Electron Microscopy-energy Dispersive Spectroscopy Research Articles

Evaluation of the Relationship between the Milling Breakage Parameters and Mineralogical Data: A Case Study of Three Copper Ores from a Multi-Mineralised Deposit

The study evaluated the milling kinetics of three copper ores, from a multi-mineralised deposit, which were identified as sulphide 1 (with bornite as a dominant copper mineral), sulphide 2 (mainly composed of chalcopyrite) and oxide (with malachite as a dominant copper mineral) and related the breakage parameters to the mineral composition data. Five mono-size fractions between 1000 µm and 212 µm were dry milled for short grinding times in the laboratory ball mill in order to obtain data for predicting breakage rate parameters. The analytical and mineralogical characterisation of the ores were performed using X-ray fluorescence (XRF) analysis, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, optical microscopy analysis and X-ray diffractometer (XRD). The mineralogy data showed that quartz was the abundant gangue mineral (average for each ore was above 60% (w/w)), followed by K-feldspar minerals (orthoclase and microcline) which constituted between 4% (w/w) and 6% (w/w) and the remainder are the minor calcite and dolomite minerals which are also in the host rock. The experimental milling kinetics parameters and mineralogical data were used to assess the robustness of the heterogeneous (two-component) and homogeneous (single-component) first-order rate breakage models. The mineral composition data were used for setting up the predictions of breakage parameters in the two-component and single-component first-order breakage models. The experimental data fitted better on the two-component breakage model than the single-component breakage model. These results highlighted the influence of two groups of minerals (generally classed as valuable and gangue minerals). The breakage data showed that the selection function for the hard component (the gangue minerals) has a dominant contribution to the overall selection function of the ores, with SiA correlating fairly well with experimental Si. The parameter a in the Austin empirical breakage model was relatively similar (approximately 1) for all three ores, which confirms similar milling conditions to which the ores were subjected to. The data suggests that there is a relationship between breakage parameter α (material-specific parameter) in the Austin empirical breakage model and brittleness index βi (calculated from the mineralogical composition of the gangue phase). No clear trends could be deduced from the cumulative breakage distributions of the three ores. This highlights the complexity of developing relationships between the mineralogical composition data and breakage distributions of the ores which are extracted from the same deposit and with comparable gangue composition.

Casein phosphopeptide-calcium chelate: Preparation, calcium holding capacity and simulated digestion in vitro

In this work, CPP-Ca chelate was synthesized by chelating casein phosphopeptide (CPP) and calcium and characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The antioxidant activity and calcium holding capacity of CPP-Ca were evaluated and its secondary structure transition was monitored during gastrointestinal digestion by in situ Raman spectroscopy. The results demonstrated that calcium chelating rate reached 40 % and calcium ion was bound to CPP mainly through the interaction of carboxyl and amino groups. The result of calcium holding capacity confirmed the formation of calcium phosphate precipitates could be delayed by 10–15 min with increasing CPP concentration. In vitro simulated digestion revealed CPP-Ca exhibited excellent calcium solubility and its secondary structural changes occurred, especially α-helix and β-sheet content. These findings provided significant insights into enhancing bioavailability of calcium supplements and developing of calcium functional foods for human and animals.

Visible light-Fenton degradation of tetracycline hydrochloride over oxygen-vacancy-rich LaFeO3/polystyrene: Mechanism and degradation pathways

In this study, the oxygen–vacancy–rich (OV) lanthanum ferrite (LaFeO3) perovskite (also called LFO) was successfully prepared by an ultrasound–assisted sol–gel method and hydrothermally loaded onto polystyrene (PS) to obtain LaFeO3/polystyrene–oxygen–vacancies (LFO/PS–OVs). The structure and properties of LFO/PS–OVs were investigated using scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), X–ray photo–electron spectroscopy (XPS), photoluminescence spectra (PL) and other characterization methods. The authors also investigated the effects of hydrogen peroxide (H2O2) concentration, catalyst dosage, solution concentration, pH and inorganic anions on the tetracycline hydrochloride (TC) removal efficiency. According to the results, the ultrasonic cavitation treatment and the composite reaction significantly increased the specific surface area of LFO as well as the content of oxygen vacancies and broadened the forbidden band width of LFO. The significant improvement in catalytic activity can be attributed to solving the agglomeration problem of powdered LFO and the introduction of a large amount of OVs. The degradation mechanism was proposed according to the free radical capture experiments and the electron spin resonance (ESR) tests. Based on the DFT calculations and identification of intermediates by LC/MS, the main degradation pathways of TC were proposed. The results showed that reactive oxygen species (ROS) may preferentially attack atoms with the high f0 values of Fukui index. This study gives an insight into the promising application of oxygen–vacancy–rich perovskite/polystyrene composites in environmental remediation.

