Fe Samples Research Articles

Electronic structures of MgO/Fe interfaces with perpendicular magnetization revealed by hard X-ray photoemission with an applied magnetic field

ABSTRACT We have developed hard X-ray photoelectron spectroscopy (HAXPES) under an applied magnetic field of 1 kOe to study the electronic and magnetic states related to the MgO/Fe interface-induced perpendicular magnetic anisotropy (PMA). In this work, we used MgO (2 nm)/Fe (1.5 and 20 nm)/MgO(001) structures to reveal the interface-induced electronic states of the Fe film. Perpendicular magnetization of the 1.5-nm-thick Fe film without extrinsic oxidation of the Fe film was detected by the Fe 2p core-level magnetic circular dichroism (MCD) in HAXPES under a magnetic field, and easy magnetization axis perpendicular to the film plane was confirmed by ex situ magnetic hysteresis measurements. The valence-band HAXPES spectrum of the 1.5-nm-thick Fe film revealed that the Fe 3d electronic states were strongly modified from the thick Fe film and a reference bulk Fe sample due to the lifting of degeneracy in the Fe 3d states near the MgO/Fe interface. We found that the tetragonal distortion of the Fe film by the MgO substrate also contributes to the lifting of degeneracy in the Fe 3d states and PMA, as well as the Fe 3d-O 2p hybridization at the MgO/Fe interface, by comparing the valence-band spectrum with density functional theory calculations for MgO/Fe multilayer structures. Thus, we can conclude that the Fe 3d-O 2p hybridization and tetragonal distortion of the Fe film play important roles in PMA at the MgO/Fe interface. HAXPES with in situ magnetization thus represents a powerful new method for studying spintronic structures.

Unraveling the effects Mn-site doping on structural, magnetic and magnetotransport properties of Nd0.67Sr0.33Mn0.9T0.1O3 (T= Mn, Fe, Cr, Ni)

The present work reports the effects Mn site doping on the structural, magnetic and magnetotransport properties of Nd0.67Sr0.33Mn0.9T0.1O3, where T = Mn, Fe, Cr and Ni. Structural analysis based on Rietveld refinement confirms that the samples crystallize in orthorhombic structure with Pbnm space group. A detailed investigation on the FTIR spectra hints to the improved metallic character of Nd0.67Sr0.33Mn0.9Mn0.1O3 and Nd0.67Sr0.33Mn0.9Ni0.1O3 samples. Strong ferromagnetic character of Nd0.67Sr0.33Mn0.9Mn0.1O3 and Nd0.67Sr0.33Mn0.9Cr0.1O3 is revealed from ZFC-FC magnetization studies, while the Fe and Ni doped samples possess strong AFM ground state. An irreversible metamagnetic transition is discernible from the hysteresis curve of Nd0.67Sr0.33Mn0.9Fe0.1O3. Transport studies reveal a charge ordered state in Fe doped sample close to its spin glass transition temperature, Tg = 65 K. Nd0.67Sr0.33Mn0.9Mn0.1O3 behave like a typical double exchange material with nearly same TC and TP values, whereas for all other samples TP lie much below TC. Low resistive state materialized in a strong AFM material as observed in Nd0.67Sr0.33Mn0.9Ni0.1O3, is rarely observed in manganites. Colossal MR values exhibited by Fe and Ni doped samples are understood based on phase separation scenario of manganites. Large dissimilarities evident in the magnetic and electronic properties of the compounds, though the dopant ions possess nearly same ionic size, are attributed to differences in their electronic configuration. Resistivity behavior of samples in different temperature regimes are comprehended based on existing models of conduction.

Ternary core-shell PdM@Pt (M = Mn and Fe) nanoparticle electrocatalysts with enhanced ORR catalytic properties.

