Fe Peak Research Articles

Sample preparation of blood plasma enables baseline separation of iron metalloproteins by SEC-GFAAS

The analysis of human plasma for biomarkers holds promise to revolutionize disease diagnosis, but is hampered by the inherent complexity of the plasma proteome. One way to overcome this problem is to analyze plasma for a sub-proteome, such as the metalloproteome. Previous studies employing size-exclusion chromatography (SEC) coupled on-line to an inductively coupled plasma-atomic emission spectrometer (ICP-AES) have revealed that plasma contains ~12 copper, iron and zinc metalloproteins. This included the iron metalloproteins transferrin (Tf) and a recently identified haptoglobin-hemoglobin (Hp-Hb) complex, which is formed in plasma when red blood cells rupture. Since this SEC-ICP-AES method required a sample volume of 500 µL to generate diagnostically useful results, we sought to develop an alternative SEC-based hyphenated approach using a smaller SEC column (150 × 5 mm I.D.) and a graphite furnace atomic absorption spectrometer (GFAAS) as the iron-specific detector. A designed interface enabled the integration of the SEC system with the GFAAS. Baseline separation between the Hp-Hb complex and Tf was achieved by developing a sample preparation procedure which involved the chelating agent-based mobilization of Fe from Tf to a small molecular weight Fe complex. Spiking of human plasma (1.0 mL) with red blood cell lysate (1–2 µL) increased only the intensity of the Fe peak corresponding to the Hp-Hb complex, but not that of Tf. Since the developed SEC-GFAAS method requires only 50 µL of plasma for analysis, it can now be employed for the cost-effective quantification of the clinically relevant Hb-Hp complex in human plasma in <50 min.

Anisotropy of hydrogen plasma effects in bulk n-type β-Ga2O3

Bulk n-type β-Ga2O3 samples with orientation (−201) and (010) were exposed to a high density hydrogen plasma at 330 °C for 0.5 h. The effects were radically different for the two orientations. For the (−201) sample, H plasma exposure increased the net surface concentration of shallow donors from 2.7 × 1017 cm−3 to 2.6 × 1018 cm−3, with the shallow donors having an ionization energy close to 20 meV as deduced from the temperature dependence of the series resistance of Ni Schottky diodes. By sharp contrast, H plasma exposure of the (010) sample led to a strong decrease in the net shallow donor density from 3.2 × 1017 cm−3 to below 1015 cm−3 in the top 0.9 μm of the sample and to 3.2 × 1016 cm−3 near the edge of the space charge region at 0 V, with the total width of the region affected by plasma treatment being close to 1.1 μm. For both orientations, we observed a major decrease in the concentration of the dominant E2 traps near Ec-0.82 eV related to Fe acceptors. The deep trap spectra in hydrogenated samples were dominated by the E2* traps commonly ascribed to native defects in β-Ga2O3. The peak of these traps with a level near Ec-0.74 eV was masked in the starting samples by the peak of the E2 Fe acceptors present in high concentration, so that E2* only broadened the Fe peak on the low temperature side, but could be revealed by the modeling of the spectra. The concentration of the E2* center was not strongly affected in the hydrogen-treated samples with orientation (010), but in the (−201) samples, the concentration of the E2* peak was greatly enhanced. The results are discussed in conjunction with previous reports on hydrogen plasma treatment of β-Ga2O3 and on obtaining p-type conductivity in the surface layers of β-Ga2O3 crystals annealed in molecular hydrogen at high temperatures [Islam et al., Sci. Rep. 10, 6134 (2020)].

