Distribution Of Elements Research Articles

Original Research Paper

Plants inhabiting adverse growth conditions compete against stresses by the endogenous regulatory elements viz., promoters and terminators at the ‘right time’ (time-of-stress-act), ‘right place’ (tissue-of-act), and ‘right expression’ (time-of-transcription). Heat stress at the reproductive stage impedes pollen viability and stigma receptiveness, affecting the seed set. Prosopis cineraria, the dominant desert-inhabiting legume tree, is heat- and drought-tolerant. The distribution of heat shock elements in a heat-inducible promoter determines the magnitudes of target gene expression in different tissues/organs. Relative expression of P. cineraria heat shock protein 18.2 (PcHsp18.2) in alternate months of 2021 displayed the highest expression in summer. The flowers collected in June, the hottest month (47oC) of 2021, exhibited a high expression of PcHsp18.2. The germination of the pollen collected was 80%, and the trees eventually set seeds. Comprehensive analysis of the promoter (pPcHSP18.2) and terminator (tPchsp18.2) of PcHsp18.2 by expressing the gusA in tobacco exhibited the highest expression under heat stress as similar to the expression of PcHsp18.2 in environmental samples. Ectopic expression of gusA under PcHsp18.2 promoter and terminator resulted in an increased seed set due to the viability of pollen and stigma under heat stress. The gusA expression under PcHsp18.2 promoter and terminator was high-fold in anther compared to the Lat52 and g10 (endogenous genes under its promoter and terminator) genes under heat stress. The expression of genes under strong and balanced endogenous inducible promoter and terminator combinations, as in the desert-growing P. cineraria in transgenic plants, enables the development of resilient crops.

Experimental constraints on the role of temperature and pyrogenic mineral assemblage in wildfire-induced major and trace element mobilisation

Wildfires impact a large and increasing proportion of the Earth’s surface. With documented soil surface temperatures of up to ∼850 °C, wildfires may fundamentally alter the mineralogy and geochemistry of soils and regolith, more conventionally thought to be dominated by low temperature weathering processes. Here we use an experimental approach to test the effect of temperature on the formation of pyrogenic minerals, and on the distribution and mobility of major, trace and rare earth elements following post-fire chemical weathering. We focus on ferruginous nodules, common Fe-oxide cemented components of soils, which transform from non-magnetic to maghemite-bearing, magnetic nodules under wildfire conditions. These transformations provide a valuable record of fire impacts and facilitate the study of thermal processes and element mobility. Our results show heating produces a typical pyrogenic mineral assemblage of hematite, maghemite, metakaolin and transition alumina. At 900 °C the high temperature Fe2O3 polymorph luogufengite forms, which has never been reported in natural fire-affected substrates and therefore places an upper boundary on palaeowildfire temperatures at the soil-fire interface. Chemical leaching, employed to simulate the impacts of post-fire weathering, demonstrates that formation and subsequent breakdown of these pyrogenic minerals results in increased mobility of several elements including Li, Si, Sc, Cr, Co, Cu, Zn, Rb, Cs, La, Pb and U. Further, we propose that incongruent dissolution of pyrogenic metakaolin may be responsible for the formation of fusic material, an aluminous cement commonly found in soils. We conclude by discussing the significance of these results for the release of potentially toxic metals following a fire, identify trace elements that have the greatest potential to be used as palaeowildfire geochemical proxies (decreased alkali metal concentrations, decreased U/Th ratios, and decreased La compared to other rare earth elements), and the potential impact of wildfire on global geochemical cycles.

Synchrotron-aided exploration of REE recovery from coal fly ashes within a Canadian context

