Variation In Elemental Composition Research Articles

Effect of powder and process parameters on in-situ alloying of nitinol during laser powder bed fusion

Powder characteristics such as flow energy, bulk density, compressibility, morphology, particle size distribution (PSD) and laser energy absorbtivity have a significant impact on the Laser Bed Powder Fusion (L-PBF) process. The impact of powder characteristics on in-situ nickel-titanium alloy formation within the L-PBF process is not well understood. In this work, the characteristics of nickel, titanium and two elemental blends of nickel-titanium powder were compared with those of a pre-alloyed nitinol powder. L-PBF solidification tracks were generated using selected powders and characterised for resulting track dimensions and chemical homogeneity. This study demonstrates that the melt homogenisation time and the size of titanium particles relative to nickel particles are critical factors for successful in-situ alloying of nitinol within the L-PBF process. The variation in elemental composition within solidification track cross sections, as measured by EDX point spectra, was found to increase significantly for laser scanning speeds of 400 mm/s and above. Furthermore, the elemental composition inhomogeneity with increasing laser scan speed was found to be significantly more pronounced for a nickel-titanium powder blend of spherical particles with average titanium particle size of 48 μm compared to an otherwise similar blend with an average titanium particle size of 32 μm. There was no significant difference recorded between solidification track widths of in-situ alloyed blends compared to pre-alloyed blends, indicating that optimal hatch spacing for in-situ alloying is likely to be similar to that required for pre-alloyed powders.

Laboratory investigation on injection of supercritical CO2 into basalt: Implication for CO2 sequestration via mineralization

Hydraulic fracturing can create a fracture network that enables fluid penetration of a basalt formation with otherwise low porosity, offering a site for rapid CO2 mineralization sequestration. Supercritical carbon dioxide (SC-CO2) is a promising fracturing fluid with unique properties, making it well-suited for unconventional oil and gas reservoir stimulation. In this study, experiments of fracturing with water and SC-CO2 were conducted under different injection schemes and formation temperatures. The frackability of basalts was investigated from the perspective of breakdown pressure and fracture morphology. The findings revealed that SC-CO2 fracturing with a low pressurization rate could become an optimized option for enhancing the stimulated effect. The potential of carbon sequestration was roughly estimated based on the area of induced fractures, suggesting that fostering a developed fracture network would aid in the in-situ mineralization and storage of carbon. The variation of element composition obtained from basalt slices containing fractures induced by SC-CO2 under different reaction conditions verified the role of water participation and time scale in the mineralization effect.

Assessment of seasonal variations in particulate matter accumulation and elemental composition in urban tree species

Outdoor air pollution in urban areas, especially particulate matter (PM), is harmful to human health. Urban trees and shrubs provide crucial ecosystem services such as air pollution mitigation by acting as natural filters. However, urban greenery comprises a particular biodiversity, and different plant species vary in their capacity to accumulate PM. Twenty-two plant species were analyzed and selected according to their leaf traits, the different fractions of PM accumulated on the leaves (large - PML, coarse - PMC, and fine - PMF) and their chemical composition. The study was conducted in four city zones: urban traffic (UT), urban background (UB), industrial (IND), and rural (RUR), comparing winter (W) and summer (S) seasons. The average PM levels in the air and accumulated on the leaves were higher in W than in S season. During both seasons, the highest PM accumulated on the leaves was recorded at the UT zone. Nine species were selected as the most suitable for accumulating PML, seven as the most efficient for accumulating PMC, and six for accumulating PMF. The leaf area and leaf roundness were correlated negatively with PM accumulation. The evergreen species L. nobilis was indicated as suitable for dealing with air pollution based on PM10 and PM2.5 values recorded in the air. Regarding the PM element and metal composition, L. nobilis, Photinia x fraseri, Olea europaea, Quercus ilex and Nerium oleander were selected as species with notable elements and metal accumulation. In summary, the study identified species with higher PM accumulation capacity and assessed the seasonal PM accumulation patterns in different city zones, providing insights into the species interactions with PM and their potential for monitoring and coping with air pollution.

