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Today, cancer is one of the main health issues faced in the workplace, with asbestos an important carcinogen in the occupational environment. Among the asbestos minerals, chrysotile is the main species of socio-economic and industrial relevance. Although chrysotile asbestos is classified as a “carcinogenic substance” by the International Agency for Research on Cancer (IARC), this fiber is still mined and used in Russia. The effective health hazard posed by the Russian commercial chrysotile has not been quantitatively assessed to date. In this work, the potential toxicity/pathogenicity of Russian chrysotile was quantitatively determined using the fiber potential toxicity index (FPTI) model. This model was applied to a representative commercial chrysotile from the Orenburg region, Russia, whose morphometric, crystal-chemical, surface activity, and biodurability related parameters were determined. We have quantitatively assessed that the toxicity/pathogenicity potential of Russian chrysotile (FPTI = 2.4) is lower than that of amphibole asbestos species but higher than the threshold limit set for “safe” mineral fibers (FPTI = 2.0), although it does not contain impurities of amphibole asbestos. Differences with other chrysotile samples were discussed, and it was found that the investigated Russian commercial chrysotile shares several features with the Italian Balangero chrysotile, indicating that widespread concern on commercial Russian chrysotile is justified.

We investigated the mineralogical and chemical signatures of enigmatic microspherules commonly recovered in conodont residues and referred to in literature as 'conodont pearls.' Comparison between these 'pearls,' associated conodonts and other phosphatic skeletal elements present in the same stratigraphical level was run in an effort to reveal any possible relation between 'conodont pearls' and the joined groups so to finally provide a response on the affinity of these spherules.

Background: In recent times, also in compliance with several sustainable agriculture rules, the use of soil conditioners, such as zeolites, progressively increased. Zeolites are minerals characterized by unique physical‐chemical properties, which make them able to control the mobility of water, ammonium and other cations in soils. As zeolites do not exhaust their properties over time, it would be appropriate to check for their correct distribution in the amended soil. Aims: We present an efficient and inexpensive method to measure the point‐to‐point amount of zeolite spread in the soil through the analysis of a single (i.e., one peak) X‐ray powder diffraction signal. Methods: The procedure requires the preparation of a calibration curve using known quantities of non‐amended soil, zeolite and of an internal reference standard. The amount of zeolite is calculated by comparing the intensities of the selected signal in unknown sample with its analogue in the calibration curve. Results: The method returned a small underestimation (about 12 weight %) of the measured values compared to those expected which depend nearly exclusively on the valuation of the apparent density of the soil, whereas it is not affected by the type and number of phases present in the soil and in the amendant. Conclusions: The proposed method allows to check for the regular distribution of zeolite in soil, but we are confident that it could also be conveniently generalized to all the applications that require the quantitative determination of mono or polyphasic crystalline materials within a complex mixture like soil.

This work reports the biostratigraphic assessment and the chemical and mineralogical characterization of a zeolitized and barium-rich volcanic pyroclastic bed outcropping in the lower Secchia Valley (Northern Apennines, Italy), very close to the boundary between the Ranzano and the Monte Piano Formations. To our knowledge, it is the older so far documented in the Emilian Epiligurian Succession as, through nannofossil biostratigraphy, we have documented an early Oligocene age (Rupelian CNO1 nannofossil zone) for the enclosing sediments. The chemical and mineralogical composition, the latter obtained through a multi- analytical approach combining X-ray powder diffraction (Rietveld- RIR method) with thermal analyses coupled with evolved gas mass spectrometry, revealed large amounts of Ba-rich phillipsite, baryte, volcanic glass and subordinate quantities of sanidine and plagioclase; on the other hand, phlogopite, idiomorphic plagioclase and femic minerals, frequently found in younger volcanic layers of the Ranzano Formation, here are absent. The quantitative mineralogical assessment together with mineral associations suggest that diagenesis did not play a relevant role in the crystallization of phillipsite, but its role cannot be neglected for the crystallization of baryte. Hypothesis on the genesis and transformation of the original material and on the possible correlation with the coeval calc-alkaline magmatic sources in the circum-Mediterranean area were considered, but no definitive conclusion has been reached.

Brucite is a hydroxide mineral [Mg(OH)2] with a hexagonal structure (space group P3m1) consisting of sheets of Mg-centered octahedra. Brucite is a raw material of commercial importance used for several applications, such as flame retardant and smoke suppression product for insulating materials and coatings, inorganic additive in ceramic inks, pigments and cements, for CO2 sequestration and as MgO source. Brucite is a widespread mineral frequently found in marble as a product of alteration of periclase, or as an accessory mineral in metamorphic limestones and dolomite schists, but more commonly brucite crystalizes during the serpentinization of ultramafic rocks. Given the possible concomitant occurrence of naturally occurring asbestos (NOA) in serpentinites, the presence of brucite in these rocks should arise concern. The most common asbestos type in serpentinites is chrysotile, which is classified by the International Agency for Research on Cancer (IARC) as a human carcinogen. North America, North Europe and China are the largest producers and exporters of this raw material, but no particular precautions are taken as it is considered a safe product. To date, the occurrence of chrysotile in commercial brucite had never been reported. Our study demonstrates that this view must be reconsidered. Through multi-analytic protocol based on morphometric, chemical and mineralogical analyses, we highlighted the evidence of respirable regulated chrysotile (serpentine asbestos) fibers in a commercial brucite currently traded worldwide. The presence of a serpentine phase was evidenced by chemical analyses, X-ray powder diffraction and thermogravimetric-thermodifferential analyses while the occurrence of breathable regulated fibers was confirmed by morphometric observations through scanning electron microscopy. Especially, fibers with length >5 µm, width 3, in a concentration of 169 mg/kg (0.02 wt%) were found. In the light of these findings, we think that brucite-exposed workers should be aware of the potential hazard associated with the use of raw brucite. Therefore, we suggest that an asbestos-free certification should be imposed to the brucite mining companies and distributors, through the implementation of a multidisciplinary protocol or at least by electron microscopy, to rule out the occurrence of asbestos. Similar future studies may affect ‘doubtful’ raw materials commonly marketed, such as diopside, olivine and magnesite.

