Fe Content Research Articles

Iron doping effect on superconducting properties of FexSe0.4Te0.6 thin films

The evolution of superconductivity in FexSe0.4Te0.6 thin films (0.5 ≤ x ≤ 1.3) with Fe doping has been investigated. A thorough phase diagram of FexSe0.4Te0.6 has been established based on the transport measurements. Zero resistance can be achieved in a wide range of Fe content from 0.7 to 1.3, and the superconducting transition temperature Tc is sensitive to the chemical composition. The optimal Fe content is 0.9, illustrating that moderate Fe vacancies are conducive to improving the metallicity, effective pinning energy, and critical temperature. Nevertheless, the superconductivity is suppressed abruptly when the Fe content is further reduced. Corresponding theoretical calculations can support our experimental results well, and suggest that the variation of density of state caused by Fe vacancy is crucial for the improvement of Tc. Our study provides further insight into the mechanism of Fe content effects on tunning the superconducting properties of FexSe0.4Te0.6 thin films.

Design of non-heat-treatable Al-Fe-Ni alloys with high electrical conductivity and high strength via CALPHAD approach

Electrical conductivity and strength are two critical properties concerned for rotors materials in electric vehicles. However, the two properties are often mutually exclusive in cast Al alloys. The present work proposes a novel non-heat-treatable Al-Fe-Ni alloy by considering the intermetallic compound’s content and morphology. With the modification of Ni and Fe content, the solidification path of designed alloy were calculated to predict the phase composition, which would greatly impact their performance. The as-cast Al-2Fe-1Ni (wt%) alloy exhibits comprehensive properties with an ultimate tensile strength of 131.2±2.5 MPa, an elongation of 20.2±3.6 % and an electrical conductivity up to 52.0±0.1 %IACS. The eutectic microstructure of Al13(Fe,Ni)4+α-Al in Al-2Fe-1Ni alloy accounts for over 90 %, much larger than the eutectic content in Al-0.4Fe-3.4Ni and Al-1Fe-1Ni alloys. The fine eutectics in Al-2Fe-1Ni alloy improve the second-phase strengthening effects and plastic deformation capability. In addition, the fibrous rod-like intermetallic reduces the electron scattering during the propagation process and leaves more space for free electron movement. The dominant second phase transforms from Al3Ni phase to Al9FeNi phase, further enhancing the thermal stability of the alloy. After aging treatment at 180 °C for 100 h, it shows no noticeable change in electrical conductivity and mechanical properties. It is hoped that this work can provide a new design approach for high-strength and high-conductivity Al alloys.

An all solid waste CO2 sequestration material consist of multiple calcium silicate clinkers by carbide slag, copper tailing and red mud: Clinker crystal transformation and carbonation hardening properties

In this study, a CO2 sequestration material was obtained by all components solid wastes, i.e., carbide slag and copper tailing based on red mud (RM) as crystal regulator after a sintering and carbonation process. With the increasing dosage of RM, the mineral compositions of generated RM-modified clinkers were mainly γ-C2S (i.e., around 80 %) at low dosage RM (i.e., 3.0 %), and was gradually increased content of β-C2S (β-dicalcium silicate), C3S (tricalcium silicate) and C2AS (gehlenite) at high dosage RM (i.e., from 3.0 % to 10.0 %). Moreover, the compressive strength of various carbonated compacts made by RM-modified clinkers after CO2 curing were shows firstly increased and then decreased with a RM dosage inflection of 5.0 %. This compressive strength results should be attributed to their carbonation activity, i.e., higher carbonation activity, higher compressive strength. The obvious carbonation activity difference of various RM-modified clinkers were not simply depends on their only γ-C2S content, only β-C2S content, only C3S content or the sum of calcium silicate minerals, but more closely relate to their combined effect. This work provides a new utilization strategy of RM as crystal regulator according to its high alkaline and high Fe content composition characteristic for obtaining a CO2 sequestration materials. And also laid a new insight for a synergistic CO2 sequestration by multiple calcium silicate clinkers in the future.