Ecotoxicity Study of New Composite Materials Based on Epoxy Matrix DER-331 Filled with Biocides Used for Industrial Applications.

The impact of fillers in the epoxy oligomer on the test culture of the marine ecosystem was investigated. The content of additive—biocides—was selected based on the complex research using STAT-GRAPHICS® Centurion XVI. The ecotoxicity of composite surfaces was determined in model systems using methods which are standard in eco-microbiology. The microorganism was identified by studying morphological, cultural, biochemical, and antigenic properties. Studies of the structure and the microrelief of the surfaces of composite materials were conducted using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy. Based on comprehensive research, it was established that the composition of oxytetracycline with content of q = 1.5 wt% and nanosilver with a content of q = 0.075 wt% per 100 wt% of the DER-331 oligomer and 10 parts by the mass of the TETA hardener ensures the formation of a porous nano-heterogeneous structure of the coating, which leads to the acceleration of the release of silver ions from the surface of the polymer. The rational content of the complex additives of biocides ensures adhesion to the cell wall of bacteria with subsequent penetration into it and subsequent change to the cell membrane, its death, and, therefore, the suppression of the fouling process of metal structures.

Microstructural Characterization of ITZ in Copper Slag Concrete Composite

The use of copper slag as an alternative to natural fine aggregates in concrete construction has two advantages: effective management of hazardous waste and assistance in conserving natural resources. In order to build confidence among stakeholders and to improve the utilization of copper slag in concrete construction to the required extent, this article evaluates the interfacial transition zone (ITZ) of hardened copper slag concrete composites through various experimental studies. This includes tests on compressive and split-tensile strengths, sorptivity, microhardness, and microcrack properties of ITZ. This paper also examines the surface morphology of ITZ along with its elementary compositions using field emission scanning electron microscopy (FESEM) imaging and energy dispersion spectroscopy (EDS) analysis. The results show that copper slag improves the ITZ characteristics of hardened concrete due to its higher level of pozzolanic reactivity compared to natural sand.

A Novel Electrochemical Strategy for Chloramphenicol Detection in a Water Environment Based on Silver Nanoparticles and Thiophene

As a synthetic broad-spectrum antibiotic, chloramphenicol (CAP) is widely used in the prevention and treatment of bacterial diseases in aquaculture and animal husbandry, which might lead to severe water contamination and thus threaten our health. Herein, a novel electrochemical strategy for CAP detection is proposed that the sensor was successfully constructed based on the hardly mentioned anodic peak (about −0.56 V) by modifying silver nanoparticles (AgNPs) and thiophene (TP) on a glassy carbon electrode (GCE) as synergistic amplification unit with a simple step-by-step electrodeposition technique. Electrochemical methods, scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS) were applied to characterize the as-prepared sensor. The TP/AgNPs/GCE sensor was used for CAP detection by DPV in the concentration range of 100.0 − 1600.0 μM, the limit of detection (LOD) was 33.0 μM, and the sensitivity was 0.290 μA·μM−1·cm−2. In addition, the sensor has the advantages of simple preparation, low cost, good repeatability, stability and anti-interference. It has been used for the detection of CAP in lake water with a recovery of 101.80–104.85%, and the relative standard deviation (RSD) was lower than 1.22%, which confirms that the sensor has good practicability.

Influence of the fluorine ion content on luminescence properties of the EuII+/III+-doped silicate-substituted apatite

In this study the preparation, characterization, and photoluminescence properties of the Eu3+-doped apatite compounds have been presented. The Eu3+ ion doped silicate-substituted apatite, Ca9.9Eu0.1(PO4)2(SiO4)4(OH)2−xFx where x = 0; 0.8; 1.2; 2.0, was obtained by a microwave-assisted hydrothermal method. A detailed investigation on the heat-treated samples was done by using X-ray diffraction (XRD), scanning electron microscopy energy-dispersive spectrometry (SEM-EDS), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FT-IR). The luminescence behavior of Eu3+ ion was explored based on excitation and emission spectra as well as luminescence decay profiles. The emission spectra under excitation to the charge-transfer (CT) transition shows the broad band associated with Eu2+ ion emission. The asymmetry parameter (R parameter) and CIE color coordinates were also discussed.