Today, despite considerable efforts undertaken by the scientific community, the mechanisms of carcinogenesis of mineral fibres remain poorly understood. A crucial role in disclosing the mechanisms of action of mineral fibres is played by in vitro and in vivo models. Such models require experimental design based on negative and positive controls. Commonly used positive controls are amosite and crocidolite UICC standards, while negative controls have not been identified so far. The extensive characterisation and assessment of toxicity/pathogenicity potential carried out in this work indicate that the commercial fibrous wollastonite NYAD G may be considered as a negative standard control for biological and biomedical tests involving mineral fibres. Preliminary in vitro tests suggest that wollastonite NYAD G is not genotoxic. This material is nearly pure and is characterized by very long (46.6 µm), thick (3.74 µm) and non-biodurable fibres with a low content of metals. According to the fibre potential toxicity index (FPTI) model, wollastonite NYAD G is an inert mineral fibre that is expected to exert a low biological response during in vitro/in vivo testing.

Calcium carbonate, silica and calcium phosphate have been selectively used by organisms in the production of mineralized hard parts throughout the Phanerozoic. Among these materials, bioapatite has enabled fundamental acquisitions in the evolution of life. Despite the remarkable biological success, the crystallography of bioapatite and the eventual modification of its lattice parameters over geological time have in contrast been scarcely investigated. In our study, we analyzed living, dead and fossil remains of both vertebrate and invertebrate organisms that biomineralized apatite, ranging from the Cambrian to the Recent, a time interval spanning over 500 million years. We detected in this way the bioapatite crystal features of the major phosphatic phyla (Brachiopoda, Arthropoda, Bryozoa, and Chordata: the latter including conodonts, cartilaginous and bony fishes, amphibians, reptiles, birds and mammals). Groups were investigated using either fossil or recent material (dead and/or alive, the former indicating organisms who died in recent times, the latter referring to material extracted from living organisms). The experimental results revealed that phosphatic materials from living, dead, and fossilized organisms have a distinct crystallographic signature. In fact, bioapatite in fossils is characterized by lower values of the crystal lattice cell parameter a (9.320-9.439 Å compared to 9.355-9.466 Å in dead and alive organisms), whereas the cell parameter c is less variable (6.857-6.911 Å for fossils and 6.861-6.902 Å for recent bioapatite); Student t-tests, applied to the means of these ranges of values (a¯=9.369 Å, c¯=6.887 Å, volume¯=523.6 Å3 for fossil values, a¯=9.415 Å, c¯=6.878 Å, volume¯=528.0 Å3 for recent values), highlighted significant differences between fossils and recent samples at a level p < 0.01 for the three cell parameters. These changes, which begin at the death of the organism and only stabilize in the ultimate stages of fossilization, mirror the isomorphic chemical substitutions within the crystal lattice and drive to a general decrease of the cell volume (i.e., the volume of the bioapatite hexagonal crystalline cell frame) over time, with an average reduction of 4.4 Å3 (0.8%) from alive to fossil organisms.

Conodont elements are calcium phosphate (apatite structure) mineralized remains of the cephalic feeding apparatus of an extinct marine organism. Due to the high affinity of apatite for rare earth elements (REE) and other high field strength elements (HFSE), conodont elements were frequently assumed to be a reliable archive of sea-water composition and changes that had occurred during diagenesis. Likewise, the crystallinity index of bioapatite, i.e., the rate of crystallinity of biologically mediated apatite, should be generally linearly dependent on diagenetic alteration as the greater (and longer) the pressure and temperature to which a crystal is exposed, the greater the resulting crystallinity. In this study, we detected the uptake of HFSE in conodont elements recovered from a single stratigraphic horizon in the Upper Ordovician of Normandy (France). Assuming therefore that all the specimens have undergone an identical diagenetic history, we have assessed whether conodont taxonomy (and morphology) impacts HFSE uptake and crystallinity index. We found that all conodont elements are characterized by a clear diagenetic signature, with minor but significant differences among taxa. These distinctions are evidenced also by the crystallinity index values which show positive correlations with some elements and, accordingly, with diagenesis; however, correlations with the crystallinity index strongly depend on the method adopted for its calculation.