Substrate and potential-driven surface morphology of bifunctional Ni-Fe electrode for efficient alkaline water electrolysis

Nickel-iron (Ni-Fe) alloy electrodes are synthesized using chronoamperometry. The influence of substrate type (copper, stainless steel, and nickel) and deposition potential on the structural, morphological, and electrocatalytic characteristics are systematically investigated. X-ray diffraction (XRD) analysis revealed the formation of a face-centered cubic (FCC) Ni-Fe alloy. Electrodeposition at higher potential (−1.45 V) forms well-defined nanoflakes, whereas electrodeposition at lower potential (−1.00 V) results aggregated Ni-Fe particles. The Ni-Fe alloy electrodes having well-defined nanoflakes demonstrated superior electrocatalytic performance, exhibiting a overpotential of −168 mV vs. RHE for the hydrogen evolution reaction (HER) and 236 mV vs. RHE for the oxygen evolution reaction (OER), at current density of 10 mA/cm2. The enhanced electrocatalytic activity of the nanoflakes based Ni-Fe alloy is attributed due to their larger catalytic surface area, porous morphology and higher Fe concentration. The Ni-Fe alloy electrodes displayed bifunctional electrocatalytic behavior, making them highly suitable for both HER and OER processes.

Enhancing the productivity and nutritional quality of lentil (Lens culinaris L.) with combined foliar application of zinc and urea

There is need to enhance the nutritional quality of lentil for ameliorating nutrient deficiencies in people especially vegetarians. The study was carried out to investigate the effect of soil application of zinc (Zn) and foliar application of Zn and nitrogen [(N) through urea] on grain yield and enrichment of grain with Zn in lentil. The field experiments were conducted at two locations Ludhiana and Faridkot, India. The experiment was consisted of eleven treatments (control, soil application of 25 kg ha−1 ZnSO4 at sowing time, foliar spray of sole 0.5% ZnSO4 or 2% urea and combined foliar spray of 0.5% ZnSO4 + 2% urea at flowering, pod formation, and flowering + pod formation stages). The foliar application of 0.5% ZnSO4 + 2% urea spray at flowering + pod formation stages significantly improved the grain yield, Zn and iron (Fe) concentration at maturity in stover and grain (whole as well as split) of lentil and protein content in stover and grain. The combined application of ZnSO4 (0.5%) + urea (2%) at flowering + pod formation stages can be done to improve not only the grain yield (on an average 29.5%) but also the Zn (49.7%) and Fe (17.4%) concentration in lentil grain, which, can help in ameliorating malnutrition in human population.

Genetic diversity study and estimation of iron and zinc content in red sorghum genotypes (Sorghum bicolor [L.] Moench)

Abstract A study involving 72 red sorghum genotypes was carried out during Rabi, 2021-22 with the objective of identifying high yielding red sorghum accessions with superior Fe and Zn content. These 72 genotypes were grouped into 10 clusters. All the four checks used in the study were grouped in cluster VIII (CO 4, Paiyur 2, Usilampatti local and AURS 013). Based on single plant yield, CO 4 was identified as the best check. Genotypes IS 29630, IS 30536 and 38 CS were grouped under cluster IX, and were better than the best check with respect to yield. These genotypes could be used in further breeding programmes. PCA identified five principal components that had Eigen value greater than one and accounted for about 72.5% of the total variation. Based on the mean performance, the genotypes viz., IS 14775, IS 29630, 38 CS, IS 29322, IS 30536, 34 CS, IS 23390, SD 8348, IS 4966 and IS 21544, which had recorded high single plant yield were used for the estimation of iron (Fe) and zinc (Zn) content. High Fe and Zn were recorded in IS 21544 and IS 4966. Keywords: Red sorghum, clustering, PCA, mean performance, Fe and Zn.