In this work, we introduce composition-tunable core-shell-like PdM@Pt (M = Mn and Fe) nanoparticles (NPs) on carbon support (PdM@Pt/C) synthesized by one-pot sonochemical reactions using high-intensity ultrasonic probe (150 W, 20 kHz, with 13 mm solid probe) and investigate their electrocatalytic performance for oxygen reduction reaction (ORR). The core-shell-like structure of the NPs are evidenced by the elemental distribution maps obtained by energy dispersive X-ray spectroscopy equipped on scanning transmission electron microscopy. Based on the characterization data, PdM@Pt NPs were synthesized with variable elemental compositions (Pd49Fe21@Pt30, Pd17Fe31@Pt52, Pd46Mn6@Pt48 and Pd15Mn5@Pt80). All PdM@Pt samples are composed of large (~10 nm) and small (~3 nm) NPs, the large ones appear to be aggregates of the smaller ones, and the proportion of the larger NPs increases with the Pd content, which can be explained with the known mechanisms of sonochemical reactions of related systems. Electrochemical analyses on samples show that the ORR mass activity of PdM@Pt/C is 3-fold (normalized by Pt) and 1.7-fold (normalized by platinum group metal (PGM)) higher than those of Pt/C (commercial). All PdM@Pt/C sample show superior durability with the electrochemical surface area (ECSA) change of -4.4-+12.0% and half-wave potential change (ΔE1/2) of 8-14 mV after 10 k cycles accelerated stress test (AST) to Pt/C with ECSA change of -25.6% and ΔE1/2 of 19 mV.

Heavy Metals Contents in Some Commercially available Coffee, Tea, and Cocoa Samples in Misurata City – Libya

The purpose of the present study was to evaluate the concentrations of Mn, Cr, Fe, Cu, Zn, Pb, and Cd in 18 types of commercially available coffee, tea, and cocoa on Misurata city markets. The samples were dry digested and then measured by Microwave Plasma-Atomic Emission Spectrometry (MP-AES). The heavy elements levels were differed among the various types of analyzed samples. The concentrations of Mn were relatively higher than the other analyzed elements and varied between 1.0 – 673.3 mg/kg. The observed concentration ranges of the other elements, were as follows: Cr (0.1- 131.0 mg/kg), Fe (0.3 – 40.6 mg/kg), Cu (0.3 – 13.6 mg/kg), Zn (1.0 -20.9 mg/kg), Pb (1.8 – 4.4 mg/kg) and most Cd samples were below the instrument detection limits. The values determined for Mn, Cr, Fe, Cu, and Zn were lower than the maximum permissible limits. However, the concentrations of Pb were high according to the Brazilian law and Mercosul regulations, and the regulations of the European Union. Monitoring of heavy metal in food, like coffee, teas, and cocoa, provides useful information on safety features of food in regulatory procedures in terms of suitability of food for consumption, as well as its nutritional value.

Mineral Composition Evaluation in Energy Drinks Using ICP OES and Chemometric Tools.

This study reports the simultaneous determination of the total concentrations of Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, and Zn in17 samples of commercial energy drinks through inductively coupled plasma optical emission spectrometry and multivariate methods, such as Pearson correlation and principal component analysis (PCA), in order to conduct a more thorough evaluation of the original data. The samples studied were stored in two types of containers (polyethylene terephthalate bottles and aluminum cans) and purchased in the city of Belém (State of Pará, Brazil). The results showed high Na content in energy drinks, followed by K, Ca, and Mg. The accuracy of the optimized method was evaluated with the certified reference materials to assess trace elements in water (NIST 1643e); the resultant recoveries varied from 83 to 105%. Energy drinks stored in cans presented higher levels of aluminum and magnesium, while those bottled in polyethylene terephthalate bottles had a higher K content. There were significant differences between the observed Na concentrations and the values dictated on the drink package. Furthermore, PCA explained 70.38% of the total variance, allowing for an evaluation of the degree of similarity between the energy drinks studied and showing that the main contributions to the formation of groups are related to Fe, Na, Mg, and Zn contents. These results will be used to better understand the distribution of inorganic elements contained in energy drinks.