A hydrated complex of 1,10-phenanthroline with Cu2+ cation was intercalated in the interlayer space of montmorillonite. This intercalation occurs initially by through a cation exchange mechanism in which the charge of the complex cation compensates the excess of the negative charge of the interlayer, then, once the cation exchange capacity (CEC) value has been reached, by direct adsorption of the sulfate salt of this complex (i.e. the cation together with its sulfate counterion). This material has showed interesting entrapping properties of gaseous phases and a peculiar chemical reactivity. However, the complete characterization and explanation of the formation of these materials is difficult with only experimental techniques. Hence, we used computational methods at atomic level to know how are the molecular structure of these complexes and their adsorption capacity of ammonia inside the interlayer confined space of montmorillonite for a better understanding of the experimental behaviour. First Principles calculations were performed based on Density Functional Theory (DFT). The intercalation of the phenanthroline-Cu(II) complex inside the nanoconfined interlayer of montmorillonite is energetically favourable in the relative proportion observed experimentally, being a cation exchange process. The further adsorption of the sulfate salt of the phenanthroline-Cu complex is also energetically possible. The adsorption of ammonia molecules in these montmorillonite-phenanthroline-Cu complexes was also favourable according with experimental behaviour.

Cofilins are small protein of the actin depolymerizing family. Actin polymerization/depolymerization is central to a number of critical cellular physiological tasks making cofilin a key protein for several physiological functions of the cell. Cofilin activity is mainly regulated by phosphorylation on serine residue 3 making this post-translational modification key to the regulation of myofilament integrity. In fact, in this form, the protein segregates in myocardial aggregates in human idiopathic dilated cardiomyopathy. Since myofilament network is an early target of oxidative stress we investigated the molecular changes induced by oxidation on cofilin isoforms and their interplay with the protein phosphorylation state to get insight on whether/how those changes may predispose to early protein aggregation. Using different and complementary approaches we characterized the aggregation properties of cofilin-2 and its phosphomimetic variant (S3D) in response to oxidative stress in silico, in vitro and on isolated cardiomyocytes. We found that the phosphorylated (inactive) form of cofilin-2 is mechanistically linked to the formation of an extended network of fibrillar structures induced by oxidative stress via the formation of a disulfide bond between Cys39 and Cys80. Such phosphorylation-dependent effect is likely controlled by changes in the hydrogen bonding network involving Cys39. We found that the sulfide ion inhibits the formation of such structures. This might represent the mechanism for the protective effect of the therapeutic agent Na2S on ischemic injury., Graphical abstract Image 1, Highlights • Cofilin changes the hydrogen bonding network involving Cys39 in its phosphorylated form. • This phosphorylation-dependent effect of oxidation promotes the formation of a disulfide bond between Cys39 and Cys80. • The formation of the Cys39 and Cys80 disulfide bond favors the formation of fibrillar aggregates. • The sulfide ion inhibits the formation of such structures.

Amphinomid fireworms are notorious for their stinging dorsal bristles (notochaetae), but it is still unclear whether the irritation they cause is merely mechanical or if the notochaetae contain toxins. Furthermore, although fireworm chaetae have always been described as calcareous, their composition has never been investigated to date and strong debates are ongoing on their internal structure. Unravelling the native ultrastructure and composition of fireworm chaetae is the first crucial step to assess whether the hypothesis of toxin vehiculation could be fully considered. We examined for the first time the chemical and mineralogical composition, the ultrastructure and the external structure of the dorsal and ventral chaetae of the large species Hermodice carunculata. All the measurements were carried out on samples prepared without the use of chemical reagents, except for those targeted to investigate if decalcification altered the ultrastructure of the chaetae. A crystal-chemical strategy, combining chemical, diffraction and thermal analyses clearly showed the occurrence of crystalline calcium carbonate and clusters of phosphatic amorphous material. Scanning electron micrographs and energy dispersive X-ray measurements showed that the dorsal chaetae have an extremely shallow insertion point in the body respect to the ventral chaetae, that could facilitate the release of the notochaetae in the environment. Their proximal part is characterized by canals with a hexagonal pattern rich in Ca and P, followed by a large cavity upwards. The harpoon-shaped ends and the central canals of the notochaetae completely disappeared after exposure to EDTA. The notochaetae are hollow and may be able to vehicle toxins. The absence of the honeycomb pattern in the distal part of the notochaetae and their slenderness probably contribute to their brittleness and high sensitivity to breakage on contact. These observations constitute keystone understandings to shed light on fireworm defensive and offensive capacities and their ecological success.

The reported data are related to a research paper entitled "Phosphorylated cofilin-2 is more prone to oxidative modifications on Cys39 and favors amyloid fibril formation" [1] . Info about the formation and redox properties of the disulfide bridge of a protein is quite difficult to obtain and only in a few cases was it possible to observe a cyclic voltammetry (CV) signal [ 2 , 3 ]. Human cofilin-2 contains two cysteines (Cys39 and Cys80) which can be oxidized in suitable conditions and form a disulfide bridge [1] . For this purpose, CV measurements were carried out on human cofilin-2 WT and its mutant S3D immobilized on a gold electrode coated by an anionic self-assembled monolayer (SAM), after a pre-oxidation time which was fundamental for observing a CV signal relating to the oxidation/reduction process of the disulfide bridge of the proteins. The data include CV curves obtained with and without electrochemical pre-oxidation and after oxidation with H2O2. In addition, the plot of the cathodic peak current vs. electrochemical pre-oxidation time and the pH dependence of the formal potential (E°’) are reported. The data obtained by CV measurements were used to determine the time required to form the disulfide bridge for the immobilized proteins and, consequently, to observe the CV signal, to calculate the E°’ values and analyse the pH dependence of E°’. The electrochemical data were provided which will be useful for further electrochemical investigations regarding proteins bearing disulfide bridge(s) or cysteines prone to oxidation.

