Fe Ratio Research Articles

Enhancing Chemotherapy of p53‐Mutated Cancer through Ubiquitination‐Dependent Proteasomal Degradation of Mutant p53 Proteins by Engineered ZnFe‐4 Nanoparticles

AbstractA significant percentage of human cancers harbor missense mutations in the TP53 gene and express highly stabilized mutant p53 protein (mutp53) with tumor‐promoting gain‐of‐function (GOF) properties. Inducing mutp53 degradation is a viable precision anti‐tumor therapeutic strategy. Based on the previously reported finding that a zinc‐curcumin compound induced mutp53 degradation, a series of ZnFe nanoparticles (ZnFe NPs) are synthesized and it is found that ZnFe‐4, with an Zn:Fe ratio of 1:2, exhibits outstanding mutp53‐degrading capability. ZnFe‐4 induced ubiquitination‐mediated proteasomal degradation of several different mutp53 species, but not the wild‐type p53 protein. Cellular internalization, intracellular Zn++ elevation and increased ROS are all necessary for ZnFe‐4‐induced mutp53 degradation. Degradation of mutp53 by ZnFe‐4, abrogated mutp53‐manifested GOF, leading to increased p21 expression, cell cycle arrest, reduced cell proliferation and cell migration, and cell demise. ZnFe‐4 also sensitized to cisplatin‐elicited killing in p53 S241F ES‐2 ovarian cancer cells, and dramatically improved the therapeutic efficacy of cisplatin in a subcutaneous ES‐2 tumor model. The potential clinical utility of ZnFe‐4 is further demonstrated in an orthotopically‐implanted p53 Y220C patient‐derived xenograft (PDX) breast cancer model. ZnFe‐4 is the first reported mutp53‐degrading nanomaterial, and further materials engineering may lead to the development of zinc‐based nanoparticles with minimal toxicity and maximized mutp53‐degrading capability.

Experimental study on Fenton oxidation regeneration of adsorbed toluene saturated activated carbon

ABSTRACT In this study, Fenton reagent has been adopted to oxidize and regenerate the resin based spherical activated carbon (SAC) adsorbed with toluene saturation. The effects of the mole ratio of Fe2+ and H2O2, the dosage of H2O2, pH value, temperature, regeneration time and the like on the regeneration rate of activated carbon have been exploited, the adsorbent used in the experiment is spherical activated carbon with a maximum adsorption capacity of 512.25 mg/g produced by Cui hong Taiyuan Science and Technology Co. The results show that the highest regeneration rate of activated carbon can reach 95.69%. The optimal regeneration condition is that the molar ratio of Fe2+ and H2O2 is 1/25, the concentration of H2O2 is 175 mmol/L, the pH is 2, the temperature is 20℃∼30℃, and the regeneration time is 180 min. The influence of regeneration process on the characterization of activated carbon has been studied by BET analysis as well as SEM analysis.

Enhancements in catalytic activity and duration of PdFe bimetallic catalysts and their use in direct formic acid fuel cells

The palladium–iron based bimetallic catalysts (PdxFey/Cs) and facile synthetic method are introduced to enhance the catalytic activity and operational duration for direct formic acid fuel cells. To improve the properties of PdxFey/C catalysts, such as degree of PdFe alloy and its crystallinity, heat treatment is conducted at 600°C. According to results, the Pd–Fe bond and Fe metal particle are formed after the heat treatment, while iron oxides and Pd particles are observed in the untreated samples. Electrochemical evaluations for measuring the formic acid oxidation reaction rate demonstrates heat treated Pd3Fe1/C (HT-Pd3Fe1/C) is the best catalysts of six samples which are synthesized by using different Pd to Fe ratios (3:1, 1:1, 1:3) before and after heat treatment. This is because the HT-Pd3Fe1/C has high Pd–Fe alloying and Pd contents. Through the heat treatment, the indirect formic acid oxidation reaction way is activated and the resistance to CO poisoning is significantly improved. The maximum power density of direct formic acid fuel cells using HT-Pd3Fe1/C whose open circuit voltage is 0.83V is 137mWcm−2, which is 1.6 and 1.9 times higher than that of direct formic acid fuel cells using untreated catalyst and Pd/C.