Coal ashes in Canada have gained attention as a potential source for recovering rare earth elements (REE) from industrial waste. However, the complex chemical properties of coal ashes have made it difficult to determine the desirability, feasibility, and viability of REE recovery. To address this issue, this study systematically investigated distribution and structural information, speciation and chemical-binding state, and purity and extraction capacity of REE in multiple Canadian coal ashes (i.e., 2 fly ash and 1 bottom ash samples) through synchrotron-based X-ray fluorescence mapping and adsorption spectrum analyses, as well as high-resolution REE sequential extraction quantitation. The results showed that Y, Ce, and La were present in the glass phase of the bottom ash, and the distributions of these REE elements correlated with Ca. The XANES analysis revealed that the dominant form of REE in coal fly ash (CFA) was REE oxides, indicating a transformation during combustion, while Y2O3 and Y2(CO3)3 were the predominant Y species identified in CFA. The study found that there is no correlation between P and REEs, suggesting that REEs in CFA may exist as discrete particles rather than being associated with amorphous glass. The extractability of REEs in bottom ash samples was lower than that in fly ash samples. Additionally, the benefits of REE recovery were estimated to be USD 99.82 to 215.21 per ton of fly ash through life cycle analysis, indicating that REE recovery from fly ashes is a promising path to supplement the REE supply chain in Canada.

Quantitative characterization on multistage formation of sedimentary pyrite driven by H2S derived from biogenic process in the northeastern Ordos Basin, China

Negative δ34S values of sedimentary pyrite associated with organic matter are routinely assumed to be the result of biogenic process. However, the distribution and evolution of isotopic values mediated by bacteria across sedimentary strata remains poorly understood. Abundant pyrite-rich nodules (PyRNs) are distributed in the bottom of the sandstone unconformably overlying the coal in middle Jurassic strata in the northeastern Ordos Basin, providing a good opportunity to quantitatively characterize the distribution, morphology and compositions of sulfur isotope and trace element of pyrite in the sandstone influenced by organic matter in the coal. A total of 1007 PyRNs occurs within a range of 4 m from the coal. From bottom to top in the sandstone, the shape of the nodule changes from oval to round on the vertical section, and the length and number gradually decrease at the rate of ~45 mm and ~ 228 for every 1 m increasing in distance, respectively. Microscopically, pyrite occurs as euhedral crystals, and trace element mapping reveals multistage growth (up to a dozen times) and a marked compositional zoning with respect to Co, Ni, As, Se and Mo. The positive correlation between Co and Ni, with ratios of Co/Ni ranging from 0.06 to 0.45, indicates that Fe and those trace elements are sourced from diagenetic fluid. The organic sulfur in coal, serving as a sulfur source, is reduced by bacteria to generate H232S at slow reduction rate. The H232S migrates upwards and reacts with Fe to form pyrite in the sandstone, resulted in extremely low δ34S values (from −53.9 to −43.1 ‰), which gradual decrease both from core to margin in individual grain and at the rate of 2.2 to 8.8 ‰ for every 1 m increasing in distance away from the coal. This study highlights the significant variability of mineralogical (e.g., number, size, morphology) and geochemical (trace elements, sulfur isotope) characteristics of sedimentary pyrite. Results allow the relation of multistage growth of pyrite to biogenic fractionation, and provide fresh insights into biogenically derived sulfur from coals to be fixed in sandstones, which can be applied to quantitative characterization of formation processes of sedimentary minerals controlled by organic matter in sedimentary environments worldwide.

Variations of the elemental composition distribution over the thickness of YBa2Cu3O7-δ thin films obtained by pulsed laser deposition from one target

Epitaxial YBa2Cu3O7‒δ (YBCO) films 150-200 and 300 nm thick, respectively, were deposited on SrTiO3 (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R=0) in the range of 77.4 - 87 R(T) depending on the conditions of deposition from one target with YBa2Cu3O6.8 composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. % ). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena.

Geochemical characterization and reserve estimation of the economic heavy minerals of Sonadia Island, Bangladesh

