Mineral Crystals Research Articles

Biomimicry of Limpet Teeth with Colloidal Liquid Crystals of Minerals and Polysaccharides

Biomimicry of Limpet Teeth with Colloidal Liquid Crystals of Minerals and Polysaccharides

Igneous intrusion contact metamorphic system and its reservoir characteristics: A case study of Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin, China

Taking the Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin as an example, this study comprehensively utilizes seismic, mud logging, well logging, physical property analysis and core thin section data to investigate the metamorphic reservoir formed by contact metamorphism after igneous rock intrusion. (1) A geological model of the igneous intrusion contact metamorphic system is proposed, which can be divided into five structural layers vertically: the intrusion, upper metamorphic aureole, lower metamorphic aureole, normal sedimentary layers on the roof and floor. (2) The intrusion is characterized by xenoliths indicating intrusive facies at the top, regular changes in rock texture and mineral crystallization from the center to the edge on a microscopic scale, and low-angle oblique penetrations of the intrusion through sedimentary strata on a macroscopic scale. The metamorphic aureole has characteristics such as sedimentary rocks as the host rock, typical palimpsest textures developed, various low-temperature thermal metamorphic minerals developed, and medium-low grade thermal metamorphic rocks as the lithology. (3) The reservoir in contact metamorphic aureole has two types of reservoir spaces: matrix pores and fractures. The matrix pores are secondary “intergranular pores” distributed around metamorphic minerals after thermal metamorphic transformation in metasandstones. The fractures are mainly structural fractures and intrusive compressive fractures in metamudstones. The reservoirs generally have three spatial distribution characteristics: layered, porphyritic and hydrocarbon impregnation along fracture. (4) The distribution of reservoirs in the metamorphic aureole is mainly controlled by the intensity of thermal baking. Furthermore, the distribution of favorable reservoirs is controlled by the coupling of favorable lithofacies and thermal contact metamorphism, intrusive compression and hydrothermal dissolution. The proposal and application of the geological model of the intrusion contact metamorphic system are expected to promote the discovery of exploration targets of contact metamorphic rock in Nanpu sag, and provide a reference for the study and exploration of deep contact metamorphic rock reservoirs in the Bohai Bay Basin.

Determining Stress Orientation in Rock Valley, Nevada, Using Ambient Seismic Noise

AbstractThe stress field and the mechanical properties of rocks are important to consider for nuclear explosion monitoring due to their effect on seismic wave radiation from earthquakes and explosions. At the Rock Valley Direct Comparison site, the regional orientation of the maximum horizontal compressive stress (SHmax) is well constrained, but it is unknown whether there are local heterogeneities. Here, I show that stress-induced anisotropy in nonlinear elasticity can be used to estimate the orientation of SHmax. Rocks have compliant internal contacts, such as fractures and mineral grain boundaries, that respond to applied strains more strongly than individual mineral crystals. This strain response is asymmetric between compressive and dilatational strains and is affected by anisotropy in the ambient stress field. Traditional seismic velocity measurements are of strain-averaged velocity, which is less sensitive than nonlinear elasticity to the behavior of compliant internal contacts and therefore the stress field and fracture behavior. My results show that the orientation of SHmax measured using ambient seismic noise aligns with regional estimates, with some heterogeneity that can also be explained by the limitations of the seismic array. I demonstrate the potential of a passive technique for monitoring the stress field in places that currently lack local measurements.

Research on the Properties of Steel Slag with Different Preparation Processes.

To promote the resource utilization of steel slag and improve the production process of steel slag in steelmaking plants, this research studied the characteristics of three different processed steel slags from four steelmaking plants. The physical and mechanical characteristics and volume stability of steel slags were analyzed through density, water absorption, and expansion tests. The main mineral phases, morphological characteristics, and thermal stability of the original steel slag and the steel slag after the expansion test are analyzed with X-ray diffractometer (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG) tests. The results show that the composition of steel slag produced by different processes is similar. The main active substances of other processed steel slags are dicalcium silicate (C2S), tricalcium silicate (C3S), CaO, and MgO. After the expansion test, the main chemical products of steel slag are CaCO3, MgCO3, and calcium silicate hydrate (C-S-H). Noticeable mineral crystals appeared on the surface of the steel slag after the expansion test, presenting tetrahedral or cigar-like protrusions. The drum slag had the highest density and water stability. The drum slag had the lowest porosity and the densest microstructure surface, compared with steel slags that other methods produce. The thermal stability of steel slag treated by the hot splashing method was relatively higher than that of steel slag treated by the other two methods.