Characterization of Kemer L4 meteorite using Raman spectroscopy, X-ray diffraction, magnetization measurements and Mössbauer spectroscopy.

The bulk interior of Kemer L4 ordinary chondrite was characterized for the first time by means of optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, magnetization measurements and Mössbauer spectroscopy with a high velocity resolution. The main and minor iron-bearing phases were found as well as ferrihydrite as a result of weathering. The Fe2+ partitioning among the M1 and M2 sites in olivine, orthopyroxene and clinopyroxene was determined from the X-ray diffraction. The ratios of Fe2+ occupancies for these crystals were estimated from both X-ray diffraction and Mössbauer spectroscopy data and appeared to be in a good agreement. The distribution coefficients KD and the temperatures of equilibrium cation distribution Teq were also evaluated for olivine and orthopyroxene from two independent techniques and were in a good consistence: KD=1.77, Teq=441K (X-ray diffraction) and KD=1.77, Teq=439K (Mössbauer spectroscopy) for olivine and KD=0.10, Teq=806K (X-ray diffraction) and KD=0.09, Teq=787K (Mössbauer spectroscopy) for orthopyroxene. The fusion crust of Kemer L4 was studied using X-ray diffraction, magnetization measurements and Mössbauer spectroscopy. Magnesioferrite and probably maghemite were found in the fusion crust in addition to other phases observed in the bulk interior.

Degradation of methylene blue dye under dark and visible light conditions in presence of hybrid composites of nanostructured MgFe2O4 ferrites and oxygenated organic compounds

Nanostructured MgFe2O4 ferrites of crystallite sizes 7−16 nm synthesized by either autocombustion or polymerization methods were employed as catalysts in the degradation of methylene blue (MB) dye under dark and light irradiation conditions. The Mg-ferrites were characterized by XRD, atomic absorption, SEM, BET surface, thermogravimetric analysis, Mössbauer spectroscopy and magnetometry. All the catalysts can be described as hybrid composites of Mg-ferrites (with a 1:2 Mg:Fe ratio) and residual organic compounds coming from the precursors, whose band gap energy is in the visible region (Eg ∼ 2.3 eV). The magnetic responses at ambient temperature correspond to a soft material composed by the combination of superparamagnetic and blocked particle moments. The degradation of MB occurs under both dark and light conditions only when the catalyst is incorporated to the aqueous solution. The largest degradation efficiency percentages (PDE%) achieved after an interval of 35 min are around 60 and 75 % under dark and light conditions, respectively. In the presence of visible light, the efficiency of the catalysts is enhanced in a percentage that depends on the surface area of the ferrite particles. The role of organic residues as well as the exposed surface area in the catalytic process are analysed.

Mineral chemistry of gahnite from the Lalor metamorphosed VHMS deposit, Snow Lake, Manitoba

ABSTRACTGahnite (ZnAl2O4) is a common accessory mineral at the Lalor auriferous Zn-Cu metamorphosed VHMS deposit (Snow Lake, Manitoba). To evaluate factors influencing its crystal chemistry, gahnite representing a range of textures, host mineral assemblages, and whole-rock compositions were analyzed for major, minor, and trace elements. The analyzed grains span the range of Ghn63-75Her15-22Spl10-18 and are un-zoned with respect to Zn, Fe, and Mg. A moderate positive correlation exists between Mg in gahnite and whole-rock MgO (R2 = 0.66). The minor- and trace-element chemistry of the Lalor gahnite is dominated by Mn (400–2600 ppm), Si (<25–250 ppm), and V (<25–2300 ppm). Based on the limited variability in gahnite major-element composition, as well as similar partitioning coefficients of Zn and Fe between sphalerite-gahnite pairs (indicating comparable metamorphic conditions of crystallization for the analyzed gahnite), metamorphic grade is interpreted to have had the strongest influence on gahnite major-element chemistry. Most sphalerite occurs with pyrite and pyrrhotite, an assemblage that would have buffered fS2 and fixed the Zn:Fe ratio in sphalerite, which also could have contributed to the narrow compositional range observed in gahnite. Magnesium was not an essential component of the sphalerite-consuming, gahnite-producing reactions, so its concentration in gahnite was more readily affected by whole-rock Mg. A small proportion of gahnite grains may have formed from the destabilization of silicates (staurolite and biotite), rather than sphalerite. These possible gahnite-forming reactions (sphalerite- versus biotite- or staurolite-consuming) appear to have had the strongest control on gahnite minor- and trace-element chemistry, as gahnite formed from sphalerite desulfidation reactions shows a range in Mn (450–2600 ppm) and restricted V/Mn values (<0.5), while gahnite interpreted to have formed from the dehydration of biotite and staurolite shows restricted Mn (<430 ppm) and a range of V/Mn values (0.75–5.5). Further work is recommended to investigate the possibility of using gahnite trace-element signatures (such as with Mn and V) to discriminate between gahnite that crystallized in sphalerite-rich and sphalerite-barren environments, as this concept has potential for application to exploration using detrital gahnite.