Heavy Metals Distribution in Mangrove Leaves in Various Sudanese Coastal Zones at The Red Sea

<p style="text-align:justify;"><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">Mangrove ecosystem contamination, especially in the Red Sea region, has caused major concerns on a worldwide scale. The heavy metal accumulation typical of a mangrove species, </span><em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">Avicenna marina </span></em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">L. (</span><em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">A. marina</span></em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">) leaves and soluble salts in sediments have not been studied on the Red Sea coast of Sudan.  The present study investigates the two nutrients calcium (Ca) and iron (Fe) and heavy metals such as barium (Ba), titanium (Ti), and strontium (Sr) in the mangrove species </span><em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;">A. marina</span></em><span style="font-family:"Times New Roman",serif;font-size:10.0pt;line-height:107%;"> in the leaves of six different locations in the Red Sea coastal area, as follows: (Hamasyat (HM) Keligo (KG), and Enkfel (EK) of the Gulf of Dunnabeb, and three sites were selected in the south of the Sudanese coast as follows: (Amarat Island (AM), Ibn Abbas Island (BN), and Ras Kassar (RK). The results demonstrate that the maximum calcium (Ca) and iron (Fe) concentrations in mangrove leaves were 35.9 mg/kg and 4.10 mg/kg recorded at RK and AM, respectively, in the south region of the Red Sea. The heavy metal concentrations (mg/kg) vary between different locations. The higher concentration of heavy metals in mangrove leaves increased as Ba was 1.1 mg/kg in the EG north region. While Ti (0.5 mg/kg) and Sr (2.80 mg/kg) higher concentrations were recorded in AM and EK, respectively, in the south area than in the other experimental sites.   Heavy metals and soluble salts in sediments are continuously monitored in mangrove habitats to ensure they keep within allowed limits. These results could be useful as a database for prospective ecological research, preservation efforts, and long-term sustainable management of the Sudanese mangrove ecosystems throughout the Red Sea coastal.</span></p>

Sulfate-reducing bacteria for bioremediation of sediments from constructed wetlands for acid mine drainage treatment

<p class="AbstractText"><span lang="EN-US">Sediment is a source and sink of heavy metal contaminants in wetlands. In this study, sulfate-reducing bacteria (SRB) were used for the bioremediation of sediments from wetlands affected by acid mine drainage. The sediments were inoculated with SRB </span><span lang="EN-GB">to study their influence on both the solution and sediments.</span><span lang="EN-US"> The changes of pH, electrical conductivity (EC), redox potential (Eh) values, and sulfate (SO<sub>4</sub><sup>2-</sup>), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) concentrations in the supernatant were monitored over a period of 70 days. Additionally, the variations in exchangeable, reducible, oxidizable, and residual Fe, Mn, Cu, and Zn concentrations. For the supernatant solution, the pH in all experimental groups decreased slightly within the first 14 days, increased gradually thereafter, and finally stabilized during days 35−70. The EC values and Fe and Mn concentrations displayed a similar trend with concentrations initially increasing and then decreasing. In the SRB-inoculated sediments, Fe, Mn, and Cu were gradually transformed from the exchangeable and reducible fractions to the oxidizable fraction. The inoculation with SRB reduced the ability of Fe, Mn, and Cu to migrate in sediment.</span><span style="font-family:'Times New Roman';font-size:12.0000pt;line-height:200%;mso-fareast-font-family:宋体;mso-font-kerning:1.0000pt;mso-spacerun:'yes';"><o:p></o:p></span></p><p class="MsoNormal" style="line-height:200%;"><span style="font-family:'Times New Roman';font-size:12.0000pt;line-height:200%;mso-fareast-font-family:宋体;mso-font-kerning:1.0000pt;mso-spacerun:'yes';"><o:p></o:p></span></p>

Ecological risk assessment of heavy metals contaminated mining sites of eastern india using soil and moss.