Nanocrystal residual strains and density layers enhance failure resistance in the cleithrum bone of evolutionary advanced pike fish

Failure-resistant designs are particularly crucial for bones subjected to rapid loading, as is the case for the ambush-hunting northern pike (Esox lucius). These fish have slim and low-density osteocyte-lacking bones. As part of the swallowing mechanism, the cleithrum bone opens and closes the jaw. The cleithrum needs sufficient strength and damage tolerance, to withstand years of repetitive rapid gape-and-suck cycles of feeding. The thin wing-shaped bone comprises anisotropic layers of mineralized collagen fibers that exhibit periodic variations in mineral density on the mm and micrometer length scales. Wavy collagen fibrils interconnect these layers yielding a highly anisotropic structure. Hydrated cleithra exhibit Young's moduli spanning 3-9 GPa where the yield stress of ∼40 MPa increases markedly to exceed ∼180 MPa upon drying. This 5x observation of increased strength corresponds to a change to brittle fracture patterns. It matches the emergence of compressive residual strains of ∼0.15% within the mineral crystals due to forces from shrinking collagen layers. Compressive stresses on the nanoscale, combined with the layered anisotropic microstructure on the mm length scale, jointly confer structural stability in the slender and lightweight bones. By employing a range of X-ray, electron and optical imaging and mechanical characterization techniques, we reveal the structure and properties that make the cleithra impressively damage resistant composites. Statement of significanceBy combining structural and mechanical characterization techniques spanning the mm to the sub-nanometer length scales, this work provides insights into the structural organization and properties of a resilient bone found in pike fish. Our observations show how the anosteocytic bone within the pectoral gridle of these fish, lacking any biological (remodeling) repair mechanisms, is adapted to sustain natural repeated loading cycles of abrupt jaw-gaping and swallowing. We find residual strains within the mineral apatite nanocrystals that contribute to forming a remarkably resilient composite material. Such information gleaned from bony structures that are different from the usual bones of mammals showcases how nature incorporates smart features that induce damage tolerance in bone material, an adaptation acquired through natural evolutionary processes.

Study on the mechanism and stability of microbially induced struvite precipitation (MISP) for enhanced immobilization of uranium

The microbial induced carbonate precipitation (MICP) technique has been shown to immobilize a wide range of heavy metals. However, the MICP process for removing uranium-dominated composite heavy metals ignores the formation of substances such as uranyl carbonate, which can easily lead to uranium migration. Furthermore, the by-product ammonia is one of the bottlenecks limiting the application of MICP. In this work, the microbially induced struvite precipitation (MISP) method was used to enhance U immobilization while reducing by-product contamination. The results showed that the optimal uranium removal rate of the MISP process was increased by 82.98% compared to the MICP. Characterization results confirmed the co-precipitation of U with NH4+ in the form of uramphite and struvite, while the participation of U changed the mineral crystal shape. Stability experiments showed that the maximum release of U from struvite was only 1.27%, which is much lower than the minimum release of U from CaCO3. As a result, the MISP process both enhanced uranium immobilization efficiency, decreased the risk of uranium migration-release, and reduced the environmental impact of the by-product ammonia. These results provided a new perspective for studying U contamination remediation and its co-precipitation behavior in microbial mineralization.