The intercalation of [Cu(Phen)(H2O)2]2+ (CuPhen) in montmorillonite (Mt) produces a stable hybrid material that is very efficient in removing NH3 from gas phase even at extremely low pressures. The process was studied by elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry and DR UV¿Vis, NMR and X-ray absorption spectroscopy. The adsorption of CuPhen on Mt consists of two consecutive steps. During the first one, CuPhen intercalates alone into Mt through a cation exchange process, afterwards CuPhen and SO42¿ ions entry jointly into the mineral interlayer. The two-steps adsorption process is described by a VI-type isotherm, successfully fitted by two independent Frumkin isotherms. NH3 trapping is long-lasting, easy, fast even at extremely low gas pressure and reversible under mild conditions. Mt containing CuPhen always results well performant in removing ammonia from gas phase, but an appreciably higher adsorption capacity of NH3 is obtained when SO42¿ ion is absent from the interlayer. This hybrid montmorillonite is thus a promising material to be used in industrial or environmental contexts, as an efficient air-cleaner., We acknowledge MIUR-PRIN2017 - PROGETTO N. 2017L83S77, the Spanish CRG BM25-SpLine, the Spanish Ministry of Science Innovation and Universities (MICIU), the Spanish National Research Council (CSIC) and The European Synchrotron (The ESRF) for the use of the synchrotron radiation facilities and financial support, the LADAC laboratory of DSCG, University of Modena and Reggio Emilia. A.S. acknowledges the financial support from the Comunidad de Madrid, Spain for an “Atracción de Talento Investigador” contract (No. 2017-t2/IND5395).

This work provides a systematic study of the μ-oxo-di-fac-[triaqua-(1,10-phenanthroline-κ2 N,N′)-iron(III)]bis(sulfate), [(OH2)3(phen)FeOFe(phen)(OH2)3] (SO4)2 (phen = phenanthroline). Crystal structure is determined by single-crystal X-ray diffraction data and refined to R = 0.039. The crystal structure is monoclinic (Z = 2), space group P21 with unit cell dimensions a = 8.5157(3), b = 17.6434(5), c = 9.9678(3) A, β = 90.133(2)°, V = 1497.62(8) A3. The triaqua(1,10-phenanthroline)iron(III) parts are linked through one oxo-bridge. Both Fe(III) cations show a distorted octahedral coordination. The single-crystal data are complemented by computational chemistry modeling at quantum mechanical level, X-ray powder diffraction at room and high temperature conditions and by thermal analysis. Molecular modeling suggests that the role of the crystallization water molecules is critical to establish the intermolecular interactions for the stability of the crystal structure.

In their Commentary to our paper recently published in Zoology (Righi et al., 2021a), Tilic and Bartolomaeus question our findings that the chaetae of Hermodice carunculata (Annelida) are hollow and able to store and deliver venoms. They sustain the idea that inflammatory chemicals are secreted through epidermal glands and possibly exposed to predator trough wounds caused by the brittle chaetae. We provide evidence-based arguments in support of our considerations. The sample preparation procedures did not affect the native inner structure of unfixed fireworm chaetae, which is clearly hollow as supported by both ultrastructure observation and crystal-chemical analysis of constituents. Furthermore, our previous and more recent feeding bioassays and chemical analysis indicate both that chaetae retain strong deterrent capacities even when isolated from the body of H. carunculata, and that they contain venoms. The cellular mechanisms involved in fireworm chaeta storage and deliver of chemicals are still unstudied. We strongly believe that this lack of knowledge should draw further attention on H. carunculata biology, pursuing new hypotheses and studies based on the noteworthy information which has been obtained so far.

Bioapatite represents an important acquisition in the evolution of life, both in the seas and on land. Vertebrates applied calcium-phosphate biominerals to grow their skeletal support and to shape their teeth, while some invertebrates sheltered their soft parts within apatite shells. Conodonts were the first among vertebrates to experiment with skeletal biomineralization of tooth-like elements in their feeding apparatus. Spanning a time record of over 300 million years, they offer a unique tool to test possible variation in bioapatite structure from the experimentation of a very primitive biomineralization type to a more evolute pattern just before going extinct. X-ray microdiffraction carried out through an X-ray micro-diffractometer, integrated with environmental scanning electron microscopy coupled with chemical microanalyses (ESEM-EDX), has been applied in this study to investigate conodont element crystal structure throughout the entire stratigraphic range of these organisms. In particular, bioapatite crystallographic cell parameters have been calculated for about one hundred conodont elements ranging from the late Cambrian to the Late Triassic. Resulting data clearly indicate two distinct distribution plots of cell parameters for paraconodonts and euconodonts. In contrast, age, taxonomy, geographic provenance and CAI do not affect the dimension of the bioapatite crystal cells. Conodont bioapatite crystallographic cell parameters have been compared with cell parameters resulting from phosphatic/phosphatized material (ostracodes, brachiopods, bryozoans, and fish teeth) present in the same residues producing conodonts. Resulting values of the cell parameters are, in general, mainly correlated with the type of organisms even if, for some of them, a correlation also with age cannot be completely ruled out. According to our data, primary bioapatite appears to imprint a key signature on fossil crystal-chemistry (crystal structure and major chemical element contents), while the contribution of fossilization and diagenetic processes seems less relevant.