Comparative study of CO oxidation on biogenic lepidocrocite layered on anodic alumina samples

Leptothrix genus bacteria were cultivated in Lieske medium in presence of anodic Al2O3/Al to synthesize γ-FeOOH as a biogenic precursor for catalyst preparation. Different amounts of biogenic iron (0.6, 0.9, 9.2% Fe) were deposited. γ-FeOOH deposition on the support was identified the process being determined by the anodic Al2O3 surface structure. The catalytic activity in the CO oxidation reaction was examined by in situ diffuse-reflectance infrared spectroscopy up to 250 °C. A maximum conversion of 42% was achieved with 9.2% Fe sample. However, the lowest amount of reaction product CO2 was determined. Lepidocrocite conversion into maghemite occurred during catalytic experiments. Static adsorption study showed presence of carbonate (bidentate, monodentate) species and formates on the samples surface indicating that oxidation occurred at room temperature by CO interaction with (sub)surface oxygen. Bidentate carbonate species were not registered with 9.2% Fe sample. Additionally, inhibited formate species formation was registered on the same sample. In this case the biogenic iron coverage could be considered thicker and denser determining CO2 adsorption–desorption to/from the surface of iron-containing compound and anodic alumina. So, the higher CO conversion with 9.2% Fe sample was at the expense not only for transformation to CO2 but some part remained on the surface as strongly adsorbed species.

Cathode Properties of Na3FePO4CO3 Prepared By Mechanical Milling Method for Na-Ion Battery

Introduction In rechargeable batteries for grid storage, the cost performance is more important than the energy density. For large-scale batteries, the minor metal-free cathode active materials are attractive for Na-ion batteries because of their natural abundance and low cost. In addition, polyanionic cathodes are also attractive for the high thermal and chemical stability. Among the iron-based phosphate family, the theoretical capacity of Olivine-type LiFePO4 is restricted to 170 mAh/g and the Na counterpart, Maricite-type NaFePO4 is electrochemically inactive. On the other hand, a new polyanionic intercalation cathode Na3FePO4CO3 has high theoretical capacity of 190 mAh/g based on Fe2+/Fe4+ redox 1). Nevertheless, Na2.24FePO4CO3 synthesized by hydrothermal method can just deliver discharge capacity of 112 mAh/g at 10 mA/g, corresponding to 1.18 e- reaction, because of the oxidation of Fe2+ during hydrothermal process and intrinsic property of a poor ionic conductivity2). In order to improve electrochemical performance of Na3FePO4CO3, mechanochemical synthesis method by ball milling was tried in a manner similar to NaMF3 3). In addition, we investigated the cathode properties of Na3FePO4CO3 against Na metal anode and confirmed the reversible multi electron reaction in it. Experimental NaFePO4 + Na2CO3 /C composite was prepared by three-step mechanical ball milling. First, the mixture of Na2CO3 and maricite-NaFePO4 obtained by solid state method 4) with the molar ratio of Na2CO3 : NaFePO4 = 1 : 1 was put in the Ar-filled container with 3f-ZrO2 balls. This mixture was ball-milled using a planetary mill (Pulverisette7, Fritsch Japan Co., Ltd.) with a rotation speed of 600 rpm for 12 h. Second, the obtained mixture was ball-milled with 15 wt% acetylene black (AB, Denka Co., Ltd.) at a rotation speed of 500 rpm in Ar. And then, the above mixture was ball-milled again with 15 wt% AB with a rotation speed of 400 rpm in Ar. The cathode pellets were fabricated by mixing of the NaFePO4 + Na2CO3 /C composite powder with a 10 wt% polytetrafluoroethylene (PTFE) Teflon binder (Polyflon PTFE F-104, Daikin Industries, Ltd.) and punched into disks (ca. 30 mg weight and 10 mm diameter). The electrochemical performance of the NaFePO4 + Na2CO3 /C composite was evaluated by a 2032 coin-type cell with a nonaqueous electrolyte (1 M NaPF6/EC:DMC(1:1 in vol.) Tomiyama Pure Chemical Industries, Ltd.) and a glass filter separator (GA-55, ADVANTEC) against Na metal (Sigma-Aldrich). All cells were assembled in an Ar-filled glove box. The charge-discharge measurements were performed in galvanostatic mode at 25°C. Results and discussion The initial and second charge-discharge profiles of the mechanical milling-synthesized NaFePO4 + Na2CO3 /C composite cathode was obtained between 1.5 and 4.5 V at a rate of 0.4 mA/cm2 at room temperature (Fig. 1). During the first cycle, the obtained sample deliver a discharge capacity of 125 mAh/g, and even after 30 cycles, a reversible discharge capacity of 113 mAh/g, corresponding to 1.19 e- reaction per mole. In order to investigate the valence state of Fe in initial sample, Mössbauer spectroscopy experiment performed on initial sample. The result suggests that the 34% Fe in the sample is oxidized from 2+ to 3+. In Fig. 1, two plateaus of 2.6 and 4.2 V in the 2nd charged profile were observed, which correspond to the redox voltage of Fe2+/Fe3+ and Fe3+/Fe4+ in the reported value3). We will report about the electrochemical performance of NaFePO4 + Na2CO3 /C composite at RT and elevated temperature. The charge-discharge mechanism of NaFePO4 + Na2CO3 /C composite cathode will be also discussed at the presentation. References 1) H. Chen, et al., J. Am. Chem. Soc., 134, 19619 (2012). 2) A. Kitajou, et al., Electrochim. Acta., 245, 424 (2017). 3) W. F. Huang, et al., Sci. Rep., 4, 4188 (2014). 4) M. Avdeev, et al., Inorg.Chem., 52, 8685 (2013) Figure 1