Structural and Compositional Changes in Two Marine Shell Traditional Chinese Medicines: A Comparative Analysis Pre- and Post-Calcination.

Arcae concha and Meretricis concha cyclinae concha are two marine shellfish herbs with similar composition and efficacy, which are usually calcined and used clinically. This study investigated variations in the inorganic and organic components of Arcae concha and Meretricis concha cyclinae concha from different production regions, both Arcae concha and Meretricis concha cyclinae concha. The aim was to enhance the understanding of these two types of marine shell traditional Chinese medicine (msTCM) and provide a foundation for their future development and application. Spectroscopic techniques, including infrared spectroscopy, X-ray spectroscopy, and X-ray fluorescence spectroscopy, were used to analyze the calcium carbonate (CaCO3) crystal and trace elements. Thermogravimetric analysis was used to investigate the decomposition process during heating. The proteins were quantified using the BCA protein assay kit. Principal component analysis (PCA) was used to classify inorganic elements in the two marine shellfish traditional Chinese medicines. No significant differences among the various production regions. The crystal structure of CaCO3 in the raw products was aragonite, but it transformed into calcite after calcination. The contents of Ca, Na, Sr, and other inorganic elements were highest. The protein content was significantly reduced after calcination. Therefore, these factors cannot accurately reflect the internal quality of TCM, rendering qualitative identification challenging. CaCO3 dissolution in the decoction of Arcae concha and Meretricis concha cyclinae concha increased after calcination, aligning with the clinical application of calcined shell TCM. PCA revealed the inorganic elements in them, indicating that the variation in trace element composition among different drugs leads to differences in their therapeutic focus, which should be considered during usage. This study clarified the composition and structure changes of corrugated and clam shell before and after calcining, and laid the foundation for the comprehensive utilization of Marine traditional Chinese medicine. These technical representations reveal the differences between raw materials and processed products, which will provide support for the quality control of other shellfish TCMS.

Seeds exhibit the most stable elemental composition with nitrogen addition in an Inner Mongolian grassland

Variation in biomass elemental composition of grassland plants may have important implications for ecosystem functioning in response to global change. However, relevant studies have mostly focused on variation of nitrogen (N) and phosphorus (P) concentrations in plant leaves, while few studies have evaluated other elements and plant organs of grassland species. Here, we examined the effects of N addition on multi-element concentrations, and analyzed their patterns across different organs (leaf, stem, root and seed) of five plant species in a steppe community of the Inner Mongolian grassland. Our results showed that seeds exhibited the most stable elemental composition with N addition, and that manganese (Mn) and iron (Fe) concentrations were substantially more variable than macro-elements in response to N addition. In particular, we identified a set of significant negative relationships between elemental concentrations and their corresponding CVs (coefficients of variation) for all plant organs as a whole and for each individual organ. We further found that changes in soil pH and the availability of soil nutrients contributed mostly to variation in the biomass elemental composition of major plants in this community. These findings are important for accurately assessing the effects of N deposition on the biochemical cycling of nutrient elements in grassland ecosystems, and provide critical clues for developing effective approaches to adaptively managing grassland resources as well as mitigating the impact of global change on the dryland ecosystems in the Mongolia Plateau.

Comparative Analysis of Macro/Microstructures and Constituents of Sorghum and Reed Straw.

Node-containing straws exhibit superior mechanical properties compared to node-free straw plants, particularly in terms of shear resistance and compression resistance. We explore the relationship between the structure and mechanical properties of straw materials, providing deeper insights for the field of biomechanics. In this study, we focused on two node-containing straw plants, namely sorghum and reed. The main characteristics of sorghum and reed stalks were compared using macroscopic observation, stereomicroscopy, scanning electron microscopy, infrared spectroscopy, and EDS analysis. This study revealed numerous similarities and differences in the macro- and microstructures as well as the elemental composition of sorghum and reed stalks. The functional groups in sorghum and reed stalks were largely similar, with the primary elements being C and O. Distinguishing features included a higher tapering and a slightly larger reduction in wall thickness in sorghum stalks compared to reed stalks. The cross-section of sorghum stalks was filled with pith structures, while reed stalks exhibited a hollow structure. The vascular bundles in sorghum typically showed a paired arrangement, whereas those in reeds were arranged in odd numbers. Furthermore, sorghum straws contained more Cl and no Br, while the parenchyma of reed straws contained higher Br. The C and O proportions of sorghum straws and reed straws are 50-53% (50-51%) and 45-46% (48-49%), respectively. These variations in elemental composition are believed to be correlated with the mechanical properties of the materials. By conducting a detailed study of the micro/macrostructures and material composition of sorghum and reed straw, this paper provides valuable insights for the field of biomechanics.