Protracted and Progressive Crustal Melting during Continental Collision in the Pamir and Plateau Growth

Abstract Determining crustal melting in parallel with geodynamic evolution provides critical information on plateau crustal thickening and uplift. Here we investigate the timing and duration of crustal melting through in situ analysis of zircon U–Pb ages, trace elements and Hf–O isotopes, and whole-rock elements and Sr–Nd–Hf isotopes for the granites and high-grade metamorphic rocks from the Pamir Plateau. Zircon dates record protracted crustal melting for both Central Pamir (43–33 and 22–12 Ma) and South Pamir (28–10 Ma). The Pamir Cenozoic granites are characterized by significant elemental and isotopic heterogeneity. The elemental variability within the Pamir Cenozoic granites is dominantly attributed to fractional crystallization of K-feldspar and plagioclase with subordinate biotite from a variably fractionated melt, and the accumulation of early crystallized feldspar during magma ascent. Peritectic mineral entrainment and accessory mineral crystallization had some influence on the geochemical characteristics of the garnet-bearing leucogranite dikes. Zircon Hf isotopes and whole-rock Sr–Nd–Hf isotopes show secular variations for both Central and South Pamir granites. The Central Pamir granites show a mild decrease in whole-rock ƐNd(t) values from Eocene (−4.3 to −4.9) to Miocene (−6.2 to −7.7), and the zircon ƐHf(t) values decrease from c. 40 Ma (+2 to −5) to c. 10 Ma (−4 to −8). In contrast, the South Pamir granites have highly variable whole-rock Sr–Nd–Hf (87Sr/86Sr(i) = 0.7053 to 0.7830; ƐNd(t) = −31.5 to +0.2; ƐHf(t) = −40.0 to +8.2) and zircon Hf isotopes (ƐHf(t) = −31.7 to +7.5) and display a strong decrease in ƐNd(t) and ƐHf(t) values from c. 25 Ma to c. 13 Ma. Geochemical and isotopic data indicate that both the Central and South Pamir experienced crustal melting from juvenile lower crust to ancient lower-middle crustal materials, and Indian crustal materials were incorporated into the melt region of the South Pamir leucogranites from c. 20 Ma. Our study highlights a causal link between a chain of events that includes magma underplating induced by lithosphere thinning and slab breakoff, lithosphere delamination and underthrusting of Indian lithosphere, and formation of the Cenozoic granites in Pamir. This series of processes are incorporated here into a comprehensive model for the geodynamic evolution of the Pamir during the India–Asia collision.

The chromosome resembles more a crystal than other cell organelles

Several organelles in the cell, such as mitochondria and chloroplasts, are limited by one or several membranes, whereas others, like ribosomes and nucleoli have no membranes. Their shape is decided by their inner atomic coherence. The mineral crystal has no delimiting membranes built by separate atoms. Atomic self-assembly determines its pattern. Remarkable is that the chromosome has no outer membrane limiting its pattern as seen in the light and electronic microscopes. Its pattern is also decided by the inner coherence of the atomic configuration of its DNA, RNA, and proteins. The chromosome appears to occupy an intermediate position between a mineral crystal and a cell organelle when its atomic configuration is considered.

High-precision analysis of carbon isotopic composition for individual CO2 inclusions via Raman spectroscopy: Addressing issues arising from the laser-heating effects

The carbon isotopic composition of carbon dioxide fluid inclusions trapped within minerals reflects the origin and evolution of the CO2-bearing fluids and melts. Recently, we developed a highly accurate method using Raman spectroscopy to determine the carbon isotopic composition of CO2 fluid inclusions, by simultaneously collecting 13CO2 and hot bands at a controlled temperature, and using the peak height ratio of 13CO2 and one of hot bands near 1410 cm−1 (HR) to determine δ13C value. This microanalytical technique enables precise measurements of the δ13C values of different CO2 fluid inclusions within zoned mineral crystals to reveal the multiple-stages evolution of CO2-bearing fluids and melts. However, when studying fluid inclusions hosted within high laser heating coefficient minerals such as olivine and pyroxene in mantle xenoliths, local temperature near the inclusions will be higher than the temperature controlled by heating-cooling stage. To address this issue, we examined the effects of laser heating on CO2 isotopic standard samples sealed in the silica capillary, and developed a novel procedure to determine the δ13C values of natural fluid inclusions by using two CO2 standard samples with known carbon isotopic compositions. The proposed workflow successfully determines the δ13C values of natural CO2 inclusions, with an average deviation of 0.58 ‰ between the measurements and the model.