The goal of the current study is to understand the elemental concentration, reserve assessment, mineralogical composition, and distribution of heavy minerals in the dune sands, foreshore, and backshore of Sonadia Island, Southeast Bangladesh. The study area yielded a number of drill hole composite sand samples that were used for density and magnetic separation of heavy minerals. These samples were then subjected to petrographic characterization, grain counting, mineralogical analyses using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDX), x-ray diffraction (XRD), and bulk sand geochemistry using X-ray fluorescence (XRF). The results of heavy liquid separation show that the total heavy mineral (THM) enrichments in foreshore sand (about 4.86%), backshore sand (about 9.03%), and dune sand (about 22.28%) are significantly higher. After characterizing the sand samples from Sonadia Island based on the abundance of each mineral species, the average content values relative to total economic heavy minerals (TEHM) were determined to be 38.14% ilmenite, 5.74% magnetite, 51.52% garnet, 1.01% zircon, 3.57% rutile, and 0.01% monazite. An SEM–EDX examination reveals that the elemental concentration of ZrO2 in zircon is 66.60%, while the average TiO2 content in rutile is ~ 95%, whereas TiO2 is 45% and the total Fe2O3 is 45.70% in ilmenite. Major phases including amphibole (tremolite) 45.9%, muscovite 15.6%, quartz 12.6%, garnet (almandine) 10.9%, dolomite 7.9%, ilmenite 4.1%, and kaolinite 1.3% are also identified by the XRD pattern. There are an estimated 19,794 tons of garnet in the foreshore sand, 47,324 tons in the backshore sand, and 276,868 tons in the dune sand within the reserve, making it the most prevalent heavy mineral. Ilmenite is the second most common heavy mineral, with quantities detected in the foreshore (15,016 tons), backshore (30,487 tons), and dune sand (215,092 tons).

Confined Element Distribution with Structure-Driven Energy Coupling for Enhanced Prussian Blue Analogue Cathode.

The structural failure of Na2Mn[Fe(CN)6] could not be alleviated with traditional modification strategies through the adjustable composition property of Prussian blue analogues (PBAs), considering that the accumulation and release of stress derived from the MnN6 octahedrons are unilaterally restrained. Herein, a novel application of adjustable composition property, through constructing a coordination competition relationship between chelators and [Fe(CN)6]4- to directionally tune the enrichment of elements, is proposed to restrain structural degradation and induce unconventional energy coupling phenomenon. The non-uniform distribution of elements at the M1 site of PBAs (NFM-PB) is manipulated by the sequentially precipitated Ni, Fe, and Mn according to the Irving-William order. Electrochemically active Fe is operated to accompany Mn, and zero-strain Ni is modulated to enrich at the surface, synergistically mitigating with the enrichment and release of stress and then significantly improving the structural stability. Furthermore, unconventional energy coupling effect, a fusion of the electrochemical behavior between FeLS and MnHS, is triggered by the confined element distribution, leading to the enhanced electrochemical stability and anti-polarization ability. Consequently, the NFM-PB demonstrates superior rate performance and cycling stability. These findings further exploit potentialities of the adjustable composition property and provide new insights into the component design engineering for advanced PBAs.

Effect of processing parameters and carbon to metal ratio on microstructure and mechanical properties of (MoTaTiVW)Cx high entropy carbide produced by reactive spark plasma sintering

(MoTaTiVW)Cx high entropy ceramics with varying carbon to metal ratio in the range of 0.75-0.97 were synthesized by by reactive spark plasma sintering. The effect of ball milling time on particle size, phase evolution and carbon pick-up due to toluene decomposition were studied. Formation of single-phase high entropy carbide having face-centered cubic (FCC) crystal structure was confirmed by X-ray diffraction (XRD), electron backscattered diffraction (EBSD) and Selected area diffraction pattern (SAED) analysis of the sintered compacts. Transmission Kikuchi Diffraction images revealed presence of equiaxed nature of the grains. Transmission electron microscopy images revealed the presence of an intergranular phase at grain boundaries and triple junctions. 3D-Atom Probe Tomography studies showed uniform distribution of elements within the grains with some segregation of impurity elements Fe and Co to the grain boundaries indicating minor contribution of liquid phase sintering to densification. The grain size of single-phase sintered compacts ranged between 1.69 ± 0.60 μm to 4.6 ± 1.0 μm. A low sintering temperature and higher milling time resulted in finer grain size The microhardness was found to increase with milling time and C/M ratio. The microhardness, Young’s modulus and indentation fracture toughness lied between 2221 HV0.1 to 2732 HV0.1, 370 GPa to 473 GPa, 3.6 MPa.m1/2 to 4.4 MPa.m1/2, respectively. The highest microhardness and indentation fracture toughness was found to be 2732 ± 80 HV0.1 and 4.4 MPa.m1/2 on par with reported literature for other high entropy carbides.