Elemental composition of grass phytoliths: Environmental control and effect on dissolution

Plant phytoliths, which represent the main pool of silica (Si) in the form of hydrous Si oxide, are capable of providing valuable information on different aspect of environmental issues including paleo-environmental reconstruction and agricultural sustainability. Phytoliths may have different chemical composition, which, in turn, affects their preservation in soils ad impacts terrestrial cycle of the occluded elements including micro-nutrients and environmental toxicants. Yet, in contrast to sizable work devoted to phytoliths formation, dissolution and physico-chemical properties, the mechanisms that control total (major and trace) elemental composition and the impact that various elements exert on phytolith reactivity and preservation in soils remains poorly known. In order to fil this gap in knowledge, here we combined two different approaches – analytical trace element geochemistry and experimental physical chemistry. First, we assessed full elemental composition of phytoliths from different plants via measuring major and trace elements in 9 samples of grasses collected in northern Eurasia during different seasons, 18 grasses from Siberian regions, and 4 typical Si-concentrating plants (horsetail, larch, elm and tree fern). We further assessed the dissolution rates of phytoliths exhibiting drastically different concentrations of trace metals.In the European grasses, the variations of phytolith chemical composition among species were highly superior to the variations across vegetative season. Compared to European samples, Siberian grass phytoliths were impoverished in Ca and Sr, exhibited similar concentrations of Li, B, Na, Mg, K, V, Zn, Ni, Mo, As, Ba, and U, and were strongly enriched (x 100–1000) in lithogenic elements (trivalent and tetravalent hydrolysates), P, Mn, Fe and divalent metals. Overall, the variations in elemental composition between different species of the same region were lower compared to variations of the same species from distant regions.The main factors controlling phytoliths elemental composition are the far-range atmospheric (dust) transfer, climatic conditions (humidity), and, in a lesser degree, local lithology and anthropogenic pollution. Despite significant, up to 3 orders of magnitude, difference in TE composition of grass and other plant phytoliths, the dissolution rates of grass phytoliths measured in this study were similar, within the experimental uncertainty, to those of other plants studied in former works. Therefore, elemental composition of phytoliths has relatively minor impact on their preservation in soils.

Synthesis and characterization of b-site controlled la-based high entropy perovskite oxides

High entropy perovskite oxide materials are a highly promising class of materials with a wide range of potential applications. They offer a unique combination of perovskite oxides and high entropy oxides, making them suitable for various fields, particularly in electrochemical energy storage systems and hydrogen production. Given the growing demand for clean energy and efficient energy storage solutions, the development of high entropy materials holds great significance. In this study, a cost-effective and rapid fabrication method was employed to produce several single-phase high entropy perovskite oxides by altering the B-site cations. The results demonstrated that these high entropy perovskite oxides could be synthesized with the same crystal structure, despite having significantly different elemental compositions. These variations in elemental composition led to differences in lattice parameters, metal-oxygen bond strengths, and oxygen vacancy content within the materials. Understanding and manipulating these factors can have important implications for the design of high entropy materials for energy storage and other applications.