Assessment of the dynamic growth and potassium solubilization capability of three novel bacteria

Abstract. Bangun IH, Ketaren BR, Munar A, Sembiring P, Nurhajijah, Abdi A, Sitorus RS. 2024. Assessment of the dynamic growth and potassium solubilization capability of three novel bacteria. Biodiversitas 25: 177-185. Clay minerals are essential components that play a crucial role in soil cation exchangeable capacity and optimal plant growth. These components, including potassium (K), have the ability to bind with mineral crystals in the soil. Several studies have shown that K-solubilizing bacteria can facilitate the solubility of potassium, leading to optimal availability. However, the use of bacteria as biofertilizers is still limited due to challenges related to survival and growth patterns. To address these challenges, it is important to monitor the growth of the microbes and enhance their selection process to achieve effective utilization. Therefore, this study aimed to determine the bacterial growth dynamics and potential of Burkholderia paludis IHB_01, Burkholderia cepacia IHB_02, and Paraburkholderia phymatum IHB_03 in enhancing soil cation availability on clay minerals. The results showed a common initial adaptation phase among the 3 bacterial strains, followed by distinct exponential growth patterns. Burkholderia cepacia IHB_02 had the longest exponential growth phase, showing efficient resource utilization and extended growth. The results of soil cation enhancement by these bacteria showed that there were no major changes in measured parameters, such as total K, CEC, pH, and organic carbon. Furthermore, the variation in K exchange, organic carbon, and Na exchange provided insights into their unique interactions in the soil. The non-significant impact on potassium-related parameters in this study could be attributed to the presence of antagonistic cation interactions.

Molecular assembly indices of mineral heteropolyanions: some abiotic molecules are as complex as large biomolecules.

Molecular assembly indices, which measure the number of unique sequential steps theoretically required to construct a three-dimensional molecule from its constituent atomic bonds, have been proposed as potential biosignatures. A central hypothesis of assembly theory is that any molecule with an assembly index ≥15 found in significant local concentrations represents an unambiguous sign of life. We show that abiotic molecule-like heteropolyanions, which assemble in aqueous solution as precursors to some mineral crystals, range in molecular assembly indices from 2 for H2CO3 or Si(OH)4 groups to as large as 21 for the most complex known molecule-like subunits in the rare minerals ewingite and ilmajokite. Therefore, values of molecular assembly indices ≥15 do not represent unambiguous biosignatures.

Characterization of the mechanical properties of the mouse Achilles tendon enthesis by microindentation. Effects of unloading and subsequent reloading

The fibrocartilaginous tendon enthesis, i.e. the site where a tendon is attached to bone through a fibrocartilaginous tissue, is considered as a functionally graded interface. However, at local scale, a very limited number of studies have characterized micromechanical properties of this transitional tissue. The first goal of this work was to characterize the micromechanical properties of the mineralized part of the healthy Achilles tendon enthesis (ATE) through microindentation testing and to assess the degree of mineralization and of carbonation of mineral crystals by Raman spectroscopy. Since little is known about enthesis biological plasticity, our second objective was to examine the effects of unloading and reloading, using a mouse hindlimb-unloading model, on both the micromechanical properties and the mineral phase of the ATE. Elastic modulus, hardness, degree of mineralization, and degree of carbonation were assessed after 14 days of hindlimb suspension and again after a subsequent 6 days of reloading. The elastic modulus gradually increased along the mineralized part of the ATE from the tidemark to the subchondral bone, with the same trend being found for hardness. Whereas the degree of carbonation did not differ according to zone of measurement, the degree of mineralization increased by >70 % from tidemark to subchondral bone. Thus, the gradient in micromechanical properties is in part explained by a mineralization gradient. A 14-day unloading period did not appear to affect the gradient of micromechanical properties of the ATE, nor the degree of mineralization or carbonation. However, contrary to a short period of unloading, early return to normal mechanical load reduced the micromechanical properties gradient, regardless of carbonate-to-phosphate ratios, likely due to the more homogeneous degree of mineralization. These findings provide valuable data not only for tissue bioengineering, but also for musculoskeletal clinical studies and microgravity studies focusing on long-term space travel by astronauts.