Versatile seed-mediated method of CoxFe3-xO4 nanoparticles synthesis in glycol media via thermal decomposition

Series of CoxFe3-xO4 with x = 0.0, 0.5 and 1.0 were synthesized by novel seed-mediated method in glycol media. Nanoparticles gradually change their structure from monocrystalline seeds of 6–7 nm size to polycrystalline nanoclusters of 26–33 nm size while crystallite size grows from 5 to 6 nm to 8–10 nm. All series of initial seeds as well as subsequent iron oxide nanoparticles show superparamagnetic behavior whereas other 1st and 2nd series with x = 0.5 and 1.0 show ferrimagnetic behaviour. Coercitive force of Co0.5Fe2.5O4 have comparable or even higher values than CoFe2O4 while saturation magnetization value close to iron oxide samples of same size. The proposed method may be perspective for synthesis of ferrites with controlled size, structure and Co to Fe ratio.

Study on the Possible Error Due to Matrix Interaction in Automated SEM/EDS Analysis of Nonmetallic Inclusions in Steel by Thermodynamics, Kinetics and Electrolytic Extraction

Up to now, the Fe content of nonmetallic particles has often been neglected in chemical evaluations due to the challenging analysis of matrix elements in nonmetallic inclusions (NMI) in steel by scanning electron microscope and energy dispersive spectroscopy analysis (SEM/EDS). Neglecting matrix elements as possible bonding partners of forming particles may lead to inaccurate results. In the present study, a referencing method for the iron content in nonmetallic inclusions in the submicrometer region is described focusing on the system Fe-Mn-O. Thermodynamic and kinetic calculations are applied to predict the inclusion population for different Fe/Mn ratios. Reference samples containing (Fe,Mn)-oxide inclusions with varying Fe ratios are produced by manganese deoxidation in a high-frequency induction furnace. Subsequent SEM/EDS measurements are performed on metallographic specimens and electrolytically extracted nonmetallic inclusions down to 0.3 µm. The limits of iron detection in these particles, especially for those in the submicrometric regime, as well as the possible influence of electrolytic extraction on Fe-containing oxide particles are examined. The measured inclusion compositions correlate well with the calculated results regarding segregation and kinetics. The examinations performed are reliable proof for the application of SEM/EDS measurements to evaluate the Fe content in nonmetallic inclusions, within the physical limits of polished cross-section samples. Only electrolytic extraction ensures the determination of accurate compositions of dissolved or bonded matrix elements at smallest particles enabling quantitative particle descriptions for submicrometric (particles ≤ 1 µm) steel cleanness evaluations.

Fischer–Tropsch Product Selectivity Modulation via an FeRh Nanocluster Composition Design

The reaction mechanism of *CHx formation in Fischer–Tropsch synthesis on various FeRh nanoclusters is studied using DFT calculations. We find that the energy barrier of *CH2 formation from hydrogen-assisted *CH2O dissociation can be directly modulated using the Fe/Rh composition ratio. Thermodynamic investigations and the natural bond orbital (NBO) analysis indicate that the barrier dropping of C–O bond scission in *CH2O can be ascribed to the interaction between the Fe and the O atoms. In particular, the *CH2 formation can be selectively stabilized with respect to the *CH3O formation using a local tri-Fe configuration on the FeRh nanocluster when the Fe ratio exceeds 50%. An optimal barrier may be achieved by carefully balancing the number of Rh and Fe atoms in the local configuration of the active site to stabilize both ends of the intermediates.