Justicia americana exhibits stem density–aboveground biomass relationships and variability in elemental composition and isotopic signature across tissue types and land use gradients

Riverine macrophytes are increasingly understood to influence both the physical and chemical dynamics of rivers by creating biogeochemical hotspots and stabilizing benthic sediments. They contribute carbon and nutrients to both aquatic and adjacent terrestrial ecosystems through senescence and herbivory. Here, we report the relationships between Justicia americana biomass, stem length, and stem density, and % carbon (%C), % nitrogen (%N), C:N, δ15N, and δ13C relationships between tissues types (roots, stems, and leaves). Additionally, we report the effects of land use on the plant's tissue. We found that (1) J. americana stem density and dry biomass were positively correlated ( P < 0.001); (2) δ13C and %N were significantly different in leaf and root tissue; (3) δ13C and δ15N were both positively correlated across tissue types; (4) Leaf C:N was less than ½ of root and stem tissue; (5) %C in leaf tissue was positively correlated ( P < 0.05) with forest cover and negatively correlated with urbanization and watershed area; and (6) provide evidence that J. americana utilizes a C3 photosynthetic pathway. Overall, this study provides novel insight into the ecology of J. americana by elucidating the nutritional quality of different plant tissues and stoichiometric changes in the plant in response to land use.

Continuous vs. discontinuous garnet growth in mylonitic micaschists from northeastern Sardinia, Italy: Evidence from LA-ICPMS trace element mapping

Garnet with complex, discontinuous zoning is a common occurrence in metamorphic terrains, and the relationship between major and trace element zoning can provide insight into the metamorphic evolution of the host rock. Mylonitic micaschists along the Posada-Asinara Shear Zone in the Axial Zone of the Sardinia Variscan chain contain garnet porphyroblasts, enveloped by the S2 schistosity, with distinct core and rim domains. A large garnet porphyroblasts was investigated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) mapping. The major element compositional variation follows a bell-shaped zoning, with Ca and Mn contents progressively decreasing, and Fe and Mg increasing, from the core to the outer rim. LA-ICPMS mapping revealed a thin and sharp annular enrichment zone in Y, Sc, Dy, Ho, Er, Tm at the mantle-rim boundary. The trace element (TE) compositional profiles show a central enrichment area for HREE (Tm, Yb, Lu). This enrichment decreases progressively, as a function of atomic number, for Er, Ho and Dy. Elements with even lower atomic number (Tb, Gd, Eu and Sm), are depleted in this central domain, but their content increases in broad shoulders towards the garnet rim. The position of these lateral shoulders migrates progressively rimwards with decreasing atomic number. The REE distribution, trend and behavior in the growth zones of the garnet is an example of TE control during a continuous growth ruled by diffusion-limited REE uptake. The Y + HREE annular enrichment zone, interpreted as resulting from a decrease in the garnet growth rate, reflects a short-lived episode in the garnet growth history.

Characteristics of high-power impulse magnetron sputtering (HiPIMS) deposited nanocomposite-TiAlSiN coating under variable pulse frequencies

In the present study, nanocomposite-TiAlSiN coatings were deposited on WC-Co blocks using HiPIMS technology by varying pulse frequency. Its immediate effect on V–I signature and subsequent results on coating characteristics was critically investigated. Both substrate and target were negatively biased in pulsed mode but the voltage pulses on substrate was set with an offset of 40 μs, with respect to those on targets to avoid gas ion entrapment within coating. Variation of elemental composition, cross-sectional morphology, surface topography, hardness, and adhesion strength of the coating deposited under different pulsed frequencies, were analyzed in depth. TiAlSiN at the highest frequency, showed significant improvements in hardness and scratch resistance. A significant rise in Lc3 was recorded to be from 137.5 to 158.5 N when the pulse frequency was increased from 1 to 4 kHz. On the other hand, the peak target current was found to decrease from 340 A to 106 A. XRD spectra of TiAlSiN showed a peak shift from AlN (200) to TiAlN (200). Higher deposition rates were achieved with higher frequency but a compromise on surface smoothness, which was measured (Sa) with an increase from 9.42 to 14.32 nm.