The interaction of volatile organic sulfur derivatives, such as 1-heptanethiol (C7H16S), with clay minerals treated with a μ-oxo Fe3+-phenanthroline 1:1 complex results strongly affected by crystal chemical properties of pristine mineral phases. In particular, two sepiolite clays with different structural features demonstrated significantly different ability to immobilize the Fe3+-phenanthroline complex at two pH values (pH = 5.4 and pH = 2.3). The most effective binding was obtained with sepiolite with higher structural disorder at pH 5.4. Accordingly, the resulting hybrid material showed also the greatest efficiency in removal of thiol in gas phase. A direct correlation can be established between the adsorption of the Fe3+-phenanthroline complex and the gas binding process at room temperature. In fact, 1-heptanethiol entrapping occurs via redox reactions between Fe3+ and a first thiol molecule to give the reduced Fe2+-phenanthroline complex and disulfide, followed by the binding of further thiols to the reduced metal centre. The extremely high amount of thiol immobilized by the hybrid material also suggests the co-presence of a catalytic mechanism that guarantees the reoxidation of Fe+2 to Fe+3 and the restoration of redox reactions with thiol. Investigation and conclusions were supported by the several experimental techniques: elemental analysis, X-ray powder diffraction analyses, UV–Vis measurements, FT-IR and NMR spectroscopies, thermogravimetric analyses.

Six Fe-bearing mica samples with different Fe ordering, Fe 2+ /(Fe 2+ +Fe 3+ ) ratio, octahedral, and tetrahedral composition were studied. Four micas belong to the phlogopite-annite join (space group C 2/ m ), two are Mg-rich annite and two are Fe-rich phlogopite, one is a tetra-ferriphlogopite (space group C 2/ m ) and one is Li-rich siderophyllite (space group C 2). Thus these samples had a different environment around the Fe cations and layer symmetry. These micas were characterized by chemical analyses, single-crystal X-ray diffraction, X-ray absorption spectroscopy, and magnetic measurements. In samples with Fe mostly in octahedral coordination, dominant magnetic interactions among Fe atoms are ferromagnetic, which reach a maximum at higher Fe 2+ /(Fe 2+ +Fe 3+ ) ratios. Samples with higher Fe 2+ /(Fe 2+ +Fe 3+ ) ratio are also characterized by higher values of the Curie-Weiss θ constant. Where Fe 2+ /(Fe 2+ +Fe 3+ ) ratios decrease, θ values also decrease. The Fe 3+ -rich phlogopite shows predominant Fe 3+ in tetrahedral coordination and shows anti-ferromagnetic interactions with a negative value of the Curie-Weiss θ constant (i.e., θ = −25 K). Fe ordering in octahedral trans - and in one of the two cis -sites accounts for a greater θ value in Li-rich siderophyllite when compared to other samples showing similar octahedral Fe content. Our data suggest that Fe 3+ cations and other non-ferromagnetic cations hinder long range magnetic ordering. This observation may produce for the different role of octahedral Fe magnetic interactions that can in principle develop along long Fe-rich octahedral chains, when compared to tetrahedral-octahedral interactions that are confined within the layer by the non-ferromagnetic cations of the interlayer. Spin glass behavior is indicated by the dependency of the temperature to produce maxima in the susceptibility curve. These maxima are related to the frequency of the applied AC magnetic field.

Recent biomedical applications of clay materials have included organically modified clays or clay minerals with the purpose of modifying and improving drug biological activity. The present research aims to explore the potential benefits provided by a raw bentonite (Bt) modified by gentamicin (GM) adsorbed within montmorillonite interlayers in the management of cutaneous infectious diseases. Information arisen from controlled X-ray powder diffraction, thermogravimetry coupled with evolved gas mass spectrometry, and molecular dynamics simulations pointed out GM monolayer arrangement within montmorillonite framework without producing substantial effects on the layer periodicity. Concerning skin biomedical application, unlike the pure antibiotic permeating along the trans-follicular pathway across stratum corneum, the organo-modified Bt/GM would favor the trans-epidermal route along inter-cluster corneocyte region, as in vivo skin penetration studies by means of tape stripping test indicated. Based on the results obtained, GM intercalation could represent a potential advantageous approach allowing a long-term Bt/GM reservoir for sustained antibacterial activity.

A stable hybrid material (Mt-Fe(III)Phen) formed by intercalation of the μ-oxo Fe(III)-phenanthroline complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]4+ (Fe(III)Phen) in montmorillonite (Mt) is able to immobilize H2S in gaseous phase with high efficiency even at extremely low pressures. DR UV–vis and I.R. spectroscopies, elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry, and X-ray absorption spectroscopy show that the material has high adsorption capacity, performs fast H2S trapping and is long-lasting. Moreover, even extremely low levels of H2S can be removed easily and quickly from gaseous phase using a suitable amount of the trapping material. The immobilization mechanism likely involves a redox reaction between iron (III) and one S2− ion, followed by the binding of a second S2− ion to the metal centre. The process takes place at room temperature, is reversible for several cycles, and does not require pre-treatment of neither gaseous H2S nor the adsorbent material. Therefore, this modified montmorillonite is a promising material to get rid of H2S in processes of environmental interest and to obtain gaseous (and gasifiable) high quality hydrocarbons in fuels refineries.