Electrical, photoluminescence and ferromagnetic characterization of pure and doped ZnO nanostructures

The structural, electrical, optical, and magnetic properties of Zn0.95M0.05O samples (M = Zn, Ni, Cu, Fe, and Mn) are investigated. X-ray diffraction pattern revealed pure hexagonal wurtzite structure for all samples with an (210) additional peak formed only at 2 ~ 43.5° for Ni sample. The average crystalline diameter decreased from 20 nm for ZnO to 11.35 nm by the dopants, while the lattice and U parameters are nearly unchanged. Furthermore, the nonlinear coefficient and breakdown field are increased from 370.37 and 21.91 for ZnO up to 2291.67 and 55.96 by the dopants. The electrical conductivity of the upturn region is also increased by the dopants as compared to ZnO. There are two different values of the energy bandgap for each sample. The first gap is called fundamental gap Egh and its value above 3 eV, while the second gap is called optical gap EgL and its value below 2.6 eV. On the other hand, the UV band edges of photoluminescence intensity are 394, 402, 372, 390, and 404 nm, for Zn, Ni, Cu, Fe, and Mn samples. The Green shift is only recorded for Cu sample at 562 nm corresponding to 2.21 eV energy gap. The exciton energy, loss factor tan δ, and (N/m*) parameter are generally decreased by the dopants and follow the order Ni, Cu, Fe, Mn, and Zn, while lattice dielectric constant and inter-atomic distance are increased and follow the orders Zn, Mn, Fe, Cu, and Ni, and Zn, Ni, Cu, Mn, and Fe, respectively. Magnetization curves revealed clear room temperature ferromagnetism (RTFM) for Mn, Ni, and Fe samples, while they are showed weakly RTFM for Zn and Cu samples. Saturated magnetization Ms, remnant magnetization Mr, magnetization width, magnetic moment, coercivity of the field, and magneto-crystalline anisotropy factor are also affected by the dopants. Our results are discussed in terms of oxygen vacancies, valance state, and recombination of carriers, exhibited by the dopants to ZnO, rather than individual RTFM.

Studying the Thermal Neutron Spectrum of the W–Be Photoneutron Source at the Institute for Nuclear Research, Russian Academy of Sciences

The possibility is considered of reconstructing the thermal neutron flux density of a W–Be photoneutron source via neutron activation analysis of Ag, Mg, Fe, Mn, and Ti samples. The use of a simple function in the form AE−B describing the thermal region of the spectrum is discussed as an example of reconstruction. The dependence of the reaction rates’ deviation from the ones calculated on the parameters of the approximating function is investigated. The convergence of the reconstruction results as the number of experimental data grows is obtained. This means of recovery can be used for operational measurements of the thermal neutron flux density of the photoneutron source and to optimize the parameters of the source.