Ablation resistance of SiC-modified nanocomposite ceramic coating prepared by LPDS method on titanium alloy

To enhance the ablation resistance of Ti6Al4V alloy, a SiC-modified nanocomposite ceramic coating was fabricated by a novel one-step liquid plasma-assisted particle deposition sintering (LPDS) method. A microarc oxidation (MAO) ceramic coating was prepared on the surface of titanium alloy as a comparison. The micromorphologies and formation mechanisms of two ceramic coatings were investigated with the assistance of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). The thickness of the SiC nanocomposite coating (about 39 μm) was significantly increased by 129% compared to the MAO coating (about 17 μm). Additionally, ablation tests of Ti6Al4V alloy, MAO coating, and SiC nanocomposite coating were conducted at 1000 °C using a butane gas lance. Then, the variation of microstructure, phases, elemental composition, and thickness before and after ablation was also comparatively analyzed. The results indicate that the SiC nanocomposite coating exhibits the smallest thickening (29 μm) after ablation at 1000 °C for 360 s, which is 39% and 46% compared with the Ti6Al4V substrate and MAO coating, respectively. The nanocomposite coating is intact and cracks-free after the ablation test. SiO2, formed during the ablation of SiC nanocomposite coatings, blocks oxygen diffusion into the substrate, which plays a protective role in the coating. Therefore, the SiC nanocomposite coating by a novel LPDS technique exhibits superior ablation resistance to enhance the thermal protection performance of titanium alloy substrate.

Variations in elemental composition of rice (Oryza sativa L.) with different cultivation areas of Ethiopia.

Variations in the elemental composition of rice (Oryza sativa L.) grains, and the link with the growing soil, were investigated across the major production areas of Ethiopia (Fogera, Metema and Pawe). The elements (Ca, Mg, Fe, Zn, Mn, Cu, Ni, Cr, Cd and Pb) were determined by using flame atomic absorption spectroscopy (FAAS), after digesting samples through an optimized procedure with respect to volumes of reagents (HNO3, HClO4 and H2O2), temperature and time. The accuracy of the FAAS method was in the range of 87‒113%. The most abundant element in rice was Mg (414‒561 mg kg-1) followed by Fe (49.4‒168 mg kg-1), while in soil was Fe (11674‒12917 mg kg-1) followed by Mg (619‒709 mg kg-1). Chromium, Cd and Pb were all below the limit of quantitation of the method. The concentrations of the elements, except Zn in rice and Fe in soil, varied significantly (p < 0.05) with the growing region. Notably, rice from Fogera contained more than double Fe, while from Pawe less than half Cu than from the other region. Soils from the rice fields of Pawe, generally, had lower levels of the elements than from the other regions. The order of the abundances of the elements in soil was reflected in the rice grains, except for the reversal between Fe and Mg. However, elemental concentrations were higher in soil than in rice, indicating the absence of bioaccumulation by the rice grains. Furthermore, only copper exhibited a strong positive correlation (r = 0.991) between the rice grain and soil.

Elemental distribution patterns in rock samples from Egypt using neutron activation and complementary X-ray fluorescence analyses

The study utilized instrumental neutron activation analysis (INAA) and X-ray fluorescence (XRF) to accurately analyze the elemental composition of 28 felsite (rhyolite), rock samples. Statistical approaches, including bivariate and multivariate analysis, were employed to characterize the rocks and determine their origin. Major findings include significantly high levels of silicon (297000 ± 4000) mg/kg and low levels were noticed for gold (0.10 ± 0.01) mg/kg. The dominant major elements in the rocks were ranked as follows: silicon > aluminum > potassium > sodium > zirconium > calcium > zinc > manganese. A comparison with the upper continental crust (UCC) revealed higher levels for most elements, except for a few. The study also identified substantial amounts of uranium and thorium. Variations in elemental composition were observed both between different profiles and within felsite (rhyolite) rock samples, indicating heterogeneity and varying origins of the rocks. The findings contribute valuable baseline data for the area and highlight its economic significance for Egypt. Additionally, the study addresses the integration of results from different analytical methods, providing a comprehensive answer to this issue.