Semi-quantitative μLIBS mapping of germanium diffusion between metal and silicate during planetary core–mantle segregation

Understanding the distribution of elements between the cores and mantles of planetary bodies is essential for elucidating the geological and geochemical processes operating during their formation. Because the semi-metallic element Ge shows complex siderophile, chalcophile, and lithophile properties, it is particularly significant for investigating core–mantle segregation and ore deposit formation. Recent advancements in in situ microanalysis techniques, such as μLIBS, have enabled high-resolution elemental mapping of Ge and other trace elements.This study explores the application of μLIBS imaging to investigate the high-temperature/high-pressure distribution of Ge between metallic and silicate matrices analogous to planetary cores and mantles. By cross-calibrating the μLIBS intensities with electron microprobe profile analyses carried out on piston cylinder experimental samples, we produced semi-quantitative Ge maps from which we extracted Ge concentration profiles to assess Ge diffusion from the silicate to the metal. We determined, for the first time, the diffusion coefficient of Ge between metal and silicate to be D(Ge)metal = 4.03E−13 ± 3.6E−14 m2/s at 1 GPa and 1350 °C. Our results demonstrate the capability and efficiency of μLIBS for providing detailed, high-resolution (15 μm) trace element concentration data at few ppm levels, offering a time- and cost-effective alternative to conventional techniques.These findings bring insights on planetesimal differentiation and on chemical exchanges between metal and silicate phases in a magma ocean and between two different metal phases occurring at the bottom of the magma ocean during planetesimal formation.

Rate theory coupling multi-phase-field simulation for neutron irradiation nanophase and vacancy evolution

Radiation damage is a critical problem for the alloys serving under irradiation circumstances where the numerous defects is induced by the cascade collision of radiation particles, the microstructure and mechanical properties will be damaged by the irradiation. By combination of rate theory (RT) and multi-phase-field (MPF) model, the influences of neutron irradiation dose rate (DR) and irradiation temperature are studied on the radiation-enhanced precipitation, vacancies and interstitial atoms in Fe-35Cr-10Al (at.%) alloys. The RT coupled with phase-field simulations capture the radiation induced nanoscale precipitates, clustering of vacancies and interstitial atoms. With the increase of DR, the diffusion of solute atoms is accelerated for the generation of vacancies and interstitial atoms, and the growth and coarsening rate of α′ phase is quickened. The DR affects the distribution of elements between α/α′ phases, high DR promotes the Fe and Al to partition into α phase, Cr into α′ phase in the formation of α′ phase. Therefore, in the steady-state coarsening stage, the high DR leads to the α′ phase to reach the equilibrium composition earlier. As the increase of neutron irradiation temperature, the separation and coarsening rate of α′ phase are accelerated. The simulation morphology and quantitative characteristics are consistent with the experimental results. The coupling of RT and MPF simulation in alloys with point defects and nanophase under neutron irradiation put forward the study tactics and theory understanding for radiation-enhanced multiple microstructure evolutions.

Experimental analysis of free-standing and substrate-constrained Ga-doped ZnO nanostructured thermoelectric films

Developing thermoelectric films without substrates—free-standing films—eliminates substrate-induced effects on performance and meets the flexibility requirements of emerging wearable thermoelectric applications. This study investigates Gallium-doped Zinc Oxide (GZO), composed of abundant and non-toxic elements, to fabricate a substrate-free GZO film via 3D printing and compares its structural, chemical, and thermoelectric properties with those of a substrate-constrained GZO film produced through chemical deposition. Both films exhibited uniform crystal structures and phase purity; however, the substrate-constrained film displayed additional diffraction peaks, suggesting potential substrate interactions. The 3D-printed free-standing film effectively eliminated the tensile stresses observed in the substrate-constrained film. FE-STEM analysis revealed nanostructures with homogeneous elemental distribution in both films, though the substrate-constrained film showed discontinuities, such as pores, likely caused by post-deposition annealing treatment. XPS analysis highlighted differences in chemical states and elemental compositions between the films, influenced by fabrication methods, substrate-induced stresses, and surface energy mismatches. The free-standing GZO film developed through 3D printing exhibited a more balanced incorporation of Zn and O, as it was not subject to substrate or post-deposition annealing constraints. Consequently, it demonstrated a 14 % increase in electrical conductivity and a 91 % improvement in the Seebeck coefficient compared to the substrate-constrained film, resulting in a higher room-temperature power factor of 261 nW/m·K2. These findings underscore the potential of 3D-printed free-standing GZO films to advance thermoelectric applications, offering a promising alternative to overcome the challenges of substrate-constrained films and further drive innovation in the field.