The blooming industrialization and urbanization is leading to increased mining operations. These intensified mining activities emit heavy metals into the environment, posing serious threats to ecosystems. Hence, this study focused on assessing heavy metal pollution in mining soil, utilizing mosses as bioindicators. The ecological risk, geo-accumulation factor, and contamination factor have been calculated to know the harmful effect of heavy metals on ecosystem. The study covered three distinct mining sites of eastern India within Odisha: Jajpur's Sukinda Valley (SP1, Cr), Keonjhar's Joda-Barbil (SP2, Fe and Mn), and Sundargarh's Koira-Joda (SP3, Fe). The collection of 48 soil samples through random sampling revealed significant variations in heavy metal concentrations. SP1 recorded Cr concentration of 6572 ± 445mg/kg and Ni of 8042.47 ± 501.38mg/kg, surpassing eco-toxicological levels. The storage site in SP2 exhibited the highest Fe concentration at 9872 ± 502mg/kg, and Mn levels in SP3 were at 7884 ± 432mg/kg. Storage areas in all three regions held the highest concentrations of heavy metals. Mosses in studied area demonstrated as potential bioindicators for monitoring heavy metal pollution. EF and Igeo assessments showed Cd, Pb, Hg, and other heavy metal contamination compared to earlier investigations. This study indicated higher ecological risks for Pb, As, Cu, Ni, and Zn. The Hyophila involuta accumulates Mn, Cr, Cd, Pb, Fe, and Hg, while Barbula arcuata accumulates Mn, As, and Cu in SP1. Hyophila involuta and Trematodon longicollis accumulate Mn, Cr, Cd, Pb, Fe, Hg, and Zn in SP2. Trematodon ambiguous accumulates Cd, Fe, and Ni, while Fissidens diversifolius accumulates Mn, Cr, Hg, As, Cu, and Zn in SP3. These findings emphasize the necessity of monitoring heavy metal pollution in contaminated zones using moss as a potential bioindicator.

Processing and Characterization of Spent Nickel-Metal Hydride Type AA Batteries to Recover Valuable Materials (Cobalt, Nickel and Rare Earth Elements).

The experimental research was focused on the investigation of valuable material from spent Ni-MH type AA batteries, namely the metal grid anodes and the black mass material (anode and cathode powder). The materials of interest were analyzed by X-ray fluorescence spectroscopy (XRF), ICP-OES (inductively coupled plasma optical emission spectrometry), optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). The analyzed grids have a high Fe content, but some of them correspond to the Invar alloy with approx. 40% Ni. In the black mass material, round particles and large aggregations were observed by SEM analysis, showing a high degree of degradation. The XRD analysis reveals the presence of only three compounds or phases that crystallize in the hexagonal system: La0.52Ce0.33Pr0.04Nd0.11Co0.6Ni4.4, Ni(OH)2, and La5Ni19. The obtained results provide useful and interesting information that can be used for further research in the recycling and economic assessment of metals from spent Ni-MH batteries.

Agronomic biofortification of tomatoes with iron enhances growth, yield and quality

ABSTRACT Agronomic biofortification with iron (Fe) in tomatoes has emerged as a promising strategy to combat global iron deficiency. Iron is essential for human health and plays a critical role in the growth and development of crops. This study aimed to determine the optimal dose of Fe for tomato biofortification and assess its impact on its growth, yield and quality attributes, particularly the fruit’s Fe content. A greenhouse experiment was conducted using tomato hybrids Sandal and Sahel, applying Fe foliar treatments at concentrations of 0, 1, 3, 6 and 9 mM Fe per plant. The results demonstrated that foliar application of 6 mM Fe significantly enhanced the tomato’s growth, yield and quality, while markedly increasing the fruit’s Fe content to 30.07 and 34.1 mg kg−1 in Sandal and Sahel hybrids, respectively. These values were substantially higher than those of the control treatment with Fe contents of 14.77 and 15.0 mg kg−1, respectively. However, higher doses of Fe (> 6 mM Fe per plant) showed adverse effects on growth, yield, and quality. Foliar application of iron proved an effective and economical solution, readily integrated into commercial tomato production, offering farmers a practical method to produce Fe-biofortified tomatoes and combat iron deficiency-linked malnutrition.