Thermal upgrading of nickel from limonite by means of selective reduction

X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy energy dispersion spectroscopy (SEM–EDS), and differential thermal analysis (DTA) measurements were used to investigate the mineralogical characteristics and distribution of data set in limonite soil from Indonesia. The findings point to a complicated inner core in laterite ore. Ni, Fe, Mg, Al, and Si levels in limonite are 1.4, 50.5, 1.81, 4.86 and 16.5 wt %, respectively. The iron oxide/oxyhydroxide content of limonite is 94.4 and 5.6 % silicate. DTA shows that limonite has a phase transition in the low temperature (200 – 300 °C) with the goethite transformation to hematite. This phase is good optimalization for nickel diffusion in the iron. Moreover, for this limonite, the thermal upgrading was used as a good method.

Alkali−Silica Activity and Inhibition Measures of Concrete Aggregate in Northwest China

The alkali−silica reaction (ASR)-induced expansion of mortar bars containing four types of aggregates originating from different regions in northwest China was studied. The chemical composition, mineral composition, vitreous and amorphous substances, and expansion rates were determined using X-ray fluorescence, X-ray diffraction, polarizing microscope images, and the accelerated mortar bar test (AMBT). The inhibitory effects of fly ash and silica fume on the aggregate activity were evaluated. The binary mortar mixes were produced and tested, containing cement and fly ash or silica fume as the partial cement replacement. The microstructure and composition of the ASR products were analyzed by scanning electron microscope energy dispersive spectroscopy (SEM–EDS). The results show that all four types of aggregates exhibited an alkali activity, and that all expansion rates on the 14th day were higher than the standard of 0.1%. The lowest and highest values were 0.2% and 0.3%, respectively. The primary constituent in the chemical compositions of these aggregates was found to be silica. Polarization microscopy also confirmed that they contained alkali-active cryptolites. Fly ash and silica fume could both inhibit alkali activity expansion and the silica fume exhibited a superior inhibition effect. When the fly ash and silica fume contents were 20% and 10%, respectively, the expansion rates of the mortar bar on the 14th day were all less than 0.03%.

Enhanced Energetic Performance of Aluminum Nanoparticles by Plasma Deposition of Perfluorinated Nanofilms.

The performance of Al as nanoenergetic material in solid fuel propulsion or additive in liquid fuels is limited by the presence of the native oxide layer at the surface, which represents a significant weight fraction, does not contribute to heat release during oxidation, and acts as a diffusion barrier to Al oxidation. We develop an efficient technique in which the oxide layer is effectively turned into an energetic component via a reaction with fluorine that is coated in the form of a fluorocarbon nanofilm on the Al surface by plasma-enhanced chemical vapor deposition. Perfluorodecalin vapors are introduced in a low-pressure plasma reactor to produce nanofilms on the surface of Al nanoparticles, whose thickness is controlled with nanolevel precision as demonstrated by high-resolution transmission electron microscopy images. Coated particles show superior heat release, with a maximum enhancement of 50% at a thickness of 10 nm. This significant improvement is attributed to the chemical interaction between Al2O3 and F to form AlF3, which removes the oxide barrier via an exothermic reaction and contributes to the amount of heat released during thermal oxidation. The chemistry and mechanism of the enhancement effect of the plasma nanofilms are explained with the help of X-ray photoelectron spectroscopy, X-ray diffraction, high-angle annular dark-field scanning transmission electron microscopy-energy dispersive spectroscopy, thermogravimetric analysis, and differential scanning calorimetry.

Influence of Dissolved Hydrogen Concentration on the Protective Property of Oxide Film of Alloy 600 Against Primary Water Stress Corrosion Cracking