Blowin' in the Wind: Mapping the Dispersion of Metal(loid)s From Atacama Mining.

The Atacama Desert's naturally elevated metal(loid)s pose a unique challenge for assessing the environmental impact of mining, particularly for indigenous communities residing in these areas. This study investigates how copper mining influences the dispersion of these elements in the wind-transportable fraction (<75μm) of surface sediments across an 80km radius. We employed a multi-pronged approach, utilizing spatial modeling to map element distributions, exponential decay analysis to quantify concentration decline with distance, regime shift modeling to identify dispersion pattern variations, and pollution assessment to evaluate impact. Our results reveal significant mining-driven increases in surface concentrations of copper (Cu), molybdenum (Mo), and arsenic (As). Notably, within the first 20km, concentrations peaked at 1,016mgkg⁻1 for Cu, 31mgkg⁻1 for Mo, and a remarkable 165mgkg⁻1 for As. Cu and Mo displayed significant dispersion, extending up to 50km from the source. However, As exhibited the most extensive reach, traveling up to 70km downwind, highlighting the far-reaching ecological footprint of mining operations. Mineralogical analyses corroborated these findings, identifying mining-related minerals in surface sediments far beyond the immediate mining area. Although pollution indices based on the proposed Local Geochemical Background reveal significant contamination across the study area, establishing accurate pre-industrial baseline values is essential for a more reliable assessment. This study challenges the concept of "natural pollution" by demonstrating that human activities exacerbate baseline metal(loid)s levels. Expanding monitoring protocols is imperative to comprehensively assess the combined effects of multiple emission sources, including mining and natural processes, in safeguarding environmental and human health for future generations.

Effect of carbon vacancy on phase formation and mechanical properties of high-entropy (Ti,Nb,Ta,Hf,W)Cx

High-entropy (Ti0.2Nb0.2Ta0.2Hf0.2W0.2)Cx with different carbon vacancies were prepared from raw binary carbides in this study. The influences of stoichiometry, particle size of raw powder, and sintering temperature on phase formation, microstructure, and mechanical properties of (Ti0.2Nb0.2Ta0.2Hf0.2W0.2)Cx were systematically investigated. The results indicate that the introduction of carbon vacancies and using finer raw binary carbide powders can both significantly enhance the formation ability of single-phase composition with uniform elemental distributions. The formation of a high-entropy phase could enhance the Vicker’s hardness. The flexural strength is greatly influenced by the content of carbon vacancy, which is greatly detrimental to flexural strength. The fracture toughness is determined by both the content of carbon vacancies and the presence of secondary phases. By optimizing the content of carbon vacancies, particle size of raw powders, and sintering temperature, (Ti0.2Nb0.2Ta0.2Hf0.2W0.2)C shows super high flexural strength of 743 MPa and fracture toughness of 8.6 MPa m-1/2.

Low-temperature Microwave Sintering of Foam SiC for Mechanical Properties and Electromagnetic Absorption

In this work, the foam SiC ceramics were prepared by conventional and microwave sintering methods at 800 °C combined with organic template impregnation method. The microstructure, crystal structure, and mechanical properties of the samples were evaluated. Compared with conventional sintering, microwave sintering has obvious advantages such as more uniform element distribution, shorter sintering time, and better mechanical properties. Its bending strength and impact resistance reach 2.28 MPa and 4.9 kJ/m2, respectively. The dielectric constant and reflection loss of the samples were tested, and the samples sintered by microwave between room temperature and 500 °C showed better dielectric properties; as well as better microwave absorption performance at frequencies of 2-18GHz. The mechanism of microwave sintering has been elucidated, and the heating method of microwave from inside to outside is an important reason for the excellent mechanical and absorbing properties of materials.