The intercalation of the μ-oxo Fe(III)-phenanthroline 1:1 complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]+4 inside montmorillonite yielded a nanostructured material with strong and selective entrapping ability toward thiol molecules and hydrogen sulfide. In this work, experiments and computational molecular modeling by means of quantum mechanical calculations has been applied to study the molecular structure and interactions between this complex and the interlayer of montmorillonite. This approach allowed the identification of the geometrical disposition of the complexes inside the interlayer, the characterization of the hydration and coordination water molecules, and the explanation of the physico-chemical properties of these functionalized materials. The antiferromagnetic spin configuration of the Fe(III) ions results in the most stable state. Two conformers of the complex have been considered, having the phenanthroline rings in twisted or in parallel planes, respectively, and the transition of one conformer in...

Using saturated or enriched zeolites as slow release fertilizers (SRFs) is considered as an environmental-friendly strategy to enhance use of macronutrients in sandy soils. In this paper, two natural zeolites, clinoptilolite (CLI) and chabazite (CHA) were used as mineral precursors to prepare NH₄⁺/K⁺ saturated clinoptilolite (NH₄⁺/K⁺-CLI) and chabazite (NH₄⁺/K⁺-CHA) as zeolitic nutrient sources (ZNSs). Comparison between the nutrient retention capabilities of these ZNSs was one of the main objectives of this study. The NH₄⁺/K⁺-CLI and NH₄⁺/K⁺-CHA were prepared by soaking the zeolites in NH₄Cl and KCl solutions, respectively. Leaching tests were performed on a sandy soil amended with chemical fertilizers (CFs), NH₄⁺/K⁺-CLI and NH₄⁺/K⁺-CHA to evaluate the leaching properties of them. The results indicated that approximately 84% and 88% of the NH₄⁺ and K⁺ of soils fertilized with CFs were lost during the experiment, respectively. While, the NH₄⁺ and K⁺ losses from soils amended with NH₄⁺/K⁺-CLI and NH₄⁺/K⁺-CHA were 29%, 23%, and 14%, 24%, respectively. Despite of drastic changes in leaching behavior of CFs, nutrient losses from ZNSs were more uniform during the experiments. No significant difference was found between the two studied zeolites on reduction of K⁺ loss. However, CHA was more effective in preventing NH₄⁺ loss during leaching.

The directives of the European Commission Environment on the management of hazardous asbestos-containing materials (ACM) are pointing towards treatment and recycling other than disposal in landfills. KRY·AS is a secondary raw material obtained by the thermal transformation of cement-asbestos (CA) and can be inserted in the production line of e.g. concrete, clay bricks, ceramics, and plastic materials. This being a possible future solution to the huge “CA-emergency” in Italy, additional recycling options are sought. In this work, KRY·AS was used for the production of glass-ceramic frits destined for the manufacturing of porcelain stoneware slabs. Two novel frits were obtained by vitrifying KRY·AS together with minor amounts of natural raw materials as well as glass waste. The resulting frits were added in a ceramic body formulation (0, 1, 3, 5 wt.%). Phase composition, microstructure and technological properties of fired samples were evaluated and the results were compared to those obtained when using a standard commercial frit. According to water absorption tests, the novel products can be classified as BIa-type. Comparable or even improved technological properties were found between the standard body and the frit-bearing ones. More precisely, the addition of 5 wt.% of the novel frits led to better stain resistance as well as higher productivity due to reduction of the linear firing shrinkage. Improved mechanical strength (ca. 75 MPa compared to ca 60 MPa for the standard) was also obtained. The novel recycling route of KRY·AS supports a conclusive solution for the management of hazardous CA in Italy.

Removal of highly toxic H2S for pollution control and operational safety is a pressing need. For this purpose, a montmorillonite intercalated with Cu(II)-phenanthroline complex [Cu[(Phen)(H2O)2]2+ (Mt-CuPhen) was prepared to capture gaseous H2S under mild conditions. This hybrid material was simple to obtain and demonstrated an outstanding ability to entrap H2S at room temperature, retaining high efficiency for a very long time (up to 36.8 g of S/100 g Mt-CuPhen after 3 months of exposure). Sorbent and H2S uptake were investigated by elemental analysis, X-ray powder diffraction measurements, diffuse reflectance (DR) UV&ndash, Vis and infrared spectroscopy, thermal analysis and evolved gas mass spectrometry, scanning electron microscopy equipped with energy-dispersive X-ray spectrometer, and X-ray absorption spectroscopy. The H2S capture was studied over time and a mechanism of action was proposed. The entrapping involves a catalytic mechanism in which [Cu[(Phen)(H2O)2]2+ acts as catalyst for H2S oxidation to S0 by atmospheric oxygen. The low cost and the long-lasting performance for H2S removal render Mt-CuPhen an extremely appealing trap for H2S removal and a promising material for many technological applications.