Primary water stress corrosion cracking (PWSCC) of Alloy 600 has been a key issue in the field of nuclear energy. It is well known that dissolved hydrogen (DH) plays a crucial role in PWSCC initiation, and some studies showed that PWSCC initiation could be mitigated by decreasing the DH concentration. However, there is no consensus on the mechanism of the PWSCC mitigation in a low DH environment. Hence, to reveal the protective property of the passive film formed in various levels of DH, we analyzed the oxide film formed in simulated primary water at 345°C with the DH concentrations of 5 cc/kg and 30 cc/kg-H2O by electrochemical measurements (electrochemical impedance spectroscopy and Mott-Schottky test) and transmission electron microscopy (energy dispersive x-ray spectroscopy and electron energy loss spectroscopy) where the specimens of interest were tested by reverse U bend (RUB) tests, and it was confirmed that the PWSCC initiation time was longer for 5 cc/kg-H2O DH than for 30 cc/kg-H2O DH. Electrochemical measurements showed that the oxide film for the lower DH environment (5 cc/kg-H2O) had a higher electrical resistance and lower defect density than those for the higher DH (30 cc/kg- H2O). The microscopic observation indicated that the intergranular oxidation was relatively insignificant in the lower DH environment. The oxide film for both DH conditions consisted of outer oxides and inner Cr-rich barrier layer. The inner layer for 5 cc/kg-H2O DH had a higher concentration of Fe and a greater ratio of Fe3+/Fe2+ than that for 30 cc/kg-H2O DH. The results suggested that Fe3+ contributed to the formation of a less defective spinel-type structure in the inner oxide in the lower DH environment and thereby provided the alloy surface with corrosion protection. This protective oxide film prevented intergranular oxidation and led to the mitigation of PWSCC initiation in a low DH environment.

Functionalized nano-SiO2 for improving the cycling stability of 4.6V high voltage LiCoO2 cathodes

In order to elevate the high voltage resistance and stability of LiCoO2 cathodes, its application potentialis further excavated. In this paper, the functionalization of nano SiO2(PDA@SiO2) was realized by using the self polymerization coating characteristics of dopamine. Its functionalization with the fumed SiO2 nano-particle center allows even 2% PDA@SiO2 to be uniformly coated onto a LiCoO2 cathode via rotary steaming. It is demonstrated by scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS) that the functional nano-coating is distributed homogeneously on the surface of LiCoO2 particles. The close interaction between nano PDA@SiO2 coating and LiCoO2 particles is emerged, which avoids the agglomeration of nano SiO2 and enhances the function of solid superacid formed by fumed SiO2. The X-ray photoelectron spectroscopy (XPS) shows that less undesired side products are deposited on the surface of LiCoO2, and X-ray diffraction (XRD) and SEM indicate that the lattice expansion and irreversible phase transformation of crystal structure are effectively inhibited. The interface stability and ionic conductivity of LiCoO2 cathodes at high voltage are elevated substantially. Thus, the cycle stability of LiCoO2 cathodes during charge and discharge at 4.6 V high voltage is significantly improved. At room temperature, the modified LiCoO2 cathode with functionalized nano-SiO2 achieved a reversible capacity of around 190 mAh g−1 with the capacity retention of 78% after 200 cycles at 1C, along with a relatively high cyclability of 68% capacity retention after 100 cycles at 1C and 50°C.

Effect of Dolomite Addition on the Structure and Properties of Multicomponent Amphibolite Glasses.

The structure and properties of the glass can be modified by introducing appropriate additives. Dolomite is one of the primary raw materials modifying the properties of glass, in which the essential component is calcium-magnesium double carbonate CaCO3∙MgCO3. The paper presents the research results on glasses obtained by smelting pure amphibolite and amphibolite modified with 10 and 20% dolomite additives. The raw material used was mined in the Poland region of Lower Silesia. The glass melting process was carried out in an electric furnace at 1450 °C for 2 h. The structure and properties of the glasses and crystallization products were determined by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy—Energy Dispersive Spectroscopy (SEM-EDS). Viscosity and Vickers microhardness were also measured. It was found that the modification of amphibolite glass by adding dolomite affects the glasses’ properties and structure. The research results determined the effect of dolomite addition on the properties of alumino-silicate glasses in terms of the mineral fibre products used in the construction industry.

Non-Biological Slaughterhouse Wastewater Treatment with Membrane Processes-An Opportunity for Water Recycling.

The pressure-driven membrane separation processes ultrafiltration (UF) and reverse osmosis (RO) enable the effective purification of wastewater, in particular in combination, allowing organic and inorganic contaminants to be separated from the wastewater. Consequently, this work investigates the suitability of this technology for slaughterhouse wastewater (SWW) recycling. This was investigated by means of laboratory and bench-scale plant membrane experiments, whereby slaughterhouse wastewater (SWW) pre-treated by flotation was first treated with UF and then further purified with RO. Through the process combination UF + RO in the bench scale experiment, a reduction of the parameters total organic carbon (TOC), chemical oxygen demand (COD) of more than 98% and 97% for the parameter total nitrogen (TN) could be achieved. This means that wastewater reuse without product contact can be guaranteed. For direct process water reuse, only the concentration limit for ammonium could not be reached. In addition, scanning electron microscopy (SEM) images and energy dispersive X-ray spectroscopy (EDX) analyses of the RO membrane were carried out before and after the experiment, which did not indicate any scaling effects.