Structural evolution of liquid silicates under conditions in Super-Earth interiors

Molten silicates at depth are crucial for planetary evolution, yet their local structure and physical properties under extreme conditions remain elusive due to experimental challenges. In this study, we utilize in situ X-ray diffraction (XRD) at the Matter in Extreme Conditions (MEC) end-station of the Linear Coherent Linac Source (LCLS) at SLAC National Accelerator Laboratory to investigate liquid silicates. Using an ultrabright X-ray source and a high-power optical laser, we probed the local atomic arrangement of shock-compressed liquid (Mg,Fe)SiO3 with varying Fe content, at pressures from 81(9) to 385(40) GPa. We compared these findings to ab initio molecular dynamics simulations under similar conditions. Results indicate continuous densification of the O-O and Mg-Si networks beyond Earth’s interior pressure range, potentially altering melt properties at extreme conditions. This could have significant implications for early planetary evolution, leading to notable differences in differentiation processes between smaller rocky planets, such as Earth and Venus, and super-Earths, which are exoplanets with masses nearly three times that of Earth.

A slow-release reduction material of Escherichia sp. F1 coupled with micron iron powder achieves the remediation of trichloroethylene-contaminated soil

Trichloroethylene (TCE) is a prevalent organic pollutant found in soil. The oxide passivation layer on the surface of micron iron powder inhibits the release of its reducing components, leading to ineffective reduction and purification of TCE in soil. To enhance TCE degradation, a slow-release reduction material "Escherichia sp. F1-micron iron powder" was developed. A novel iron-reducing bacterium, Escherichia sp. F1, was isolated from soil contaminated with chlorinated hydrocarbons. This bacterium demonstrated a sustained iron reduction capability, achieving a reduction rate of 38.7% for Fe(Ⅲ) within 15 days. Genome sequencing revealed that strain F1 harbors 53 functional iron reduction genes and 2 dehalogenation genes. Single-factor experiments identified the optimal conditions for TCE degradation in soil using the coupling material: glucose concentration at 40 mmol/kg, soil water content at 50%, and bacterial inoculum at 1% (v:w). Under these optimal conditions, the coupled material achieved 86.86% degradation of TCE in soil within 28 days. Further analysis using X-ray photoelectron spectroscopy of micron iron powder, soil Fe(Ⅱ) concentration, and soil physicochemical properties demonstrated that the addition of strain F1 to the soil could disrupt the passivation layer of iron oxide on the surface of micron iron powder, promoting the exposure of its reactive sites and internal reducing active components. This resulted in an in situ self-actuated activation of passivated micron iron powder, leading to an improved removal rate and complete dechlorination of TCE in the soil. Soil microbial high-throughput sequencing revealed that the addition of strain F1 regulated the soil bacterial community, significantly enriching of Escherichia-Shigella species associated with iron-reducing functions. This enrichment facilitated the degradation of TCE in the soil through coupling materials. The functional material plays a crucial role in achieving green treatment and risk control of sites contaminated with chlorinated organic pollutants.

Tribological performance of used engine oil treated with cement and celite adsorbents by solvent extraction-adsorption method

Purpose As lubricating oils are used, their performance deteriorates and they become contaminated. The purpose of this paper is to investigate the lubrication performance of reclaimed 5 W-30 a fully synthetic used engine oil (UEO) with wear tests after refining it from a solvent-based extraction method using solvent (1-PrOH) and adsorbent materials such as cement, celite and deep eutectic solvent (DES). Design/methodology/approach The treated oil mixtures were prepared by blending engine oils with various adsorbent materials at 5% (w/w) in organic 1-PrOH solvent at a UEO: solvent ratio of 1:2 (w/w). The measurement of kinematic viscosity, density, the total acid number (TAN) and elemental analysis of oil samples was done by the ASTM standards D445/D446, D4052, D974 and D6595, respectively. Adsorbents and treated oil samples characterized by SEM-EDX, FTIR and UV analysis, respectively. Meanwhile, lubricating performance in tribological applications was evaluated through the wear test device using a rotating steel alloy 1.2379 cylinder and a stationary 1.2738 pin under 20, 40 and 80 kg load conditions. Worn surface analysis was done with SEM and 2.5D images. Findings It was found that when using the combination of cement and celite as an adsorbent in the reclamation of used engine oil demonstrated better lubricant properties. The properties of used engine oil were improved in the manner of kinematic viscosity of 32.55 from 68.49 mm2/s, VI (Viscosity index) value of 154 from 130, TAN of 3.18 from 4.35 (mgKOH/g) and Fe content of 11 from 32 mg/L. The anti-wear properties of used engine oil improved by at least 32% when 5% cement and 5% celite adsorbent materials were used together. Research limitations/implications The paper is based on findings from a fully synthetic 5 W-30 A5 multi-grade engine lubrication oil collected after driving approximately 12.000 km. Practical implications The results are significant, as they suggest practical regeneration of used engine oil is achievable. Additionally, blending fresh oil with reclaimed used engine oil in a 1:1 ratio reduced wear loss by over 10% compared to fresh oil. Social implications Reusing used engine oils can reduce their environmental impact and bring economic benefits. Originality/value This study showed that the properties of UEO can be enhanced using the solvent extraction-adsorption method. Furthermore, the study provided valuable insights into the metal concentrations in engine oil samples and their impact on lubrication performance. The order of the number of the grooves quantity and the possibility of the observed scuffing region trend relative to the samples was UEO > 5W-30 fresh oil > Treated oil sample with the adsorbent cement and celite together. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0209/