Major, trace element and Sr-Nd isotope evidence for a sublithospheric mantle source for the Umkondo large igneous province

The Mesoproterozoic (1.11 Ga) Umkondo large igneous province (LIP) in southern Africa and Antarctica was emplaced in < 5 Myr and is dominated by low-Ti tholeiitic doleritic-gabbroic sills. It is of particular interest because it is the least studied LIP in southern Africa with both sublithospheric and lithospheric mantle sources proposed and it coincides with the early assembly of Rodinia, so it has importance in understanding the nature of magmatism and tectonics in and around the Kalahari craton during the Mesoproterozoic. In this study, we compiled a large database of existing (∼750) and new (∼100) major and trace element data for the Umkondo province, as well as 42 new Sr-Nd isotopic measurements, to provide constraints on its magma sources and geochemical evolution. Major element compositional variations in the low-Ti tholeiites are explained by low-pressure (1 kbar) three-phase fractional crystallisation (olivine, clinopyroxene and plagioclase) of a parent magma with ∼ 10 wt.% MgO in oxidising conditions (QFM + 1). Inverse models show that the low-Ti tholeiitic magmas were derived as residual melts after the crystallization of 12%–33% olivine from primary komatiitic-basaltic magmas (up to ∼ 20 wt.% MgO) in equilibrium with mantle olivine (Fo90). Low Sm/Yb and TiO2/Yb-Nb/Yb indicate that the primary magmas were derived by 2%–20% shallow (40–50 km) partial melting of spinel lherzolite. High Sm/Yb is restricted to dyke swarms and may imply limited magma production from deeper (up to ∼ 70 km) garnet lherzolite-like sources. The low-Ti tholeiites of the Umkondo province are enriched in large ion lithophile elements (Rb-Sr-Cs-K) and depleted in high-field strength elements (Zr-Hf-Nb-Ta), indicating the involvement of crustal material and/or the subcontinental lithospheric mantle. This is supported by covariations in Th/Nb, Nb/Yb, Nb/La and Ce/Sm with generally negative ΔNb. Sr-Nd isotopes lend support to the notion that the Umkondo magmas were derived from depleted and/or enriched sublithospheric mantle sources and subsequently contaminated by enriched lithospheric material during emplacement (initial (at 1.11 Ga) 87Sr/86Sr between 0.704820 and 0.737464 and εNd between −8.9 and +5.3). The Vredefort sills are significant as they display the most depleted Sr-Nd isotopic signatures (average initial 87Sr/86Sr of 0.705342 and average εNd of 0.4) and are the least contaminated magma suite in the Umkondo province. Because of (i) the large volume of low-Ti magmas, (ii) evidence of a primary hot and MgO-rich (komatiitic) magma, and (iii) the short duration of magmatism, we suggest that the Umkondo province was formed by plume-induced melting of the sublithospheric mantle beneath the Kalahari craton in an extensional setting. This contrasts with previous suggestions that the heat source developed in response to the “thermal insulation” of the mantle beneath a thickened Kalahari craton in the absence of a mantle plume. There is further evidence from the elevated Zn/Fe that the sublithospheric mantle was lithologically heterogeneous and consisted of mixed peridotite and pyroxenite domains. There is a general lack of ultramafic cumulates in the low-Ti magma suite that may imply there was deeper ponding and storage of the primary magmas that fractionated large quantities of ultramafic rocks. There is also a paucity of high-Ti rocks in the Umkondo province that may reflect limited direct melting of the lithospheric mantle or that they are simply not as well-preserved in this province compared to the Karoo province. The similar trace element and Sr-Nd isotopic compositions of the Umkondo sills in southern Africa with the Borgmassivet sills in Antarctica support the concept that the Kalahari craton and Grunehogna terrane were adjoined at 1.11 Ga. The timing of the Umkondo province indicates there was localised lithospheric extension and upwelling asthenospheric mantle during a time of dominantly compressional tectonics on Earth at the end of the ‘boring billion’.