Application of intense ion beams to planetary physics research at the Facility for Antiprotons and Ion Research facility

This paper presents detailed 2D hydrodynamic simulations of implosion of a multi‐layered cylindrical target that is driven by an intense uranium beam. The target is comprised of a thick, high‐Z, high‐ρ cylindrical shell that encloses a sample material (Fe in the present case). Two options have been used for the focal spot geometry: an annular form and a circular form. The purpose of this work is to show that an intense heavy‐ion beam can induce the extreme physical conditions in the sample material similar to those that exist in the planetary cores. In this study, we use parameters of the beam that will be generated at the Facility for Antiprotons and Ion Research (FAIR), Darmstadt, in a few years' time. Production of these high‐energy‐density (HED) samples will allow us to study planetary physics in the laboratory. It is to be noted that planetary physics research is an important part of the FAIR HED physics program. A dedicated experiment named LAboratory PLAnetary Sciences (LAPLAS) has been proposed for this purpose. These simulations show that in such experiments an Fe sample can be imploded to the Earth's core conditions and to those in more massive rocky planets called Super‐Earths. Similarly, implosion of hydrogen and water samples will generate the core conditions of solar and extrasolar hydrogen‐rich gas giants and water‐rich icy planets, respectively. The LAPLAS experiments will thus provide very valuable information on the equation of state and transport properties of matter under extreme physical conditions, which will help scientists understand the structure and evolution of the planets in our solar system as well as of the extrasolar planets.

High-pressure neutron diffraction techniques based on Paris-Edingburgh press

Since the 1990s, with the benefit of available large-volumed samples, wide detector windows, and portability, Paris-Edinburgh press has been widely used in neutron facilities to study the structures and physical properties of condensed matter under high-pressure extreme conditions. In the present study, We perform high-pressure neutron diffraction experiments in neutron source of China using the Paris-Edinburgh press. The experiments are carried out on a high-pressure neutron diffraction spectrometer (Fenghuang) at China Mianyang Research Reactor (CMRR). Fenghuang is a high-intensity and moderate-resolution diffractometer which has been upgraded from a neutron powder diffractometer and can be used under ambient and extreme conditions. A single cylinder pump with a max load of 200 MPa provides a loading pressure for Paris-Edinburgh press, and a precise mobile platform is used to hang and to locate the Paris-Edinburgh press. Using the tungsten-carbide (WC) toroidal anvils with TiZr gasket, we obtain the neutron diffraction spectra of Fe samples at different pressures successfully. We also obtain the neutron diffraction spectra respectively at pressures of 9.7 GPa and 10.7 GPa by using a WC single-toroidal anvil and a WC double-toroidal anvil under load 100 MPa. The TiZr gasket blows out before the load reaches 100 MPa in the WC single-toroidal anvil assembly, while it remains good in the WC double-toroidal anvil assembly under the same load. The WC single-toroidal anvil assembly becomes unstable under load about 80 MPa, and the WC double-toroidal anvil assembly is still stable under load 100 MPa. Thus, the stability of the double-toroidal anvil assembly is much higher than that of the single-toroidal anvil assembly. It is found that the thickness of the gasket edge is very important for the stability of the assembly during loading. The thicker the edge of the gasket, the more stable the assembly is. The main reason is that the groove of the double concave anvil can enhance the lateral support ability of the gasket, thereby making the double concave surface assembly more stable than the single concave surface assembly.

Structural and magnetic characterizations of Co2MnO4 doped with Cr, Mn, Fe and Cu

The structural and magnetic properties of Co2-xMxMnO4 (M= Cr, Mn, Fe and Cu) samples are investigated. Element substitution does not change the cubic lattice structure within a range of concentrations. There is a structural transition from cubic to tetragonal with the excessive addition of Mn atoms. The site preference of transition metal atoms influences the interatomic interactions in the oxide system. The interatomic interactions of Co2MnO4 and CoMn2O4 samples are analyzed though ZFC/FC curves, the transition temperatures of which are attributed to the combined effect of magnetic interactions in different sublattices. The magnetic structure is restructured by atomic substitution and site preference, resulting in the compositional dependence of magnetic properties.