Refinement of microstructure and improvement of mechanical properties of directed energy deposited titanium alloys by adding Fe

Elemental alloying is a validated strategy for enhancing the mechanical properties of directed energy deposited titanium alloys. However, it is still a challenge to obtain titanium alloys with both high strength and high ductility. In this work, to balance strength and ductility, the alloying element Fe was in-situ added to the TC4 melt pool during the directed energy deposited process and the effects of its content on the microstructure and mechanical performance of the TC4 alloy deposits were investigated. The results showed that the Fe additive ranging from 0.5 to 2.0wt.% were completely solid-solved in the retained β phase of TC4 alloys. Moreover, the primary β columnar grains were transformed into fully equiaxed grains. Meanwhile, the presence of Fe refined the α-laths, increased the proportion of the retained β phase, and the continuous grain boundary α (GB-α) became discontinuous. The tensile strength of the deposited alloys was continually improved with increasing Fe content, while the elongation had a peak value. When the Fe content was 1.0wt.%, the deposited alloy exhibited the best comprehensive performance, with an ultimate tensile strength of 1071MPa and an elongation of 9.3%. The enhancement of tensile strength was attributed to the solid solution strengthening and the refinement of α-laths and primary β grains. The increased proportion of retained β phase and the formation of discontinuous GB-α were beneficial for the alloy ductility. However, increased α/β interfaces inhibited dislocation movements, resulting in a decrease in ductility. The development of this alloy is important for aerospace and other fields that require high strength, high ductility and lightweight.

Comparative study of Ni nanoparticles synthetized using electroless Ni plating waste and an analytical Ni reagent. Characterization and possible application in magnetic fluids

Wastewater from the electroless industry represents a potential danger to the environment and health, mainly due to its heavy metal content. In this study, nickel nanoparticles were synthesized through chemical reduction precipitation by using an electroless nickel plating waste and hydrazine sulfate as reducing agent. The aim of the present work is twofold. First we want to extract the metal from the aqueous medium, minimizing its content to levels allowed by environmental regulations. Second, we aim to valorize the residue by recovering the precipitated nickel to be applied as a solid phase in a magnetic fluid (MF). It is found that the present synthesis method using N2H4 as reducing agent, allowed us to minimize the Ni concentration in the aqueous waste in 97.49 %. The properties of the recovered Ni precipitate is compared with the Ni nanoparticles (NPs) obtained from a solution prepared with analytical grade nickel sulfate. The synthesized materials from both the waste (Ni-R) and analytical reagent (Ni-A) were characterized by comparing their chemical, physical, and morphological properties. In both cases, the Ni-R and Ni-A precipitates, spherical Ni NPs of 8–10 nm crystallite sizes are obtained, agglomerated in a bimodal size distribution centered at 174.6 and 383.4 nm, and a monomodal size distribution centered at 63.6 nm, respectively. Both Ni precipitated samples are ferromagnetic, but the Ni-R sample has a higher magnetic saturation of 40 emu/g compared to 8 emu/g of the Ni-A sample. The difference in the rheological behavior of both precipitates could be attributed to the presence of surface oxidation having a relatively less contribution in the case of the Ni-R particles due to the higher average size of the particles. The Fe content, probably coming from the nickel-plated parts in spent baths, is slightly higher in the Ni-R sample. Thus, the present work shows that it is possible to valorize an industrial Ni-based residue, by obtaining Ni precipitates that in magnetic fluids give even better results than those expected under more rigorous experimental conditions, i.e., in cases where the quality of the chemical precursors is usually a determining factor.