In Situ Raman Spectroscopic Analysis on Carbon Steel, Immersed in Aqueous Solutions at Different pH and Anions

In situ Raman spectroscopic studies on carbon steel specimens immersed in aqueous solutions showed the presence of Fe hydroxy salt, specifically green rust (GR), as the initial corrosion product in acidic, neutral and alkaline conditions. With increasing exposure time, GR was transformed to oxy-hydroxides, predominantly lepidocrocite (γ-FeOOH) in the upper layer and magnetite (Fe3O4) in the oxygen-deficient lower layer. The stability of GRs and their transformation are found to be dependent on the pH of solutions and anions present. The de-convoluted Fe peak in the Fe 2p3/2 region of XPS spectra of the corrosion products, formed on CS specimen immersed in tap water for 80 h, indicate the presence of lepidocrocite phase (γ-FeOOH), which was also evident from the laminar morphologies seen in SEM micrograph. The predominance of lepidocrocite over magnetite phase, in the presence of sulfate ions and in the low pH conditions, was in good agreement with the highest corrosion rate observed.

Improved electrocatalytic performance for nanosensor comprising alkaline treated MWCNTs for dopamine detection

The MWCNTs were purified by acid treatment using nitrating mixture. The Morphology and structure of perstine MWCNTs and purified MWCNTs were characterized by Scanning Electron Microscope and Transmission Electron Microscope. Energy Dispersive X-ray analysis of MWCNTs before and after acid treatment revealed that acid treatment could removal of encapsulated catalyst particles. XRD pattern of purified sample indicates that the Fe peaks have been decreased. This confirms that purification process is effectively reducing Fe component. The purified- MWCNTs is dispersed in alkali media and used for the preparation of modified carbon paste electrodes for the electrochemical detection of dopamine (DA). Electrochemical parameters, such as the surface area of the electrode, and the lower detection limit, were calculated and compared with those of the MCPE prepared from purified- MWCNTs treated with NaOH and KOH. KOH treated MCPE shows increase in surface area when compare to bare-CPE, P-MWCNT/NaOH-MCPE. The analytical performance is also evaluated for the detection of DA in dopamine hydrochloride injection sample at modified electrodes.

Distribution character of localized iron microniche in lake sediment microzone revealed by chemical image.

DGT (diffusive gradients in thin films) technique and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) for heterogeneous distribution of the soluble labile iron (Fe) at submillimeter resolution in lake sediment porewater are reported. The soluble labile Fe species include ion and labile organic complexes. The chemical images in two dimensions (2D) for DGT concentration of Fe (CDGT(Fe)) are investigated for Fe remobilization character. There are 902 CDGT(Fe) values between 1000 and 2000 μg L-1, 463 values between 2000 and 3000 μg L-1, and 112 values over 3000 μg L-1 in all chemical maps. Based on the linear correlation relationships between CDGT (Fe) and total Fe (TFe), total organic carbon (TOC), acid-volatile sulfide (AVS), Eh, concentrations of the soluble reactive phosphorus (P) (SRP), and soluble labile trace metals (Zn, Cu, Pb, and Zn) in a vertical 1D profile of sediment or porewater, Fe release mechanisms are mainly due to the reductive Fe release from iron oxyhydroxides and the decomposition of organic matter in algae biomass and deep sediment layer. It can be used to explain the formation mechanisms of Fe microniches in chemical maps with heterogeneous character to a great extent. CDGT(Fe) peak flux in the center of Fe microniche and the low CDGT (Fe) at the edge of a microniche are due to the formation of the insoluble iron sulfide and the abundant acid-volatile sulfide (AVS) in sediment. The verified co-remobilization of the soluble labile Fe and trace metals or SRP in sediment porewater can be used to predict their simultaneous release from Fe microniches with the large CDGT (Fe) peaks. The different kinds of Fe microniche zones and hot spots from sediment/water interface (SWI) to deep sediment correspond to the formation mechanisms of microniches mentioned above. Moreover, some narrow Fe microniche zones with the large CDGT (Fe) across chemical maps are due to the desorption of Fe(II) from the freshly formed oxide on Myriophyllum verticiilatur roots, which are located at sites of microniche zones.

