modeling of ventricular action potential indicated that a membrane leakage could account for the nanoparticle-induced effects measured on real cardiomyocytes. CONCLUSIONS: Acute exposure to TiO2 nanoparticles acutely alters cardiac excitability and increases the likelihood of arrhythmic events.

Synthesis and characterization of nanocrystalline TiO2 with application as photoactive coating on stones.

UNLABELLED: Self-cleaning photocatalytic coatings for biocalcarenite stones, based on TiO2 nanoparticles obtained by sol-gel processes at different pH values and also adding gold particles, have been investigated. The selected test material is a biocalcarenite named "pietra di Lecce" (Lecce stone), outcropping in Southern Italy. Scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and Raman investigations were carried out to characterize the TiO2 nanoparticles and coatings. Nanocrystalline anatase and, to a lesser extent, brookite phases are obtained. Photocatalytic activity of the TiO2 sols and of the coatings on "pietra di Lecce" was assessed under ultraviolet irradiation, monitoring methyl orange (MeO) dye degradation as a function of time. To evaluate the harmlessness of the treatment, colorimetric tests and water absorption by capillarity were performed. The results show good photodegradation rates for titania nanosols, particularly when putting in Au particles, whereas a satisfactory chromatic compatibility between the sol and the surface of the calcarenite is found only without Au addition. HIGHLIGHTS: Sols of nanocrystalline titania at different pH values and with Au particles were prepared and characterized. Satisfactory photodegradation of MeO by the sols in solution and on calcarenite-coated surfaces is obtained. The addition of Au particles improves the photodegradation activity but gives poor chromatic results on "pietra di Lecce."

Characterisation of a portable Raman spectrometer for in situ analysis of art objects.

During the last decades, Raman spectroscopy has grown to an established analytical technique in archaeometry, art analysis and conservation science. Mobile Raman instruments were designed to be used for in situ characterisation and identification of inorganic and organic materials in art and archaeometry. This research paper aims to point out several aspects that need to be considered when selecting a mobile Raman spectrometer for in situ archaeometrical studies. We describe an approach to evaluate these parameters and apply this to a dual laser portable Raman spectrometer. Twofold characterisation of mobile Raman instrumentation for art analysis: (i) investigation of spectroscopic characteristics such as (amongst others) spectral resolution, spectral window, signal to noise ratio and limit of detection; (ii) evaluation of specific properties that are useful for mobile studies in archaeometry. These include options for easy positioning and focussing, the ability to reduce laser power on the surface of the art object and the working distance between the probehead and the artefact. Finally, the research was completed with field tests by studying the pigments of a mediaeval wall painting.

Micro-Raman study of copper hydroxychlorides and other corrosion products of bronze samples mimicking archaeological coins.

Three bronze samples created by CNR-ISMN (National Research Council-Institute of Nanostructured Materials) to be similar to Punic and Roman coins found in Tharros (OR, Sardinia, Italy) were studied to identify the corrosion products on their surfaces and to evaluate the reliability of the reproduction process. Micro-Raman spectroscopy was chosen to investigate the corroded surfaces because it is a non-destructive technique, it has high spatial resolution, and it gives the opportunity to discriminate between polymorphs and to correlate colour and chemical composition. A significant amount of green copper hydroxychlorides (Cu(2)(OH)(3)Cl) was detected on all the coins. Their discrimination by Raman spectroscopy was challenging because the literature on the topic is currently confusing. Thus, it was necessary to determine the characteristic peaks of atacamite, clinoatacamite, and the recently discovered anatacamite by acquiring Raman spectra of comparable natural mineral samples. Clinoatacamite, with different degrees of order in its structure, was the major component identified on the three coins. The most widespread corrosion product, besides hydroxychlorides, was the red copper oxide cuprite (Cu(2)O). Other corrosion products of the elements of the alloy (laurionite, plumbonacrite, zinc carbonate) and those resulting from burial in the soil (anatase, calcite, hematite) were also found. This study shows that identification of corrosion products, including discrimination of copper hydroxychlorides, could be accomplished by micro-Raman on valuable objects, for example archaeological findings or works of art, avoiding any damage because of extraction of samples or the use of a destructive analytical technique.