Plastic yielding and tensile strength of near-micrometer grain size pure iron

In order to investigate the influence on mechanical properties of grain size in the near-micrometer regime, samples of Fe with nearly full density were prepared using the spark plasma sintering (SPS) technique with average grain sizes of 1.0 µm, 2.6 µm and 4.0 µm. In each of these samples the resulting sintered material was in a nearly fully-recrystallized condition with a random texture. The mechanical properties of the samples were examined via tensile testing. A strong dependence of the tensile flow characteristics on the average grain size was observed in this size regime, with the 1.0 µm grain-size sample showing a very high strength, but no uniform elongation and a large yield drop developed in the 2.6 µm grain-size sample. Analysis of the grain size dependence of yield strength suggests a positive Hall-Petch deviation from the expected grain boundary strengthening in the SPS Fe samples, assuming a typical range of values for the grain boundary strength (Hall-Petch coefficient). Pre-compression of the 2.6 µm grain-size prior to tensile testing sample results in a removal of the yield drop and a corresponding large decrease in the yield stress by as much as 145 MPa. The observations suggest that the positive Hall-Petch deviation seen previously in the near-micrometer regime for fully recrystallized Al and Cu may also be present in Fe, and highlight the likely importance of dislocation source hardening in this grain size regime.

Elemental composition of surface soils in Nature Park Shumen Plateau and Shumen City, Bulgaria

Abstract Anthropogenic activities cause environmental pollution and alter biogeochemical cycles. Soils in cities and their vicinity are exposed to different pollutants. Nature Park Shumen Plateau is a protected area situated in the proximity of Shumen (Bulgaria). The aim of this research was to compare elemental composition of surface soil samples from Nature Park with two areas in Shumen city. Soil samples from seven sites on the territory of Nature Park and from two urban sites were collected. The elemental composition of the samples was determined using Energy Dispersive X-Ray Fluorescence technique. Principal component analysis and cluster analysis were performed to interpret the complex data. The content of 24 elements was determined: Br, Y, Zr, Mo, Ag, Cd, Sn, Sb, I, Cs, Ba, La, Ce Si, K, Ca, Ti, Mn, Fe, Cu, Zn, Rb, Sr, and Pb. Results presented here and previously showed that concentrations of heavy metals Cu, Zn, Cd and Pb are below the upper limit according to Bulgarian legislation. Concentrations of Mn and Fe in samples from Nature Park were comparable to the literature data reported for unpolluted areas. Principal component analysis and cluster analysis show similarity of the content of 24 elements between samples from Nature Park and from Shumen city. These findings are in accordance with our previous positive results from Allium-test: cytogenetic endpoints showed a presence of harmful compounds in Nature Park soils. The content of heavy metals in the surface soils studied show a lack of environmental risk for Nature Park. However, a similar distribution pattern of the investigated elements in the park and two anthropologically influenced areas in Shumen city indicated a potential hazard in Nature Park.

Multimetal organic frameworks as drug carriers: aceclofenac as a drug candidate.

BackgroundMultimetal organic frameworks (M-MOFs) were synthesized by including a second metal ion with the main base metal in the synthesis process to enhance their applications for drug delivery. Aceclofenac (ACF), a nonsteroidal anti-inflammatory analgesic drug of low aqueous solubility, was selected as a candidate for the drug delivery systemPurposeThis study aimed to evaluate the loading capacity (LC) and entrapment efficiency (EE) percentages of multi-Material of Institute Lavoisier (MIL)-100(Fe) (M-MIL-100(Fe)) for ACF.Materials and methodsHydrothermal synthesis procedure was used to prepare multi-MIL-100(Fe) samples (Zn I-MIL-100(Fe), Zn II-MIL-100(Fe), Ca I-MIL-100(Fe), Ca II-MIL-100-(Fe), Mg I-MIL-100(Fe), Mg II-MIL-100(Fe), Mn I-MIL-100(Fe), and Mn II-MIL-100(Fe)). The characterization of M-MIL-100(Fe) samples was evaluated by X-ray powder diffraction (XRD), Fourier transform infrared spectra, scanning electron microscope (SEM), TGA, and N2 adsorption isotherms. The LC of M-MIL-100(Fe) and EE of ACF were determined. Nuclear magnetic resonance (NMR) and zeta-potential analyses were employed to confirm qualitatively the drug loading within M-MIL-100(Fe).ResultsThe ACF LC of MIL-100(Fe) was 27%, whereas the LC of M-MIL-100(Fe) was significantly increased and ranged from 37% in Ca I-MIL-100(Fe) to about 57% and 59% in Mn II-MIL-100(Fe) and Zn II-MIL-100(Fe), respectively. The ACF@M-MOFs release profiles showed slow release rates in phosphate buffer solutions at pH 6.8 and 7.4 as compared to the ACF@MIL-100(Fe).ConclusionTherefore, M-MOFs showed a significant potential as a carrier for drug delivery systems.