Remediation of Cd-polluted soil, improving Brassica napus L. growth and soil health with Hardystonite synthesized with zeolite, limestone, and green Zinc oxide nanoparticles

Acidic laterite may exhibit high cadmium (Cd) bioavailability and thus can cause potential environmental and human health hazards. We investigated the soil addition of zeolite (Ze), limestone (LS), and green synthesized zinc oxide nanoparticles (G-ZNPs) as sole soil additives, their mixture (LZ-Zn) and synthesized hardystonite {(S-Hyd), produced by calcination of all three additives}, to reduce Cd uptake and mitigate oxidative stress in Brassica napus L. (B. napus). Synthesis of hardystonite (S-Hyd) was confirmed by SEM, EDS, FTIR, and XRD and showed superior results than other additives for improving various parameters of plants and soil. Porous structure, larger surface area, alkaline properties, different functional groups (-OH, CO32−, Zn–O), and mineral crystals (cristobalite, calcite, zincite, and hardystonite) in S-Hyd facilitated Cd adsorption, reducing DTPA-Cd by 50%, compared to sole Cd polluted soil. S-Hyd enhanced soil enzymes and notably reduced Cd concentrations in plant roots and shoots by 59% and 78%, respectively, thereby decreasing the expression of Cd transport-related genes in plants. Interestingly, S-Hyd enhanced antioxidative defense, bioactive compounds, and photosynthetic pigments while lowering oxidative stress at molecular and physiological levels of plants. Economic comparison revealed that using S-Hyd was 87.0% more cost-effective than naturally occurring hardystonite (Hyd) to remediate Cd-polluted soil.

Synergistic inhibition of green rust crystallization by co-existing arsenic and silica.

Arsenic and silica are known inhibitors of the crystallization of iron minerals from poorly ordered precursor phases. However, little is known about the effects of co-existing As and Si on the crystallization and long-term stability of mixed-valence Fe minerals such as green rust (GR). GR usually forms in anoxic, Fe2+-rich, near-neutral pH environments, where they influence the speciation and mobility of trace elements, nutrients and contaminants. In this work, the Fe2+-induced transformation of As- and/or Si-bearing ferrihydrite (FHY) was monitored at pH 8 ([As]initial = 100 μM, Si/As = 10) over 720 h. Our results showed that in the presence of As(III) + Si or As(V) + Si, GR sulfate (GRSO4) formation from FHY was up to four times slower compared to single species system containing only As(III), As(V) or Si. Co-existing As(III) + Si and As(V) + Si also inhibited GRSO4 transformation to magnetite, contrary to systems with only Si or As(V). Overall, our findings demonstrate the synergistic inhibitory effect of co-existing Si on the crystallization and solid-phase stability of As-bearing GRSO4, establishing an inhibitory effect ladder: As(III) + Si > As(V) + Si > As(III) > Si > As(V). This further highlights the importance of GR in potentially controlling the fate and mobility of As in ferruginous, Si-rich groundwater and sediments such as those in South and Southeast Asia.

Molecular dynamics simulation of the initial stage induction of alkali-activated aluminosilicate minerals.

With the increasing global concern over carbon emissions, geopolymers have garnered significant attention due to their energy-saving, waste utilization, and eco-friendly advantages. Metakaolin and slag, as aluminum-containing mineral materials in geopolymer production, have been widely studied and applied. Previous research has mainly focused on performance design and theoretical development, while the underlying mechanisms at the microscopic level remain unclear. In this study, we employed molecular dynamics simulations to investigate the microscale reaction behavior of geopolymers, exploring the induction process and structural evolution during the initial stages, and revealing the similarities and differences under alkali activation for different materials. Our findings indicate that the alkali activation process can be divided into two stages: mineral crystal deconstruction and oligomer polymerization. The role of NaOH differs between low-calcium and high-calcium systems, where in the low-calcium system, Na+ substitutes Ca2+ due to Ca2+ deficiency, participating in the formation of the network framework. Moreover, the high-calcium system exhibits a faster formation of the gel phase during alkali activation compared to the low-calcium system. This study provides valuable insights into the research and application of geopolymers.