Cesium removal using acid- and base-activated biotite and illite

Biotite and illite have excellent cesium (Cs) adsorption capacity due to their negative charges in addition to adsorption sites of the planar, interlayer, and frayed edge sites (FES). The aim of this study is to investigate the Cs adsorption capacity using acid- and base-activated biotite and illite based on their mineralogical characteristics. The acid-activated biotite and base-activated illite exhibited high Cs removal efficiency from the low-level Cs-containing DI water (97.5 % and 97.3 %, respectively). The acid-activation of biotite increased the specific surface area (SSA, 12.08 → 43.04 m2/g), Fe(III)/Fe(II) ratio (0.56 → 0.76), and wedge zone d-spacing (1.017 → 1.065 nm), while the zeta potential (-4.06 → -4.82 mV) decreased. The base-activation of illite resulted to a decrease in the SSA (22.14 → 18.49 m2/g), zeta potential (-7.68 → -31.64 mV), and Fe(III)/Fe(II) ratio (0.92 → 0.79). However, only acid-activated biotite appeared to have a high capacity of Cs removal from Cs-containing seawater (73.9 %; base-activated illite: 26.1 %). These results indicate that the FES of biotite owing to acid-activation showed better results in regards to Cs adsorption as compared to the pH-dependent negative charges of the base-activated illite.

Immobilizing magnetite onto quartz sand for chromium remediation

Magnetite nanoparticles are often promoted as remediation agents for heavy metals such as chromium due to their reactivity and high surface area. However, their small size also makes them highly mobile increasing the risk that reacted pollutants will be transported to different locations rather than being safely controlled. Released to aquatic environments, aggregation leads to a loss of their nano-specific properties and contaminant-removal capacity. We immobilized magnetite onto sand to overcome these issues whilst maintaining reactivity. We compare biogenic magnetite and abiogenic magnetite coated sand against magnetite nanoparticles. Magnetite coatings mostly exhibited a Fe(II)/Fe(III) ratio close to stoichiometry (0.5). We tested the efficacy of the magnetite-coated sand to adsorb chromium, with respect to biogenic/abiogenic nanoparticles. Langmuir-type sorption of Cr(VI) onto magnetite (4.32 mM total Fe) was observed over the tested concentration range (10–1000 μM). Biogenic nanoparticles showed the highest potential for Cr(VI) removal with maximum adsorption capacity (Qmax) of 1250 μmol Cr/g Fe followed by abiogenic nanoparticles with 693 μmol Cr/g Fe. All magnetite coated sands exhibited similar sorption behavior with average Qmax ranging between 257−471 μmol Cr/g Fe. These results indicate coating magnetite onto sand may be more suitable than free nanoparticles for treating environmental pollutants such as chromium.

Visible light promoted Fe3S4 Fenton oxidation of atrazine

We demonstrate that visible light irradiation can promote Fe3S4 Fenton oxidation of atrazine. The visible light irradiation could increase the atrazine Fenton degradation rate by 4.9 times. The enhanced atrazine degradation activity under visible light was attributed to the higher surficial Fe(II)/Fe(III) ratio of Fe3S4 and the efficient surface iron redox cycle triggered by visible light. Experimental results revealed that the operando formation of FeOOH on the Fe3S4 surface blocked the iron redox cycle and inhibited the H2O2 decomposition, accounting for the largely decreased Fenton activity of Fe3S4 in dark, while these problems were successfully solved by the introduction of visible light irradiation, which excite Fe3S4 to produce abundant photo-generated electrons and O2− for efficient regeneration of active Fe(II) species of Fe3S4 and in-situ formed FeOOH.