Effect of Al2O3/SiO2 ratio on the chroma and phase compositions of white sulfoaluminate cement clinker

Fe element is the main factor affecting the whiteness of white sulfoaluminate cement (W·SAC). With the reduction of high-quality raw materials, the Fe content of the raw materials used to produce W·SAC has been increasing. In this study, increasing the Al2O3/SiO2 ratio (N) was found to increase the whiteness of W·SAC, which can help to alleviate the scarcity of resources for manufacturing W·SAC. The effect of N on the phase compositions, chroma and hydration of clinker was studied by the Rietveld method, scanning electron microscopy–energy dispersive spectrometry (SEM–EDS), spectrophotometry and calorimetry. The whitening mechanism for W·SAC by increasing N was elucidated. With increasing N, Fe was more dispersed into ye’elimite, and for N above 1.5, 0.5% Fe2O3 completely dissolved into other phases without forming C4AF, which increased the brightness (L*) and greenness (a*) and reduced the yellowness (b*) of the clinker, thereby significantly improving the whiteness. With increasing N, the ye’elimite content increased, the C2S and unquantifiable crystalline phase (ACn) content decreased, and the content of gehlenite (which does not have hydraulic activity) decreased, which increased the overall early hydraulic activity of W·SAC and the accumulated heat of W·SAC hydration.

Experimental study on improving coalbed methane extraction by chemical treatment using acetic acid or ammonium persulfate

AbstractAd‐/desorption and diffusion processes are the key factors controlling methane production from coal. The experiments used samples from methane‐producing coal seams with different contents of carbonate mineral and different ranks. Acid treatment using 1.0 mol/L acetic acid (CH3COOH) and oxidant treatment using 1.0 mol/L ammonium persulfate ((NH4)2S2O8) were conducted on these coal samples to observe the changes in surface functional groups that act as primary sorption sites and pore structure that determines diffusivity by Fourier transform infrared spectrometer, in situ scanning electron microscopy (SEM) imaging and energy dispersive spectroscopy. The results showed that the acidizing‐related mass loss of coal samples is in the range of 3.78%–7.57% due to the complete dissolution of pore‐ and fracture‐filling carbonate minerals. For the coal samples after oxidizing treatment, dissolution evidence can be observed in both carbonate minerals and organic matter, with a mass loss ranging from 2.01% to 3.0%. Acidizing or oxidizing induced dissolution can destroy aliphatic functional groups and the cross‐linked structure of coal, resulting in a decrease in methane adsorption capacity that is beneficial to methane desorption. More opened pores and interconnected fractures can be observed in SEM images due to the dissolution of carbonate minerals, suggesting an alteration of methane diffusion pathways in the coal matrix. Although only some of the carbonate minerals were dissolved following oxidant treatment, coal organic matter is partially oxidized and generates some dissolution pores, which provides more methane diffusion pathways in the coal matrix. Therefore, all the treated coal samples showed a reduction in methane adsorption capacity and an enhancement of desorption capacity and diffusivity. This result suggests that chemical treatment in coal seams using acetic acid or oxidant has the potential to improve coalbed methane extraction.

Effect of a Fast Potential Change on the Early Stage of Zinc Passivation in a Saturated Calcium Hydroxide Solution

The fast and sharp corrosion potential change from the active state to the passive state, that pure zinc plates immersed in calcium hydroxide saturated solutions with and without chlorides spontaneously exhibit at the early stage of passivation, was studied. The corrosion behavior was investigated by corrosion potential monitoring, anodic polarization curves and electrochemical impedance spectroscopy. The zinc surface was characterized by scanning electron microscopy and X-ray energy dispersive spectroscopy. Experimental results show that the presence of chlorides increases the rate of change of potential by 10-fold in the early stage of passivation, producing a porous passivating film of corrosion products mainly made of calcium hydroxy-zincate Ca(Zn(OH)3)2·2 H2O, with a less protective barrier effect than the non-porous film formed without chlorides. On the other hand, a modeling approach was achieved by solving the transient 2D Nernst–Planck equations and considering 12 chemical species. Numerical results confirm that the composition of the chemical products generated on the Zn surface certainly depends on the concentration of Cl¯ ions: Simonkolleite and hidroxides become unstable in the presence of high Cl¯ concentrations, whereas calcium hydroxyl-zincate is the main chemical compound generated on the Zn surface. However, the presence of the latter compound is much more important in electrolytes with very low concentration of Cl¯ ions.