Tailoring sub-5 nm Fe-doped CeO2 nanocrystals within confined spaces to boost photocatalytic hydrogen evolution under visible light

This work aimed to study the efficiency of the reverse micelle (RM) preparation route in the syntheses of sub-5 nm Fe-doped CeO2 nanocrystals for boosting the visible-light-driven photocatalytic hydrogen production from methanol aqueous solutions. The effectiveness of confining precipitation reactions within micellar cages was evaluated through extensive physicochemical characterization. In particular, the nominal composition (0–5 mol% Fe) was preserved as ascertained by ICP-MS analysis, and the absence of separate iron-containing crystalline phases was supported by X-ray diffraction. The effective aliovalent doping and modulation of the optical properties were investigated using UV-Vis, Raman, and photoluminescence spectroscopies. 2.5 mol% iron was found to be an optimal content to achieve a significant decrease in the band gap, enhance the concentration of oxygen vacancy defects, and increase the charge carrier lifetime. The photocatalytic activity of Fe-doped CeO2 prepared at different Fe contents with RM preparation was studied and compared with undoped CeO2. The optimal iron load was identified to be 2.5 mol%, achieving the highest hydrogen production (7566 μmol L−1 after 240 min under visible light). Moreover, for comparison, the conventional precipitation (P) method was adopted to prepare iron containing CeO2 at the optimal content (2.5 mol% Fe). The Fe-doped CeO2 catalyst prepared by RM showed a significantly higher hydrogen production than that obtained with the sample prepared by the P method. The optimal Fe-doped CeO2, prepared by the RM method, was stable for six reuse cycles. Moreover, the role of water in the mechanism of photocatalytic hydrogen evolution under visible light was studied through the test in the presence of D2O. The obtained results evidenced that hydrogen was produced from the reduction of H+ by the electrons promoted in the conduction band, while methanol was preferentially oxidized by the photogenerated positive holes.

An evaluation of the analytical and biological robustness of a method for quantifying iron in individual red blood cells via single-cell tandem ICP-mass spectrometry

This work evaluated the analytical and biological robustness of iron (Fe) determination in individual red blood cells (RBCs) via single-cell ICP-MS (SC-ICP-MS). RBCs were separated from other whole blood constituents using Ficoll-Paque™ density gradient centrifugation. While fixation with paraformaldehyde (PFA) led to RBC lysis, the use of glutaraldehyde (GA) left the RBCs intact and permitted storage of RBC cell suspensions in ultra-pure water for up to 16 months at 4 °C. GA-fixation also rendered the RBCs sufficiently robust to maintain integrity during their introduction into the ICP by means of nebulization of dilute suspensions. Obtaining quantitative data on a cell-per-cell basis required determination of the transport efficiency using the particle size method and external calibration against aqueous Fe standard solutions. The average Fe content per RBC obtained using SC-ICP-MS (average value of 103 fg/cell) agreed well with the value obtained using solution-based ICP-MS obtained after cell pellet digestion and with values obtained from literature. Variation of the cell number density in the suspensions analyzed between 1.5 × 105 and 6.0 × 105 cells per mL did not affect the result. Identical results from one-week interval blood drawings from healthy individuals demonstrate biological consistency. Compared to bulk analysis, the SC-ICP-MS approach offers the added value of providing information on the cell-to-cell heterogeneity in Fe content.