Field study on variation characteristics of PCDD/Fs and flue gas particles along MSW incinerator

Wet scrubber systems (WSSs) are commonly used for effective flue gas cleaning by removing acid gases and dust. To determine the influence of a WSS on polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and flue gas particles, a field study was carried out in a full-scale municipal solid waste (MSW) incinerator (850 t/d). Phase-separated samples at four flue gas sampling points and two scrubbing solution sampling points were collected for PCDD/F analysis. Two particle samples at the WSS inlet and outlet were simultaneously obtained for TEM-EDS analysis. The memory effect inside the WSS apparently elevated the PCDD/F I-TEQ concentration from 0.0056 to 0.0088 ng I-TEQ Nm−3 by increasing the mass concentrations of 17 congeners. A PCDD/F flux chart was established to interpret the adsorption/desorption mechanism of PCDD/Fs inside the WSS that showed apparent desorption from scrubbing solution. The potential interaction relationship between PCDD/F and flue gas particles were also observed, that was, the desorbed PCDD/Fs from scrubbing solution might be adsorbed by flue gas particles again and therefore enhanced the concentration of solid-phase PCDD/Fs from 0.0236 to 0.0411 ng Nm−3. Furthermore, TEM-EDS analysis indicated that the WSS could evidently remove some soluble particles and reduce the particle size. And the variation in morphology, elemental composition, and distribution of flue gas particles were observed during the scrubbing process. This study systematically analyzed the memory effect of PCDD/Fs and firstly investigated the specific impact of WSS on flue gas particles, thereby improving the comprehensive understanding of WSS applications.

Laves phase and equiaxed grains formation in directed energy deposited AlCuFeNiTi high entropy alloy

In this study, an equiatomic AlCuFeNiTi high entropy alloy (HEA) was successfully fabricated for the first time using pre-alloyed powder with the directed energy deposition method on a Ti-6Al-4V substrate. The alloy was characterized using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), transmission electron microscopy (TEM), and nanoindentation to provide insight into the relationship between its microstructural and nanoscale mechanical properties. The microstructure has three distinct regions, resulting from variation in the alloy's local elemental and crystallographic composition that influences its mechanical properties. The alloy was found to be multiphase with a mostly ordered Heusler structure (L21) and a small amount of FCC structure with traces of C14 Laves in them. Needle-like and spherical-shaped Cu-rich precipitates were also observed in the dendrites. During the solidification process, evidence of dendritic fragmentation was observed, contributing to the alloy having mostly equiaxed grains rather than the commonly observed columnar grains in previously reported additively manufactured (HEAs). Nanoindentation results showed that the dendrites constitute a hard zone, whereas the inter-dendritic regions typify a continuous soft zone, with the dispersed Laves phase having the highest hardness. The presence of Laves phase inside the grain boundaries and its distribution as small-size grains strengthens the grain boundaries. Results highlight the synthesis of an equiaxed HEA with multiple distinct regions that influence its overall mechanical properties.

Tungsten mineralization in the Caojiaba tungsten deposit, southern China: Constraints from scheelite in-situ trace elements and Sr isotope evidence

The Caojiaba tungsten deposit (19.03 Mt@ 0.37 wt% WO3) is hosted in skarn within clastic and carbonate rocks in the Xiangzhong metallogenic province (XZMP), southern China. The genesis of the Caojiaba tungsten deposit remains to be determined, and the role of trace element enrichment and precipitation in scheelite has received little study to date. The deposit is characterized by early prograde skarn overprinted by retrograde skarn assemblage, and then by quartz–scheelite–sulfide veins. Scheelite (CaWO4) across the mineralization stages can be divided into four generations, i.e., scheelite type–1 (Sch1) in the prograde skarn, early scheelite type–2 (Sch2) and late scheelite type–3 (Sch3) grains in the retrograde skarn, and scheelite type–4 (Sch4) in the quartz–scheelite–sulfide vein. In the cathodoluminescence (CL) images, Sch1, Sch2, and Sch3 have core–to–rim textures displaying CL–dark core and CL–bright rims, whereas Sch4 is homogeneous in the CL response across the grains. Sch1 contains high REE + Y and Ta concentrations, and has negative Eu anomalies relative to the other three types of scheelite grains, consistent with the contribution from magmatic fluids related to the tungsten granites. The increasing fluid–rock interaction intensity, precipitation of REE–rich minerals, and pH change in ore–forming fluids increase positive Eu anomalies and LREE/HREE fractionation of scheelite from Sch2 to Sch4. The in-situ initial 87Sr/86Sr ratios of Sch2 range from 0.71727 to 0.72142, which are within or slightly higher than those of the exposed Late Triassic tungsten granites in the XZMP. The broadly increasing initial 87Sr/86Sr ratios of Sch3 (0.72070 to 0.72764) suggest a source derived from magmatic fluids and contribution of the Neoproterozoic Banxi Group slate. This study highlights that the variations in trace element and Sr isotope compositions of scheelite can be used to reveal the source of ore–forming fluids and metal, and constrain the ore–forming processes.