Applications of Raman spectroscopy to gemology.

Being nondestructive and requiring short measurement times, a low amount of material, and no sample preparation, Raman spectroscopy is used for routine investigation in the study of gemstone inclusions and treatments and for the characterization of mounted gems. In this work, a review of the use of laboratory Raman and micro-Raman spectrometers and of portable Raman systems in the gemology field is given, focusing on gem identification and on the evaluation of the composition, provenance, and genesis of gems. Many examples are shown of the use of Raman spectroscopy as a tool for the identification of imitations, synthetic gems, and enhancement treatments in natural gemstones. Some recent developments are described, with particular attention being given to the semiprecious stone jade and to two important organic materials used in jewelry, i.e., pearls and corals.

Micro-Raman spectroscopy as a routine tool for garnet analysis.

A rapid system to obtain molar compositions of minerals belonging to the garnet group by means of Raman spectroscopy is illustrated here. A series of standard garnets, whose composition was determined by means of Wavelength Dispersive System (WDS) electron microprobe measurements, was used to correlate the wavenumbers of the different Raman peaks with chemical composition. A simple software routine was then developed in order to obtain garnet molar composition starting from the Raman spectrum, based on the assumption that in a solid solution belonging to the garnet family the Raman wavenumbers are linear combinations of end member wavenumbers, weighted by their molar fraction. The choice of the Raman bands used for the calculations and their behaviour are also discussed. The method, called MIRAGEM (Micro-Raman Garnets Evaluation Method), was then tested on a second series of garnets with satisfactory results.

Raman spectroscopy as an effective tool for high-resolution heavy-mineral analysis: examples from major Himalayan and Alpine fluvio-deltaic systems.

Raman spectroscopy represents a new way to obtain detailed comprehensive information on heavy-mineral assemblages. In this work are presented several examples from major Alpine (Po River) and Himalayan (Ganga and Brahmaputra Rivers) fluvio-deltaic sands. Our attention was focused on the chemical properties of garnet, which is a widespread mineral in orogenic sediments, easy to be identified, and relatively stable during both equatorial weathering and intrastratal dissolution. Garnet grains were studied in different samples representative of various depositional environments (fluvial bar, fluvial levee, shoreface, beach berm, eolian dune), in order to investigate specifically the hydraulic behaviour of grains with different density in different hydrodynamic conditions. Raman spectra and semi-quantitative analysis of Raman shifts allowed us to rapidly determine the distribution of garnet types in each sample in order to obtain chemical composition, to calculate the density of each garnet, and finally to infer their respective provenance. This manuscript presents one possible application of the "MIRAGEM" method described by Bersani et al. in this volume. References, data sets and details on the analytical routine are widely explained in the above mentioned work.

Green pigments of the Pompeian artists' palette.

Green colored samples on wall paintings and green powder from a pigment pot found in Pompeii area are investigated by micro-Raman, FT-IR and, for one sample, SEM-EDX. To obtain the green color, green earths and malachite were used, together with mixture of Egyptian blue and yellow ochre. The mineralogical identification of the green earths has been attempted through the comparison of the vibrational features, discriminating between celadonite and glauconite spectra. Traces of a modern synthetic pigment containing copper phthalocyanine were found in a fresco fragment.

Polarization holographic gratings in hybrid solgel films doped with Disperse Red 1.

Polarization holographic gratings in sp configuration are written at 488 nm in photorefractive organic-inorganic films based on SiO2. The films, prepared by a solgel technique, contain Disperse Red 1, carbazole units, and 2,4,7-trinitro-9-fluorenone. The gratings are characterized by their diffraction efficiency for a 632.8-nm probe. The polarization gratings act as a half-wave plate, and the diffraction efficiency is independent of the polarization direction of the probe.