Infrared Spectroscopy of Symbiotic Stars. XII. The Neutron Star SyXB System 4U 1700+24 = V934 Herculis

Abstract The X-ray symbiotic (SyXB) V934 Her = 4U 1700+24 is an M giant–neutron star (NS) binary system. Employing optical and infrared radial velocities spanning 29 yr combined with the extensive velocities in the literature, we compute the spectroscopic orbit of the M giant in that system. We determine an orbital period of 4391 days, or 12.0 yr, the longest for any SyXB and far longer than the 404 day orbit commonly cited for this system in the literature. In addition to the 12.0 yr orbital period, we find a shorter period of 420 days, similar to the one previously found. Instead of orbital motion, we attribute this much shorter period to long secondary pulsation of the M3 III SRb variable. Our new orbit supports earlier work that concluded that the orbit is seen nearly pole-on, which is why X-ray pulsations associated with the NS have not been detected. We estimate an orbital inclination of 11.°3 ± 0.°4. Arguments are made that this low inclination supports a pulsation origin for the 420 day secondary period. We also measure the CNO and Fe peak abundances of the M giant and find it to be slightly metal-poor compared to the Sun, with no trace of the NS-forming supernova event. The basic properties of the M giant and NS are derived. We discuss the possible evolutionary paths that this system has taken to get to its current state.

Iron record associated with sandstorms in a central Asian shallow ice core spanning 1956–2004

The metal elements in alpine ice can provide historical information about natural mineral dust and anthropogenic pollutant emissions. To determine how the Fe concentration and flux variations relate to natural sandstorms and anthropogenic emissions from 1956 to 2004 A.D., Fe, Al, Pb and other element records were measured in a shallow ice core from the Miaoergou Glacier in East Tienshan, central Asia. The results indicate that the dissolved Fe (DFe) and total dissolved Fe (TDFe) peaks are well correlated with sandstorms from the surrounding Taklamakan Desert since at least 1956 A.D. The concentrations and fluxes of Pb show continuously increasing trends since 1995 A.D. due to the accelerating progress of the industrial revolution in China during this period, while the DFe and TDFe concentrations and the fractional Fe solubility exhibit no significant variations during this period. These results provide an ideal opportunity to investigate the effects of the natural Fe record in an arid region.

Investigation of boron effect on the densification of Fe-50%Ni soft magnetic alloys produced by powder metallurgy route

Abstract The soft magnetic iron-nickel alloys with 50 wt % nickel were produced by powder metallurgy route. High purity and fine particle size iron and nickel powders were blended in Turbular mixer and compacted uniaxially with compaction pressure of 700 MPa. The Fe and Ni were mixed in ratio of 1:1 and then nano-size elemental boron (0 - 0.75 wt %) was added with the increment of 0.25%. The green samples were sintered at 1330 oC in Argon atmosphere with sintering time of 2 and 4 hrs. Sintering time and temperature effect on densification, mechanical properties and microstructure were investigated. Furthermore, effect of boron additive on microstructure, mechanical properties and densification were also studied. Samples with higher sintering time showed better density and hardness. In X-ray diffraction patterns of sintered samples, Fe and Ni peaks disappeared which indicates the complete alloy formation and only peaks of γ-FeNi phase detected. The addition of elemental nano-size boron has shown significant effect on densification and mechanical properties.

PENGARUH SUHU PADA EKSTRAK DAUN CINCAU HIJAU (CYCLEA BARBATA MIERS) SEBAGAI INHIBITOR KOROSI BAJA PEGAS DAUN

This study aims to determine the extract of green cincau leaves (Cyclea Barbata Miers) as a corrosion inhibitor soaked in 3% NaCl corrosive medium. To determine the effect of concentration and temperature to connect steel, the average inhibitor is 0, 2, 4, and 6% and each temperature is 40 and 80 . To find out the measurements done by the method, save weight. Corrosion rate at immersion temperature is 40 lower than speed at 80 immersion temperature. To find out the phase formed and the structure of the sample in XRD and SEM-EDS characterization. The X-Ray Diffraction (XRD) characterization results show that the phase formed is pure Fe. XRD results showed that the lowest Fe peaks were formed on samples without inhibitors at 80 .The results of SEM characterization of PGDaun-80-6 steel also showed that it looked more corroded, and the PGDaun-40-2 sample looked slightly corroded. This result is reinforced by the percentage of corrosion products shown in the EDS results

A Study on Corrosion Inhibitor for Mild Steel in Ethanol Fuel Blend.