Enhanced magnetization of ultrathin NiFe2O4 films on SrTiO3(001) related to cation disorder and anomalous strain

NiFe$_2$O$_4$ thin films with varying thickness were grown on SrTiO$_3$(001) by reactive molecular beam epitaxy. Soft and hard x-ray photoelectron spectroscopy measurements reveal a homogeneous cation distribution throughout the whole film with stoichiometric Ni:Fe ratios of 1:2 independent of the film thickness. Low energy electron diffraction and high resolution (grazing incidence) x-ray diffraction in addition to x-ray reflectivity experiments were conducted to obtain information of the film surface and bulk structure, respectively. For ultrathin films up to 7.3 nm, lateral tensile and vertical compressive strain is observed, contradicting an adaption at the interface of NiFe$_2$O$_4$ film and substrate lattice. The applied strain is accompanied by an increased lateral defect density, which is decaying for relaxed thicker films and attributed to the growth of lateral grains. Determination of cationic site occupancies in the inverse spinel structure by analysis of site sensitive diffraction peaks reveals low tetrahedral occupancies for thin, strained NiFe$_2$O$_4$ films, resulting in partial presence of deficient rock salt like structures. These structures are assumed to be responsible for the enhanced magnetization of up to $\sim$250\% of the NiFe$_2$O$_4$ bulk magnetization as observed by superconducting quantum interference device magnetometry for ultrathin films below 7.3 nm thickness.

Data supporting the results of the characterization of the phases and structures appearing during the synthesis process of Ba0.5Sr1.5Zn2-xNixFe12O22 by auto-combustion.

The data presented has to do with identifying the various phases arising during the synthesis of the Y-type hexaferrite series Ba0.5Sr1.5Zn2-xNixFe12O22 by auto-combustion that we deem important for their microstructural and magnetic properties. The data and the related analyses support the research paper “Ni-substitution effect on the properties of Ba0.5Sr1.5Zn2-xNixFe12O22 powders” [1]. Thus, the parameters are presented of the phases appearing after auto-combustion and after the initial annealing at 800 °C, namely, crystal cell and crystallite size. Also, additional data are provided obtained by EDS concerning the Ba:Sr:Zn:Ni:Fe ratio in Ba0.5Sr1.5Zn2-xNixFe12O22 (x = 0.8, 1, 1.5) samples synthesized at 1170 °C for 10 h. The data can be used as a reference in establishing how the phases distinguished during the initial process of auto-combustion affect the Ba0.5Sr1.5Zn2-xNixFe12O22 powders, which are candidates for room-temperature multiferroic materials. The data have not been published previously and are made available to permit critical or further analyses.

Study on influencing factors and mechanism of removal of Cr(VI) from soil suspended liquid by bentonite-supported nanoscale zero-valent iron

In order to clarify the mechanism and effect of bentonite-supported nanoscale zero-valent iron (nZVI@Bent) on Cr(VI) removal in soil suspended liquid, nZVI@Bent was prepared by liquid-phase reduction method in this research. A number of factors, including the mass ratio of Fe2+ to bentonite during preparation of nZVI@Bent, nZVI@Bent dosage, soil suspended liquid pH value and reaction temperature were assessed to determine their impact on the reduction of Cr(VI) in soil suspended liquid. The nZVI@Bent was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to analyze the mechanism of removal of Cr(VI) from the soil. The results showed that the temperature of soil suspended liquid had a significant effect on the removal efficiency. Calculated by the Arrhenius formula, nZVI@Bent removes Cr(VI) from the soil suspended liquid as an endothermic reaction with a reaction activation energy of 47.02 kJ/mol, showed that the reaction occurred easily. The removal of mechanism Cr(VI) from the soil by nZVI@Bent included adsorption and reduction, moreover, the reduction process can be divided into direct reduction and indirect reduction. According to XPS spectrogram analysis, the content of Cr(III) in the reaction product was 2.1 times of Cr(VI), indicated that the reduction effect was greater than the adsorption effect in the process of Cr(VI) removal. The experiment proved that nZVI@Bent can effectively remove Cr(VI) from soil suspension, and can provide technical support for repairing Cr(VI)-polluted paddy fields.