Different responses of Sinorhizobium sp. upon Pb and Zn exposure: Mineralization versus complexation

Lead (Pb) and zinc (Zn) have been discharged into environment and may negatively impact ecological security. Rhizobia has gained attention due to their involvement in the restoration of metal polluted soils. However, little is known about the responses of rhizobia under Pb and Zn stress, especially the roles played by extracellular polymeric substances (EPS) in the resistance of these two metals. Here, Sinorhizobium sp. C10 was isolated from soil around a mining area and was exposed to a series of Pb/Zn treatments. The cell morphology and surface mineral crystals, EPS content and fluorescent substances were determined. In addition, the extracellular polysaccharides and proteins were characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that Zn stress induced the synthesis of EPS by C10 cells. Functional groups of polysaccharides (CO) and proteins (C–O/C–N) were involved in complexation with Zn. In contrast, C10 resisted Pb stress by forming lead phosphate (Pb3(PO4)2) on the cell surface. Galactose (Gal) and tyrosine played key roles in resistance to the Zn toxicity, whereas glucosamine (N-Glc) was converted to glucose in large amounts during extracellular Pb precipitation. Together, this study demonstrated that C10 possessed different strategies to detoxify the two metals, and could provide basis for bioremediation of Pb and Zn polluted sites.

Renal macrophages monitor and remove particles from urine to prevent tubule obstruction

When the filtrate of the glomerulus flows through the renal tubular system, various microscopic sediment particles, including mineral crystals, are generated. Dislodging these particles is critical to ensuring the free flow of filtrate, whereas failure to remove them will result in kidney stone formation and obstruction. However, the underlying mechanism for the clearance is unclear. Here, using high-resolution microscopy, we found that the juxtatubular macrophages in the renal medulla constitutively formed transepithelial protrusions and "sampled" urine contents. They efficiently sequestered and phagocytosed intraluminal sediment particles and occasionally transmigrated to the tubule lumen to escort the excretion of urine particles. Mice with decreased renal macrophage numbers were prone to developing various intratubular sediments, including kidney stones. Mechanistically, the transepithelial behaviors of medulla macrophages required integrin β1-mediated ligation to the tubular epithelium. These findings indicate that medulla macrophages sample urine content and remove intratubular particles to keep the tubular system unobstructed.

Mechanism of carbonate assimilation by intraplate basaltic magma and liquid immiscibility: example of Wangtian’e volcano (Changbaishan volcanic area, NE China)

The balance of CO2 during abundant basaltic magma production is an important factor of volcanic hazards and climate. In particular, this can be explored based on CO2-rich mantle-derived magmas or carbonate assimilation by basaltic melts. To reconstruct the origin of Fe-rich carbonates hosted by Cenozoic basalts from Wangtian’e volcano (northeast China), we studied elemental compositions of melt, crystalline and fluid inclusions in magmatic minerals as well as the oxygen and carbon isotope compositions of the plagioclase and carbonates from basalts. The crystallization of basaltic magmas occurred in shallow chamber (∼4 km) at temperatures of 1,180°C–1,200°C and a pressure of 0.1 ± 0.01 GPa. Stable Fe-rich carbonates occur in the Wangtian’e tholeiite basalts as groundmass minerals, crystalline inclusions in plagioclase and globules in melt inclusions, which suggests that they crystallized from a ferrocarbonate melt. The values of δ18О and δ13С in the minerals analyzed by laser fluorination method are in line with the sedimentary source of Fe-rich carbonates, indicating assimilation and partial decomposition of carbonate phases. The parent ferrocarbonate melt could be produced during interactions between the basaltic magma and the crustal marbles. The phase diagram and thermodynamic calculations show that the ferrocarbonate melt is stable at a temperature of 1,200°C and a pressure of 0.1 GPa. Our thermodynamic calculations show that carbonate melt containing 73 wt% FeCO3, 24 wt% MgCO3 and 3 wt% CaCO3 is in thermodynamic equilibrium with silicate melt in agreement with our natural observations. The proposed mechanism is crustal carbonate sediment assimilation by the intraplate basaltic magma resulting in the melt immiscibility, production of the ferrocarbonate melt and the following Fe-rich carbonate mineral crystallization during magma residence and cooling.