The main aim of this study is to investigate Aganonerion polymorphum leaf-ethyl acetate extract (APL-EAE) and its inhibiting effect for steel in ethanol fuel blend. The immersion test, electrochemical and surface analysis techniques were successfully carried out in this research. Scanning electron microscope images indicated that the ethanol fuel blend induced pitting corrosion of steel. Remarkably, the surface of the sample containing 1000 ppm APL-EAE is smoother than the others submerged in different conditions. The electrochemical impedance spectroscopy result shows that APL-EAE has formed a good protective layer, preventing corrosive factors from hitting the steel surface. The potentiodynamic polarization data argue that the corrosion inhibition efficiency was strengthened with the increase of APL-EAE concentration. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated less intensity of Fe peaks, higher intensity of C1s peak and the appearance of organic peaks (N1s, P2p, O1s) from specimens with and without APL-EAE addition. Therefore, the results suggest the formation of the protective film on steel surface and affirm that APL-EAE has served as an effective corrosion inhibitor for steel in ethanol fuel blend.

Microstructure and palygorskite neoformation in pedogenic calcretes of central Morocco

The aim of this research was the micromorphological and mineralogical characterization of calcrete outcrops located in central Morocco, with particular focus on microstructure development and palygorskite formation processes. Two study sites in the Al Haouz Plain (ca 30km west to Marrakech city) were identified, in an area dominated by Quaternary sedimentary formations including layers cemented by carbonate and widespread calcareous crusts at the surface. The calcrete samples were examined by means of polarizing microscopy from thin sections, scanning electron microscopy / energy-dispersive X-ray spectroscopy (SEM/EDX) from undisturbed samples, and X-ray diffraction (XRD) methods. The matrix of the calcrete material cementing the schist fragments composed of abundant calcite was associated mainly with palygorskite, quartz, and to a lesser extent illite/mica, feldspar, and chlorite. SEM observations indicated that palygorskite mainly occurred as fibres, fibre bundles and networks mainly grown on and/or enclosing calcite rhombohedrons. The EDX spectra of the palygorskite fibres exhibited strong silicon (Si) peaks followed by Al, Mg and Fe peaks. The EDX analysis of calcite rhombohedric crystals exhibited a strong Ca peak, followed by weak peaks of Si, Mg, Al and Fe possibly due to nearby or overlapped palygorskite crystals. One main palygorskite neoformation process was described. Palygorskite was authigenically formed (neoformed) during and after precipitation of calcite from percolating soil solutions in a near-surface setting. Peculiar sub-rounded microstructural units, here designated as pedogenic ooids/pisoids (according to the size), were determined in the matrix of the studied calcretes, associated to pendants and clay-rich rims surrounding them.

Low Voltage Charge/Discharge Behavior of Manganese Hexacyanoferrate

Recently, Prussian blue analogues (PBAs) have been reported to exhibit a low voltage charge/discharge behavior with high capacity (300–545 mAh/g) in lithium-ion secondary batteries (LIBs) [...]

X-ray Photoelectron Spectroscopy (XPS) analysis of low oxidation pressure behavior of FeAl –alloys at 600°C and 700°C

The low oxidation pressure behavior of binary FeAl alloys has been examined at different temperatures of 600-700°C. Polycrystalline and single-crystalline samples of Fe-10Al and Fe-25Al were oxidized for 1 h at 10-6 mbar of oxygen in an ultra-high-vacuum chamber (UHV). Prior oxidation, samples were prepared by sputter-annealing cycles in UHV. After oxidation, the samples were analyzed by X-ray Photoelectron Spectroscopy (XPS). The formed oxide layers on the surfaces consist of FeAl2O4 and Al2O3 showing that Al has a dominating role during the oxidation process. From XPS peaks, the composition of the Fe peaks of the oxide layer consists of Fe metal, FeAl-alloys, and FeO. Meanwhile, the composition of the Al peak is changed from Al metal, FeAl-alloys and Al2O3 at 600°C to Al metal, FeAl-alloys and FeAl2O4 on 700°C. From XPS sputter depth profiles, it is shown that the oxide layer was growing with increasing temperature, and the single-crystalline Fe-10Al has a thicker formed oxide layer than poly-crystalline Fe-25Al with same oxidation treatment.