Rossiantonite, ideally Al3(PO4)(SO4)2(OH)2(H2O)10·4H2O, triclinic (space group P 1), a = 10.3410(5), b = 10.9600(5), c = 11.1446(5) A, α = 86.985(2), β = 65.727(2), γ = 75.064(2)°, V = 1110.5(1) A3, Z = 2, is a new mineral from the Akopan-Dal Cin cave system in the Chimanta massif (Guyana Shield, Venezuela). The mineral occurs as small (≤0.15 mm) and transparent crystals in a white to slightly pink fine-grained sand, filling spaces between boulders of weathered quartz sandstone. Associated phases are gypsum, sanjuanite, rare alunite, quartz and micro-spherules of amorphous silica. Rossiantonite is colorless with a white streak and vitreous luster. The mineral is brittle with irregular to sub-conchoidal fracture and it shows a poorly developed cleavage. Rossiantonite is biaxial and not pleochroic, with mean refractive index of 1.504. The calculated density is 1.958 g/cm3. Electron microprobe analyses, with H2O measured by thermogravimetric analysis, provided the following empirical formula based on 28 O apfu: Al2.96Fe0.03P1.01S2H30.02O28. The five strongest lines in the X-ray powder diffraction pattern, expressed as d (A), I , ( hkl ) are: 4.647, 100, (210); 9.12, 56, (100); 4.006, 53, (220); 8.02, 40, (110); 7.12, 33, (011). The crystal structure, refined using 3550 unique reflections to R = 0.0292, is built of PO4 and Al O6 polyhedral rings, creating complex chains parallel b by sharing the OH-OH edge belonging to the Al(3) polyhedron. Three symmetrically independent Al sites can be identified, namely: Al(1), Al(2), and Al(3). Tetrahedral sites, occupied by P, share all their apexes with AlO6 octahedra. Unshared octahedral apexes are occupied by water molecules. Four additional water molecules are placed in between the previously identified chains. Two oxygen tetrahedra, occupied by S atoms, are connected along the chains by means of weak hydrogen bonding. The rossiantonite structure shows similarities with minerals belonging to the sanjuanite-destinezite group.

The interaction of an efficient deflocculant, sodium hexametaphosphate (NaHMP), with illite and montmorillonite (Mt) samples of different origins was investigated analyzing the HMP uptake (adsorption on mineral surface and/or intercalation inside the interlayer space) and the ion release mechanisms. HMP adsorption isotherms on a standard Na-saturated illite were determined at different temperatures which yielded the thermodynamic parameters of the process and the maximum adsorbed amount of the ion on this mineral. The data indicate that the adsorption process is hindered with respect to that on kaolinite and is consistent with adsorption of HMP on the aluminol edge sites, forming Al–O–P linkages. The effect of HMP on the natural illite and Mt samples was analyzed using different techniques. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to detect the concentration of P, Si, Al, Ca, Mg and K in deflocculant solutions wetting the clay minerals in order to identify the immobilization, dissolution and exchange reactions associated to the deflocculant activity. Thermal analysis and XRD measurements were used to gain information on the properties of the HMP-treated clay minerals. The peculiar ability of Mt samples to immobilize HMP is proposed to be due to intercalation processes involving the formation of Ca2 +/HMP complexes inside the interlayer space. These processes could be responsible of the well known decrease in the deflocculant efficiency of HMP in ceramic slurries rich in Mt.

Scientific Reports 6: Article number: 35865; published online: 24 October 2016; updated: 19 January 2017. The Author Contributions statement in this Article is incomplete: F.B., D.M., M.P., L.L., F.d.M. and E.C. acquired and analyzed the data; C.A.B., G.D.R., M.F.B. and M.B. provided critical input to the analyzed data and to the manuscript; R.

The μ-oxo Fe(III)-phenanthroline complex [(OH)(Phen)FeOFe(Phen) (OH)] intercalated in montmorillonite provides a stable hybrid material. In this study, the ability and efficiency of this material to immobilize thiols in gas phase, acting as a trap at the solid-gas interface, were investigated. Aliphatic thiols containing both hydrophilic and hydrophobic end groups were chosen to test the selectivity of this gas trap. DR-UV-vis, IR, elemental analysis, thermal analysis and evolved gas mass spectrometry, X-ray powder diffraction, and X-ray absorption spectroscopy techniques were employed to characterize the hybrid material before and after thiol exposure and to provide information on the entrapping process. Thiol immobilization is very large, up to 21% w/w for heptanethiol. In addition, evidence was obtained that immobilization occurs through the formation of a covalent bond between the iron of the complex and the sulfur of the thiol. This provides an immobilization process characterized by a higher stability with respect to the methods based on physi-adsorption. Thiol immobilization resulted thermally reversible at least for 20 adsorption/desorption cycles. Unlike standard desulfurization processes like hydrotreating and catalytic oxidation which work at high temperatures and pressures, the present system is able to efficiently trap thiols at room temperature and pressure, thus saving energy. Furthermore, we found that the selectivity of thiol immobilization can be tuned acting on the amount of complex intercalated in montmorillonite. In particular, montmorillonite semisaturated with the complex captures both hydrophobic and hydrophilic thiols, while the saturated montmorillonite shows a strong selectivity toward the hydrophobic molecules.