On the effect of energy input on microstructure evolution and mechanical properties of laser beam powder bed fusion processed Ti-27Nb-6Ta biomedical alloy

Additive manufacturing of pre-alloyed Ti-27Nb-6Ta powder by laser beam powder bed fusion (PBF-LB/M) employing a wide range of processing parameters is reported. An in-depth microstructure analysis along the whole process chain from powder feedstock material to additively manufactured bulk structures was conducted employing scanning electron microscopy (SEM) as well as X-ray and high-energy synchrotron diffraction. It is shown that near-fully dense parts (≥ 99.96%) with β+α’’ dual-phase microstructure and very homogenous element distribution are obtained in a large process window. In particular, a considerable influence of the energy input during PBF-LB/M on the solidification microstructure, i.e. phase composition and texture, is found. With increasing energy per unit area (EA) values both an increase in the volume fraction of the bcc β-phase and more pronounced texture components are seen. Furthermore, the mechanical behavior was evaluated under monotonic tensile loading. The PBF-LB/M processed Ti-27Nb-6Ta structures feature good mechanical properties with ultimate tensile strength (UTS) and strain to failure values of up to 768 MPa and 33.8 %, respectively. Due to the strong impact of the energy input during additive manufacturing on the microstructure evolution, however, a significant inverse strength-ductility behavior is observed. While UTS clearly decreases with increasing EA values, strain to failure increases at the same time. The underlying relationships between processing (energy input), microstructure and mechanical properties are explored and rationalized.

Preparation of (Zr0.25Hf0.25Ta0.25Nb0.25)C high-entropy ceramic nanopowders via liquid-phase precursor route at a low temperature of 1500 °C

Using citric acid, ethylene glycol, ZrOCl2·8H2O, HfOCl2·8H2O, NbCl5, and TaCl5 as raw materials, based on the principle of Pechini coordination polymerization, the (Zr0.25Hf0.25Ta0.25Nb0.25)C high-entropy ceramic precursor solution was successfully prepared, and the corresponding high-entropy ceramic powder was formed by pyrolysis at a low temperature of 1500 °C. The molecular structure of the precursor and its pyrolysis products were analyzed and characterized by different analytical and testing methods. The results show that in the precursor solution, the organic compound and the metal ions form a stable three-dimensional macromolecular structure, so that the metal ions show a uniform distribution at the molecular level, shortening the diffusion path during the carbothermal reduction reaction, thereby enabling the formation of the single-phase high-entropy carbide ceramic powders at a relatively low temperature. The obtained ceramic powders have high purity, uniform element distribution, with an average particle diameter of approximately 42 nm and an oxygen content of about 1.61 wt%. The precursor solution prepared in this study has a moderate viscosity of 20–50 mPa s and a high ceramic yield of 45 %, which is ideal for the preparation of high-entropy ceramic matrix composites.

Structure formation mechanism of pectin-soy protein isolate gels: Unraveling the role of peach pectin fractions.

This study investigated the macro & micro properties of the composite gels formed by soy protein isolate (SPI) and peach pectin fractions: water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium carbonate soluble pectin (NSP). Specially, the interaction between pectin fractions and SPI was studied to explain the formation mechanism of the composite gels. WSP, as a high methoxyl pectin, exhibited rich branching (sugar ratio B=3.10). CSP, as a low methoxyl pectin, depicted a high linearity. NSP, with low linearity (sugar ratio A=6.14), contained numerous side chains. Due to the strong interaction between pectin fractions and SPI, the new composites with excellent dense network microstructures were formed, accompanied by increased apparent viscosity, higher G' and G'', and reduced particle size. XRD and FT-IR analysis highlighted the modifications in gel structures. SEM-dispersive X-ray spectroscopy observed elemental distribution and framework composition in pectin-SPI gels. Hydrophobic interaction was the most important chemical force in pectin-SPI binding. Molecular docking results indicated that galacturonic acid in pectin bound more strongly to 7S than to 11S, with tighter hydrogen bonds. Notably, WSP-SPI showed the lowest turbidity, indicating enhanced solubility and particle dispersion, which helped prevent aggregation. CSP-SPI demonstrated the highest G' and G'', ascribing to the high linearity and abundant carboxyl groups in CSP. NSP-SPI showed the highest apparent viscosity and irregular structure. Overall, the texture properties of pectin-SPI gels were driven by pectin's structure properties, which would provide new and valuable information for texture control in gel formulation.