Efficient degradation of indigo wastewater by one-step electrochemical oxidation and electro-flocculation

Purpose Indirect electrochemical oxidation and electro-flocculation were combined to degrade indigo wastewater. Design/methodology/approach The degradation efficiency of indigo wastewater in single-cell and double-cell were investigated. Based on the previous single factor experiments, the oxidative degradation conditions of indigo wastewater in single cell were optimized by response surface methodology (RSM). The decolorization rate, chemical oxygen demand (COD) removal rate, the contents of flocculation precipitation and indigo were measured and analyzed. Findings The degradation efficiency in single cell was higher than in double cell. The electrolysis conditions were optimized by RSM and the decolorization rate was 99.01% with COD removal rate of 60.34% and conductivity of 89.75 mS/cm. The amount of flocculated precipitation decreased by 53.33% and the indigo increased by 86.34%. The content of Na and S decreased by 12.13 and 6.49%, respectively. The ratio of Fe3+ to Fe2+ in the solution was 4.62:1, indicating that most of the iron dropped on the electrode sheet was converted to Fe3+. Research limitations/implications The one-step electrochemical oxidation and flocculation method with the advantages of simple operation and environmental protection, provided a reference for the actual treatment of dyeing wastewater. Practical implications Combining the electrochemical flocculation and oxidation provided an efficient and practical solution for degradation of indigo wastewater. Originality/value Combining the advantages of electrochemical oxidation and electroflocculation, the application of electrochemistry in printing and dyeing wastewater treatment technology has been expanded.

Citrate Controls Fe(II)-Catalyzed Transformation of Ferrihydrite by Complexation of the Labile Fe(III) Intermediate.

Ferrihydrite (Fh) is generally associated with dissolved organic matter (DOM) in natural environments due to a strong sorption affinity at circumneutral pH and its high specific surface area. In suboxic conditions, aqueous Fe(II) (Fe(II)aq) can catalyze transformation of Fh into more stable crystalline Fe(III) phases, but how DOM influences the transformation kinetics and pathway is still unclear. Using citrate as a surrogate, we have examined Fh transformation with 1 mM Fe(II)aq and 0-60 μM citrate at pH 7.2. We focus on quantifying the time-dependent concentrations of sorbed Fe(II), structural Fe(II), and a key intermediate species, labile Fe(III) (Fe(III)labile), resulting from interfacial electron transfer (IET), and how these species correlate with the evolution of lepidocrocite (Lp), magnetite (Mt), and goethite (Gt) products. Low concentrations of citrate significantly impact the proportions of Lp/Gt, and the collective results reveal that its effect is primarily through its ability to complex labile Fe(III) and thereby disrupt polymerization into product crystallites, as opposed to modifying the surface properties of Fh or inhibiting IET. The emergence of a Mt coprecipitate is observed in the transformation experiments with 5-10 μM citrate, when the Fe(II)/Fe(III)labile ratio on/near the Fh surface is close to 0.5, the stoichiometric Fe(II)/Fe(III) ratio in Mt. At the molecular level, the findings suggest that citrate, and by extension DOM, can modify the relative rates of olation and oxolation reactions that assemble labile Fe(III) into various product minerals.

Pedogenesis of bleached topsoils occurring on weakly structured, high chroma subsoils in South Africa