Time-dependent redistribution of soil arsenic induced by transformation of iron species during zero-valent iron biochar composites amendment: Effects on the bioaccessibility of As in soils

Zero-valent iron biochar composites (ZVI/BC) are considered as effective amendments for arsenic (As)-contaminated soils. However, the mechanisms of transformation of various soil As species during ZVI/BC amendments remain unclear. This study investigated As transformation in four soils (namely, GX, ZJ, HB, and HN) treated with ZVI/BC for 65 days under two soil moisture conditions, unsaturated and oversaturated. Results showed that the 65-day treatment was divided into two stages based on the variation of labile As content. Within 2 days (stage 1), ZVI/BC addition quickly reduced labile As content by 5.91–90.3 % in soils under unsaturated conditions. During days 2–65 (stage 2), labile As ultimately decreased by 0.06–0.31 mg/kg in GX, ZJ, and HB while increasing by 22.1 mg/kg in HN soil, due to its lower pH value and Fe content. The variations of labile As were attributed to changes in multiple Fe minerals and associated As species. In stage 1, the corrosion of ZVI/BC generated amorphous Fe oxides to immobilize labile As, resulting in the accumulation of meta-stable As. In stage 2, amorphous Fe oxides were transformed into crystalline Fe oxides, resulting in the release and re-precipitation of As along with transformation, thus redistributing immobilized As into labile and stable As, which was evidenced by multiple methods, including chemical extraction, XRD, and TEM-EDX. The elevated soil moisture condition would enhance the corrosion of ZVI/BC in stage 1, further forming a reductive environment to facilitate the transformation of Fe minerals in stage 2. Besides, As bioaccessibility in soils was reduced by 10.8–38.7 % after ZVI/BC treatment in in-vitro gastrointestinal simulations. Overall, our study revealed the time-dependent transformation mechanism of soil As species and associated Fe minerals under different soil moisture with ZVI/BC treatments, and highlighted the effectiveness of ZVI/BC as a long-term amendment for As-contaminated soils.

The mechanism of dolomitization in a stromatolite mound in the late Cambrian Chaomidian Formation, Shandong Province, China

Clarifying the mechanism of dolomitization is of pivotal importance and represents a burning issue among geologists. A comprehensive model to define the genesis of dolomitization in the Cambrian Chaomidian Formation carbonates is still lacking. In the highly focused study, the advanced integration of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), clumped isotope and carbon/oxygen isotope analyses was used to reveal complex interactions between the genesis and dolomitization of a stromatolite mound in the late Cambrian Chaomidian Formation of China. The results show that the dolomite content increases from bottom to top, along with a shift in lithology from limestone to dolostone. Additionally, as we moved from the base to the summit of the stromatolite mound, the Fe, Mn, and Na contents increase with increasing Mg levels, whereas the δ13C and δ18O values became more positive. Conversely, the levels of Sr and total rare earth elements (REEs) gradually decreased. The dolomite grains in the stromatolite mound are micritic and euhedral to subhedral, with foggy cores and bright edges and low cation ordering. The stromatolite limestone, dolostone, and underlying lime mudstone samples exhibit similar REE patterns: light REE enrichment, heavy REE loss, negative δEu anomalies, and weak negative δCe anomalies. The δ13C and δ18O values fall within the late Cambrian seawater range, suggesting that dolomitizing fluids originated mainly from concentrated seawater and migrated from top to bottom. The δ18O values indicate lower dolomite formation temperatures than calcite formation temperatures, supporting dolomitization during the penecontemporaneous diagenetic stage. Petrographic evidence reveals the presence of pyrite, indicating sulfate-reducing bacterial activity during diagenesis. XPS analysis revealed similar organic functional groups in both the stromatolite limestone and the dolostone, including C-(C = O)-O, C–C/C-(C–H), C-O and C-N. However, the dolostone spectrum exhibited a larger C-OH/C-O peak area, suggesting significant microbial organic matter involvement in dolomite formation. While a kinetic obstacle is recognized as a primary cause of dolomite formation, this study also suggested that microbial activity weakened this obstacle during diagenesis. Thus, microbial metabolism or cyanobacterial decomposition facilitates dolomite formation during the penecontemporaneous diagenetic stage.