Spatial Distribution of Critical Metals and Chemostratigraphy in Co‐Rich Ferromanganese Nodules in the Northwestern Pacific Ocean

AbstractFerromanganese nodules are important marine storehouses for critical metals and windows for changing oceans. Although advanced in situ analytical techniques have been applied to visualize the elemental distribution in the nodule cross‐sections, their spatial distribution remains largely uncertain. This study addresses this gap by employing micro X‐ray fluorescence mapping of parallel nodule cross‐sections to delineate the spatial distributions of critical metals (Mn, Fe, Co, Ti, Ni, and Cu) in three Co‐rich ferromanganese nodules from the northwestern Pacific Ocean. The 10‐layer Os isotopic compositions of one nodule closely align with the well‐documented marine Os isotope evolution of seawater, providing a chronological framework and a maximum age of ∼36 Ma for these nodules. Three concentric chemostratigraphic layers, labeled L1, L2, and L3, were identified from the inside out, based on microscopic structures and the distributions of critical metals. The early growth stage was marked by Mn‐rich, Si‐rich, and high Mn/Fe ratios, suggesting a diagenetic‐driven process attributed to high paleoproductivity conditions because of the low latitude of the study area at that time. The subsequent growth stages are all hydrogenetic in origin to be rich in Fe, Co, and Ti with low Mn/Fe ratios. The apparent detritus present during the second growth stage of the nodules may correspond to the stronger bottom currents in the early Miocene. The final mineralization stage indicates a more stable environment with diminished bottom current activity, leading to the formation of a dense, laminar hydrogenetic layer.

Probing microstructural evolution behaviors in laser welding of dissimilar GH4169/GH3039 subjected to varied preheating temperatures

The present study examined the evolution of interfacial microstructure and on the element distribution of GH4169/GH3039 dissimilar joints by laser welding under different preheating temperatures. The results indicated that the microstructure observed in the interface layer on the GH4169 side exhibited distinct layers, namely diffusion layer and transition layer, which varied depending on the varied preheating temperature. Within the weld seam (WS), two types of dendrites were predominantly present: lath-like columnar dendrite and cellular dendrite. In the GH3039 side, the grain structure was mainly dominated by columnar dendrites, exhibits perpendicular growth to the fusion line and demonstrates a certain epitaxial growth morphology. Moreover, excessive preheating temperature intensified the migration of elements and phase transition behavior. As the preheating temperature increased, the low-angle grain boundaries (LAGBs) percentage decreased from 13% to 9.4%. The average grain size of the WS at room temperature, 200°C and 400°C is 44.1 μm, 53.3 μm and 58.2 μm, respectively. This paper provides a basis for tuning microstructure and element behavior via preheating temperature optimization in laser welding of dissimilar GH4169/GH3039 for further engineering application.

The effect of interfacial alloy formation on the mechanical properties of the additively manufactured Ti6Al4V/Ti1Al8V5Fe microstructurally graded material

Multi-material (MM) structures have been shown in the past to be potential candidates for future high performance high strain rate applications. With the advancement of MM additive manufacturing (AM), there is a renewed push to explore the vast array of materials combinations to deliver advanced protective capabilities. At the same time, many fundamental issues are still plaguing MM assemblies, primarily linked to the often-poor quality of the MM interface. Here, we present a novel approach to obtain microstructural and mechanical properties gradient without interface defects by leveraging the link between the chemical composition and complex grain/phase morphology in titanium alloys. We used additive manufacturing (AM) to combine α+β-titanium alloy Ti6Al4V with metastable β-titanium alloy Ti1Al8V5Fe (which belong to different alloy classes but share common alloying elements), into a microstructurally graded material (MGM). Uniquely, the classic MM interface was replaced by the two additional intermixed alloy layers with unique chemical composition, microstructure and mechanical properties, with both ultimately making a significant contribution to the overall performance. The properties of these interface alloys are affected by many factors, such as thermal properties of the substrate, process parameters, alloying element distribution and post-manufacturing heat treatment. As a result, we showed that a superior combination of the strength and ductility could be achieved in the hybrid material after heat treatment compared to the original materials or the as-built hybrid material, which was ultimately attributed to the formation of the interface alloys. The presented approach is not limited to titanium alloys and could be extended to other materials systems and is expected to contribute to the development of a deeper understanding of the intermixing phenomena and its effects on microstructure and mechanical performance of MGMs, opening the door to a range of unique solutions in alloy and MM structural design for high performance applications.