Synthesis and Characterization of Strontium Doped Graphene Oxide Nanocomposite for the Electrochemical Decoloration of a Textile Dye from Aqueous Medium

Strontium-GO composites were synthesized by a facile one-pot approach. Microstructures of the constituent elements of the prepared composite were studied by scanning electron microscopy and X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The characterization of the Sr/GO composites suggested that the disorderly, folded sheet-like accumulation in the graphene matrix. The stoichiometry of elements was estimated and presented in the inset from the area intensity of the peaks in the EDX spectrum. Electrochemical decoloration of an aqueous solution of a textile dye Violet 5BN was investigated under different experimental conditions by using carbon electrodes. Our findings revealed that the electrodes evidenced great dye decoloration abilities to treat solutions containing this dye, in the presence of the synthesized nanocomposite. The influence of the synthesized nanocomposite was remarkable in the electrochemical dye decoloration process and ~100% color removal was found by the addition of 0.004g nano composite per 250 mL of the dye solution.

Fibrous Ferrierite from Northern Italy: Mineralogical Characterization, Surface Properties, and Assessment of Potential Toxicity

Nowadays, fibrous minerals pose as significant health hazards to humans, and exposure to these fibers can lead to the development of severe pulmonary diseases. This work investigated the morphology, crystal structure, chemistry, and surface activity of fibrous ferrierite recently found in northern Italy through an integrated approach using scanning electron microscopy–energy dispersive spectroscopy, electron microprobe, inductively coupled plasma atomic emission spectrometry, X-ray powder diffraction, and electron paramagnetic resonance. Our results show that a notable amount of ferrierite fibers are breathable (average length ~22 µm, average diameter 0.9 µm, diameter-length ratio >> 1:3) and able to reach the alveolar space (average Dae value 2.5 μm). The prevailing extra-framework cations are in the Mg > (Ca ≈ K) relationship, R is from 0.81 to 0.83, and the Si/Al ratio is high (4.2–4.8). The <T-O> bond distances suggest the occurrence of some degree of Si,Al ordering, with Al showing a site-specific occupation preference T1 > T2 > T3 > T4. Ferrierite fibers show high amounts of adsorbed EPR probes, suggesting a high ability to adsorb and interact with related chemicals. According to these results, fibrous ferrierite can be considered a potential health hazard, and a precautionary approach should be applied when this material is handled. Future in vitro and in vivo tests are necessary to provide further experimental confirmation of the outcome of this work.

Artificial weathering of an ordinary chondrite: Recommendations for the curation of Antarctic meteorites

AbstractMeteorites are prone to errestrial weathering not only after their fall on the Earth’s surface but also during storage in museum collections. To study the susceptibility of this material to weathering, weathering experiments were carried out on polished sections of the H5 chondrite Asuka 10177. The experiments consisted of four 100‐days cycles during which temperature and humidity varied on a twelve hours basis. The first alteration cycle consisted of changing the temperature from 15 to 25 °C; the second cycle consisted of modifying both humidity and temperature from 35 to 45% and 15 to 25 °C, respectively; the third cycle consisted of varying the humidity level from 40 to 60%; and the fourth cycle maintained a fixed high humidity of 80%. Weathering products resulting from the experiments were identified and characterized using scanning electron microscopy–energy dispersive spectroscopy and Raman spectroscopy. Such products were not observed at the microscopic scale after the first cycle of alteration. Conversely, products typical of the corrosion of meteoritic FeNi metal were observed during scanning electron microscope surveys after all subsequent cycles. Important increases in the distribution of weathering products on the samples were observed after cycles 2 and 4 but not after cycle 3, suggesting that the combination of temperature and humidity fluctuations or high humidity (>60%) alone is most detrimental to chondritic samples. Chemistry of the weathering products revealed a high degree of FeNi metal corrosion with a limited contribution of troilite corrosion. No clear evidence of mafic silicate alteration was observed after all cycles, suggesting that postretrieval alteration remains limited to FeNi metal and to a lesser extent to troilite.