Minerals profile and nutraceutical factors in landraces and hybrid varieties of rice: A comparison

Growing concerns about food security and human health make the identification of beneficial nutritional traits in crops a priority. The aim of the present study was to compare the elemental and nutritional characteristics of landraces and hybrid rice varieties. Landraces, valuable for their biodiversity, are a source of genes that can improve elite varieties and ensure food security. We were able to demonstrate significant variations in elemental composition, especially for calcium, rubidium and selenium, between the two rice types. Pigmented rice varieties were found to be more functional, as they had higher levels of antioxidants such as phenolic compounds, flavonoids and anthocyanins. Statistical analysis using principal component analysis and agglomerative hierarchical clustering grouped the rice varieties into clusters. The results showed that 99.87% of the variance was within the class, and 0.13% was between classes. Many of the landraces studied had high levels of amylose, selenium and antioxidants. Landraces are thus an important source of nutraceutical factors and of high importance for rice improvement and breeding. The results of this study will certainly inform works into improving the dietary system and enable us to direct conventional plant breeding exercises or apply molecular techniques to develop new varieties to ensure on-going food security.

Intraspecific variation in reproductive traits and embryo elemental composition of the crab Hemigrapsus crenulatus (Milne Edwards, 1837) across fluctuating coastal environments along Chilean coasts

The estuarine crab Hemigrapsus crenulatus has a wide distribution range along the coast of the South Pacific Ocean (from 20 °S to 53 S°). This decapod is abundant in these coastal and estuarine habitats and plays a key ecological role as prey of the snook fish (Eleginops maclovinus) and kelp gull (Larus dominicanus). Its diet consists of detritus, dead fish, and crustaceans, and the macroalgae Ulva sp. In response to contrasting environmental conditions and anthropogenic impacts along the Chilean coast, H. crenulatus may present intraspecific variations in its reproductive traits and changes in the elemental composition of its embryos, directly affecting its biological fitness. Along the Chilean coast, female individuals were collected during late spring 2019 and early summer 2020 (from November 2019 to February 2020) in six areas of Chile (north: Tongoy (30°S); south-central: Lenga (36°S), Tubul (37°S); south austral: Calbuco (41°S), Castro (42°S), Quellón (43°S). The environmental conditions (i.e. sea surface temperature, precipitation and chlorophyll α) present during each sampling event were also recorded. We evaluated the reproductive parameters of females (fecundity, reproductive output (RO)) as well as their body size (carapace width and dry weight), volume, water content, dry weight, elemental composition (carbon, hydrogen, nitrogen: CHN), and finally the energy content of their embryos. Our results indicated that the environmental conditions of the sea water temperature, precipitation (proxy of water salinity) and chlorophyll α (proxy of food availability) have direct effects on the reproductive parameters of females and the characteristics of their embryos. We observed a low fecundity and high RO in Calbuco and Quellón, where precipitation was high (i.e. diluted salinity) and temperatures and productivity was low. For embryo traits, the highest values of volume and water content were observed in female crabs from the estuarine areas (i.e. Tongoy, Lenga, Tubul), values much higher than those found in the internal sea of Chile (i.e. Calbuco, Castro, Quellón). For the elemental composition, we observed high nitrogen levels and a low C:N proportion in embryos from female crabs from Lenga (a nitrogen enriched area). Fluctuating environmental variables among localities proved to modulate intraspecific variations in females and embryos of H. crenulatus, revealing different reproductive strategies, particularly in the quality and energy investment per embryo, which subsequently influenced successful embryogenesis and larval survival.