Calcium phosphate minerals are frequently used in recent and fossil organisms, from unicellular to vertebrates. Apatite minerals offer in fact a wide range of biological adaptability in order to fulfil different uses, from protection to attack, from skeletal support to food grasping and processing. In addition, microbes are thought to play an active role in apatite precipitation. However, the term "bioapatite" has often been used improperly in the past to indicate apatite mediated by the intervention of organisms. Although development of mineralized parts seems controlled by specifically produced organic molecules that remain entrapped within the mineral units, the growth mechanisms and the diagenetic evolution of apatite fossils are still poorly understood. Conodonts represent an extinct group of jawless vertebrates that were the first among the group to experiment skeletal biomineralization with apatite elements in their feeding apparatus. We have recently applied microdiffraction techniques to conodont structural characterization on an Upper Ordovician (A. ordovicicus Zone) conodont fauna from Normandy (France). The conodont elements had a CAI of 4-5, indicating a heating up to 400°C, and were characterized by diagenetic neo-crystals arranged on the surface in distinctive large columnar, blocky or web-like microtextures. By the integration of ?XRD and chemical analyses, we have revealed that diagenetic apatite neo-crystals exhibit the same chemical composition as the original fossil structure, and that no significant difference in unit cell parameters appears to exist between the newly formed apatite crystals and those of the smooth (with no crystal overgrowth) conodont surfaces. In order to better constrain variability of apatite cell parameters, the analysis has been extended to encompass conodont elements of different age and having diverse CAI as well as apatites documented in other fossil and living organisms. Apatite crystals were analyzed in terms of size, morphology, composition, geometry and spatial arrangement by integration of optical and scanning electron microscopy (SEM), environmental scanning electron microscopy coupled with chemical microanalyses (ESEM-EDX), RAMAN analysis, and X-ray microdiffraction (?XRD). In particular, the microdiffraction method proved to be a reliable tool in describing mineralogical features that otherwise cannot be resolved by the use of microscopic methods alone. Microdiffraction measurements were carried out using collimators with different beam diameters. ?XRD method allows for small volumes of material to be probed: X-rays are collimated to form a small beam before irradiating a sample, giving the possibility to check for local "micro" environment such as defects or preferred orientations of the crystallites.

International audience; The incorporation rate of Zn into the calcareous tests of Pseudotriloculina rotunda was investigated in culture in order to evaluate the possibility of using Zn/Ca ratios as a pollution proxy. Foraminifera were incubated at zinc concentrations up to 10-fold higher than unpolluted seawater (sea+10mg Zn/L) during 70days. New calcite was investigated under the Environmental Scanning Electron Microscope (ESEM), for potential alteration of test structure. Laser ablation-Inductively Coupled Plasma-Mass spectrometry (LA-ICP-MS) was used to quantify Zn contents. The analyses revealed that test structure is not visibly altered by the presence of zinc. However, significant Zn incorporation is detected by the LA-ICP-MS. The zinc partition coefficient, DZn, decreases at increasing Zn concentrations (from 4.03±0.06 to 0.2±0.01) and the zinc is incorporated into the calcite not necessarily linearly.

This paper, after an introduction about the state of the art in the methods for the evaluation of Hg chemical speciation, focuses on Hg polluted soils and sediments from Siele mining area (Piancastagnaio, Siena, Italy). In particular, the mineralogical composition was evaluated via X-ray powder diffraction, total Hg was determined via inductively coupled plasma optical emis- sion spectroscopy on acid digested samples, and Hg binding forms were investigated both via sequential selective extraction and pyrolytic extraction. Solutions obtained via sequential selective extraction were checked for Hg content using inductively coupled plasma optical emission spectroscopy, whereas to carry out pyrolytic extraction a thermogravimetric analyser coupled with an evolved gas mass spectrometer was used. To our knowledge, this last method was never used for this purpose on natural samples. Experimental results enhance that: i) Hg detection via thermal analyses can qualitatively distinguish among different Hg com- pounds. ii) The temperature of Hg thermal release is affected by both the sample matrix and the Hg bond type. iii) Thermal analyses fail in the attempt of a quantitative determination of the evolved species; this goal is better achieved via the selective chemical leach- ing. iv) Most of the Hg is related to HgS-like bonds, thus pointing to the presence of very stable Hg compounds. v) Only in some samples we found also organo-complexed Hg-like compounds and, in a limited amount, hydrosoluble Hg and/or Hg species soluble in weakly acid environment. vi) No correlation between sampling point and both total Hg and/or Hg speciation was observed.

This study describes the influence of temperature on two Hg(II)-cysteine modified clay minerals with different layer charges (i.e., montmorillonite and vermiculite) by using chemical and thermal analyses coupled with evolved gas mass spectrometry (TGA-MSEGA), synchrotron-based X-ray absorption spectroscopy (XAS), and X-ray powder diffraction (XRPD) techniques; these two latter techniques were applied on samples heated "in situ" up to 900 degrees C. Hg bonds cysteine by the thiol group with Hg-SH bond lengths similar in both clay minerals, thus suggesting their independence from layer charge. On the contrary, the thermal behaviour of the adsorbed organometallic complexes was strictly layer charge dependent, as evidenced by decomposition temperatures, which were lower in montmorillonite than in vermiculite. Results from X-ray absorption near edge structure (XANES) spectroscopy evidenced nearly complete Hg desorption in montmorillonite between 600 and 700 degrees C, unlike in vermiculite where Hg was still present at these values. (C) 2010 Published by Elsevier B.V.