Topsoil bleaching is a common occurrence in South African soils. Bleaching is usually associated with the removal of soil pigmenting agents through redox stripping, clay eluviation and/or podzolisation. Thus topsoil bleaching above non-podzolic, high chroma red and yellow, supposedly well-drained subsoils is difficult to explain. These deep, weakly structured, red and yellow subsoils are some of the best agricultural soils in the country, and when climate allows, are farmed intensively. Bleached topsoils are known for their unfavourable physical characteristics, therefore understanding how these soils form is important to guide their taxonomic discrimination so that they can be managed sustainably.Profiles showing bleached and non-bleached (high chroma) topsoils were sampled from two different geographical regions; the summer rainfall eastern Highveld region and the winter rainfall, Western Cape Boland region. These samples were statistically compared to identify differences between bleached and non-bleached variants. Topsoil bleaching was shown to be hydrologically driven in catenal sequences in the summer rainfall region. In the red – yellow – grey topographic sequence, subsoil colour changes lag behind topsoil colour changes resulting in a zone where bleached topsoils overly high chroma yellow subsoils. The significantly higher (p = 0.05) acid oxalate/citrate dithionite bicarbonate Fe ratio (Far) in bleached topsoils adds further evidence to a redox driven system. Bleached profiles from the Highveld show indicators of increased subsoil clay accumulation, but it is proposed this is not a dominant process and is likely to be a result rather than the cause of bleaching.Bleaching mechanisms in the Western Cape are harder to establish. Only water dispersible clay differs significantly (p = 0.01) between bleached and non-bleached variants. Extractable Fe fractions do not provide significant evidence of redox pathways, although Far is slightly higher in bleached topsoils, despite a lower absolute oxalate extractable Fe concentration. Although not significant (p = 0.11), exchangeable Na, is higher in the bleached profiles and this may account for the more dispersible nature of the bleached profiles. These results suggest that topsoil bleaching in the Western Cape red apedal soils should be used as an indicator for poor structural stability and that these soils require more stringent management to prevent degradation.

Occurrence and Composition of Columbite-(Fe) In the Reduced A-Type Desemborque Pluton, Graciosa Province (S-SE Brazil)

Columbite-(Fe) is a post-magmatic accessory mineral occurring within syenogranites and greisens from the Desemborque Pluton. The petrographic (SEM) and geochemical (EPMA and LA-ICPMS) examination of this mineral shows two distinct textural types within both the rocks, named columbite-1 and columbite-2. The columbite-1 type is characterized by zoned crystals with two stages of crystallization: i) An early Nb-rich cores with low Ta/(Ta + Nb) and Mn/(Mn + Fe) ratios (0.02–0.08 and 0.17 to 0.21 apfu, respectively), and ii) a later Ta-rich rims with higher Ta/(Ta + Nb) ratios (0.11–0.26) and similar Mn/(Mn + Fe) ratios (from 0.14 to 0.22) relative to the former cores. On the other hand, the columbite-2 type is defined by irregular crystals with patchy textures and very low Ta/(Ta + Nb) ratios (0.008–0.038) and moderate Mn/(Mn + Fe) ratios between 0.20 and 0.38. Trace element compositions of all columbite-(Fe) crystals are relatively enriched in HREEs and HFSEs; however, the columbite-2 presents higher abundances of REEs, Y, Th, U, Pb, Sc, and Sn relative to the columbite-1. This study highlights a unique hydrothermal origin for both the columbite types, but the textural relations of the columbite-2 crystals indicated that its formation is related to fluid-induced alterations of post-magmatic fluorite and/or cassiterite crystals at the final stage of the post-magmatic evolution.

Mechanism of the Elution of Iron from a Slag-Compost Fertilizer for Restoring Seaweed Beds in Coastal Areas-Characteristic Changes of Steelmaking Slag and Humic Acids Derived from the Fertilizer during the Elution Process.

The characteristic changes in steelmaking slag and humic acids (HAs) derived from a slag-compost fertilizer and their relation to the elution of Fe were evaluated in tank tests in Mashike, Hokkaido and Tsushima, Nagasaki. Analyses of iron, nitrogen and phosphate in the eluate, changes in the chemical states on the surface of the steelmaking slag, and the macro-structural features of the isolated HAs were investigated during the test. Temporal changes in Fe concentrations in the tanks were consistent with data collected in previous studies. Analyses of the surface by 57Fe Mössbauer spectroscopy showed that the concentration of Fe2+ in the fertilizer decreased and the ratio of Fe3+ increased, indicating that Fe2+ was preferentially eluted from the slag surface. The yields of HAs were significantly decreased during the test when steelmaking slag was mixed with compost. Changes in the UV-vis absorptivities indicated that de-aromatization had occurred. These results indicate that microorganisms that were present under these experimental conditions became activated by the mixing of compost with steelmaking slag, and are closely related to the continuous elution of Fe. The residual Fe in the fertilizer after the tests was investigated by analyzing seawater and the levels of extractable Fe. The trends for extractable Fe concentrations were consistent with the results obtained by 57Fe Mössbauer spectroscopy and UV-vis spectra.