Conduction-Electron Spin Resonance in HgSe Crystals

Samples of a gapless HgSe semiconductor with different iron impurity concentrations are investigated. HgSe:Fe samples are examined by the electron-spin-resonance technique. Multiple resonance lines caused by unpaired spins of different origins are analyzed. The properties of electrons localized at shallow impurities are described using a hydrogen-like model. The effect of an internal field on the resonance lines is established. It is found that the conduction of HgSe is not only nonparabolic, but also nonspherical.

The Potential of Plant-Based Compounds As Iron Chelators

Introduction: The use of iron-chelators is an important clinical treatment for iron overload diseases such as β-Thalassemia (Thal) and neurodegeneration with brain iron accumulation. Iron overload can impair immune cell, cardiac and neurological function. Iron chelation can alleviate some of this morbidity, but at increasing doses certain chelating agents can have serious side effects. Plant-based treatments may offer an alternative. In plants, Fe is required for photosynthesis and enzyme production but is often limited for uptake from the soil. When Fe is limited, plant roots may produce a range of compounds, including chelators, to assist in solubilizing Fe precipitates. Plant-produced phenolic acids such as p-coumaric acid (Cou), caffeic acid (Caf), or chlorogenic acid (CGA) have shown an affinity for Fe and may play a role in plant iron uptake. Plants adapted to environments where Fe is more difficult to access, such as alkaline soils, could show a higher prevalence of these compounds, along with plants generally abundant in phenolics. In this project, the alkaline tolerant plants Thuja plicata (cedar) and Lavandula x intermedia (lavender), along with the phenolic rich Populus trichocarpa x deltoides(Poplar), were investigated for their potential to produce Fe-chelators in response to low Fe.Methods: Cedar, lavender, and poplar cuttings were clonally propagated and cultivated aeroponically to improve efficiency of root collection. Extracts or exudates from roots grown with or without Fe were isolated for characterization as Fe-chelators. Phenolics from root washings were captured with chromatography and separated by collection into fractions in different solvents. These were evaluated for total phenolic concentration against gallic acid as a standard. An in vitro competition assay was used to characterize Fe-binding ability of root isolates. Isolates were compared to standard chelators DFO and EDTA, and model compounds Cou, Caf, and CGA to determine inhibition of the competition reaction. A bioassay quantified intracellular Fe in monocytic THP-1 cells (to model RE system) grown for 8 weeks with chronic relevant non-transferrin bound iron levels (4-20 μM Fe-citrate, CrFe) and without (Con). Cultures were also investigated for other effects of acute Fe treatment and potential chelators over time.Results: Aeroponic plant cultivation improved root health and growth compared to previous hydroponic methods. Fe-deficient plants produced isolates that were different from Fe-normal plants following an analysis of phenolic fractions. Isolates in isopropanol were found to be 104% more plentiful in Fe-deficient poplars, which may indicate Fe-chelating potential. Between species, lavender had the highest phenolic concentration in root isolates, followed by cedar and poplar. Cedar roots showed an increased composition of phenolics compared to Fe-deficient poplar, supporting the potential for species-specific Fe responses. Analysis of Fe responses between species is ongoing. Competition assays showed that lavender root isolates exhibited 36% greater inhibition than 80 μM EDTA and 46% greater than 100 μM DFO. In direct comparison to DFO at 50 μM, Caf was equivalent, CGA had 30% greater inhibition, and inhibition by Cou was 41% lower. CrFe cells had 104% greater intracellular Fe compared to Con cells. Addition of acute Fe over 24 h significantly increased Fe content of cells grown in both CrFe and Con conditions and altered cell viability. A dose-dependent reduction in Fe levels was seen with increasing CGA in both CrFe and Con cells. Overall, Fe in samples treated with CGA were comparable to those with DFO. The effect of plant root isolates on intracellular Fe and cell viability is ongoing.Conclusion: Plant species from different soil types have altered responses to Fe-deficiency. Lavender and cedar, more tolerant of unfavorable soils, may produce more Fe-chelating phenolics as part of their response to low Fe. This was observed in vitro, as lavender isolates contain chelators that stimulate inhibition of the competition reaction similarly to DFO and EDTA at moderate concentrations. As a model, Caf, CGA and Cou also prove to have Fe-chelating activity comparable to DFO at lower concentrations. After using these plant compounds in bioassays, their successful reduction of intracellular Fe in CrFe THP-1 cells show the promise of plant root isolates to be clinically useful Fe-chelators. DisclosuresNo relevant conflicts of interest to declare.