Historical pyrite “mirrors” from the Ecuadorian Cañari culture, digital microscopy observations, mineralogical and elemental analysis

This research relies on microscopy and digital microscopy observations and spectral analysis techniques: Raman spectroscopy, laser-induced breakdown spectroscopy (LIBS) and particle-induced X-ray emission (PIXE), to recover part of the lost identity of two pyrite (FeS2) cones. Conserved in Paris, at the Muséum National d'Histoire Naturelle (MNHN), the first one is registered MIN000-3519 in the collection of the mineralogist René-Just Haüy, the second one, registered 105.504, is a stray object. All information related to its origin would have been lost during the move (1837–1841) of the collections from the former Cabinet du Jardin du Roy to the new earth science gallery of the MNHN. Our historical research (Gendron, 2022) revealed that the first one, described as an “Inca mirror”, was shipped from Peru around 1760 by the botanist Joseph de Jussieu to his brothers Antoine and Bernard. They also confirmed that these two pyrite cones are archaeological objects of the Ecuadorian Cañari culture (500–1500 AD).Raman analyses conducted on the MIN000-3519 specimen confirm that it was developed on a quartz paragenesis. While the faces observation of no.105.504 reveals that the crystal used for its cut was triglyph twinned, a crystal which must have been cubic or dodecahedral pentagonal. The observation of the technical traces in digital microscopy makes it possible to reconstruct a process of similar cut for the two “mirrors” and help to discover red mineral clusters in the bottom of the crystalline gaps. LIBS analyses were also applied to get complementary information on in-depth element distribution, such as Fe and Al, in order to understand the stratigraphy inside the cracks. Finally, PIXE measurements do not confirm that these two pyrites come from the same deposit. But, this analytical technique is hampered by the nature of the element Fe which offers multiple and random bonding possibilities during the crystallization of iron minerals and by the lack of a comparative sample in the Parisian mineralogic collections.

Interactive mode of biochar-based silicon and iron nanoparticles mitigated Cd-toxicity in maize

Cadmium contamination poses severe environmental and health threats, necessitating effective mitigation strategies. Rice husk biochar (BC) and nanoparticle (NP) treatments are emerging strategies with limited research on their synergistic benefits. This study assesses BC, silicon NPs (nSi), and iron NPs (nFe) modifications (B-nSi, B-nFe, and B-nSi-nFe) to reduce Cd-bioavailability in soil and its toxicity in maize, not reported before. Characterization of amendments validated, nSi and nFe attachment to BC, forming new mineral crystals to adsorb Cd. We found that B-nSi-nFe induced Cd-immobilization in soil by the formation of Cd-ligand complexes with the effective retention of NPs within microporous structure of BC. B-nSi-nFe increased soil pH by 0.76 units while reducing bioavailable Cd by 49 %, than Ck-Cd. Resultantly, B-nSi-nFe reduced Cd concentrations in roots and shoots by 51 % and 75 %, respectively. Moreover, the application of B-nSi-nFe significantly enhanced plant biomass, antioxidant activities, and upregulated the expression of antioxidant genes [ZmAPX (3.28 FC), ZmCAT (3.20 FC), ZmPOD (2.58 FC), ZmSOD (3.08 FC), ZmGSH (3.17 FC), and ZmMDHAR (3.80 FC)] while downregulating Cd transporter genes [ZmNramp5 (3.65 FC), ZmHMA2 (2.92 FC), and ZmHMA3 (3.40 FC)] compared to Ck-Cd. Additionally, confocal microscopy confirmed the efficacy of B-nSi-nFe in maintaining cell integrity due to reduced oxidative stress. SEM and TEM observations revealed alleviation of Cd toxicity to stomata, guard cells, and ultracellular structures with B-nSi-nFe treatment. Overall, this study demonstrated the potential of B-nSi-nFe for reducing Cd mobility in soil-plant system, mitigating Cd-toxicity in plants and improving enzymatic activities in soil.