Aerobic Oxidation of Benzylic Hydrocarbons by Iron‐Based Metal Organic Framework as Solid Heterogeneous Catalyst

AbstractIn the present work, the aerobic oxidation of indan is reported using Fe(BTC) (BTC: 1,3,5‐benzenetricarboxylate) as solid heterogeneous catalyst and tetrabutylammonium bromide (TBAB) as an additive under mild reaction conditions. Although aerobic oxidation of indane has been reported earlier using MOFs as heterogeneous catalysts, these methods require higher reaction temperature and catalytic amounts of radical initiator. Therefore, this study aims to report the aerobic oxidation of indan employing Fe(BTC) as catalyst without the need of initiators under mild reaction temperature. The catalytic data reveal that the indan conversion reaches to 18% with 97% selectivity of indanol at 80 °C in acetonitrile as solvent. Furthermore, the catalyst stability is surveyed by performing reusability experiments and observing no decay in its activity. On other hand, comparison of fresh with three times reused Fe(BTC) samples by powder X‐ray diffraction (XRD) and scanning electron microscope (SEM) indicates that the crystallinity and morphology of the reused sample, respectively is retained during the course of the reaction. Finally, two times reused Fe(BTC) exhibits similar electron spin resonance (ESR) pattern with that of fresh Fe(BTC), suggesting no changes in the oxidation state of iron.

Characterization of nano-crystalline Samaria-Fe and Yttria-Fe co-doped ceria solid solutions prepared by hydrothermal technique

Powders of Samaria, Yttria doped ceria and co-doped with iron were synthesized by hydrothermal method. The iron content for all the investigated compositions is 0.5 wt. %. The powders were investigated by thermogravimetric analysis (TGA) X-ray diffraction (XRD), Infrared (IR), Transmission electron microscope (TEM) and Raman specra. The effect of autoclaving time on the crystallinity was studied. The powders were impacted and sintered at different temperatures. The density and linear shrinkage were investigated for all sintered bodies. XRD revealed that the powders crystallize in fluorite centered cubic structure with the improvement in crystallinity. The presence iron in the solid solution lowered the degree of crystallinity. TEM images for the co-doped powders displayed semi-rounded nano-sized particles with narrow size distribution. It is concluded that the optimum fluorite structure for solid solutions is obtained with 10 mol % Samaria doped ceria (10SDC)Fe and iron codoped 10 mol % Yttria doped ceria (10YDC) Fe samples.

The Formation and Evolution of Defects in Nanocrystalline Fe During Indentation: The Role of Twins in Pop‐Ins

Nanoindentation is a most common experimental tool used for obtaining information on the mechanical behavior of materials. This is done by qualitatively relating the occurrence of pop‐ins (in the load–displacement plots) to microstructural changes such as dislocation formation, fracture of surface oxides, or slip transmission. The present study takes a first approach in directly verifying the micro‐plasticity processes that give rise to such pop‐ins by performing molecular dynamics indentation simulations in BCC Fe‐nanocrystals with a Σ5 symmetric tilt boundary. The simulations allow to track the material behavior throughout the indentation process, and illustrate that each pop‐in is related to twin formation, twin growth, de‐twinning, dislocation nucleation and glide, or dislocation–grain boundary interactions. For the particular Σ5 boundary considered, it is found that the pop‐ins are most closely associated with twin formation. Although pop‐ins have been related to dislocation nucleation, a direct correlation between twinning and pop‐ins has not been shown before. Adding C segregants to the Fe sample, reduced the formation of twins after initial yielding, and allowed for dislocation activity to become the more dominant deformation mechanism.