Double sporadic metal layers as observed by colocated Fe and Na lidars at Wuhan, China

AbstractIn this paper, we report a set of double sporadic layer events observed by Fe and Na lidars over Wuhan, China. The two sporadic metal layers above normal layer were named as upper and middle sporadic metal layers, respectively. In these events, the upper, middle, and normal Fe layers presented altitude separately. There were nine double sporadic Fe events observed in 163 nights during 2010–2013. Eight of the nine events were observed in summer. The maximum ratios of peak density for upper and middle sporadic Fe layers to normal Fe layer were up to ~375% and ~225%, respectively. The peak altitudes of upper (middle) sporadic Fe layers were in the range of 102–107 km (95–98.5 km). The double sporadic Fe layers lasted more than 2 h. Interestingly, we found that density enhancement occurred simultaneously in upper, middle, and normal Fe layers on two events. On the nine Fe events, there existed five nights of colocated Na lidar observations. We found that double sporadic Na and Fe layers simultaneously appeared. They presented similar structures, altitudes, and temporal variations in all five compared events. A little different from Fe, the middle sporadic Na layer was not separated from Na main layer maybe for the wide altitude range of Na main layer. The ratios of upper (middle) sporadic Fe and Na peak values were in the range of 6.6–52 (0.57–6.58). While the exact formation mechanism responsible for double sporadic metal layers is still unclear, some possible explanations and corresponding observations are discussed.

Trace metal diagenesis in sulfidic sediments: Insights from Chesapeake Bay

Sediments were recovered from the mid-bay portion of the Chesapeake Bay when bottom water conditions were sulfidic. Metal concentrations (Fe, Mn, Ba, V, Ni, Cu, Co, Cd, Mo, U, and Re) were determined in both pore waters and solid phase samples, which were determined using total and nitric acid digestion (EPA 3051a) methods. V, Cr, and Ni were preferentially retained in pore waters even under sulfidic conditions that would normally result in authigenic accumulation, likely due to complexation with dissolved organic matter (DOM). Mo was efficiently removed from pore waters in the zone in which FeS phases and polysufides are available. Re was not delivered to the sediments through the Mn/Fe shuttle, so that its diffusive flux into sediments solely depends on the extent of reducing conditions.A non-steady state oxygenation event was recorded in the solid phase, with coincident solid phase enrichments in Fe, Mn, Ni, Cu and Co. Deeper enrichments in U and Mo likely reflect remobilization from the relict Fe and Mn peaks, downward diffusion into more reducing conditions, and subsequent immobilization. The absence of peaks in solid phase Re, Cr and Cd was indicative of their lack of association with Mn and Fe oxides and/or resistance of their respective authigenic phases to oxidation on these seasonal to yearly timescales. Relative changes within the solid phase profiles were captured using the acid digestion method for Fe, Ni and Co, and acid digestion concentrations were within 90% of the total concentration for Mn and Cu. The presence of excess pore water sulfide may have promoted the removal of trace metals from the detrital fraction resulting in the formation of authigenic sulfides that might become mobile during oxygenation events.

GALAH Survey: Chemical tagging and disk reconstruction

AbstractThe GALAH survey is now in its second year of a five‐year campaign to observe roughly one million stars in the southern hemisphere down to a limiting magnitude of V = 14. The project exploits the HERMES 400‐fibre échelle spectrograph at the Anglo‐Australian Telescope to measure up to 30 elemental abundances and radial velocities (≈1 km s–1 accuracy) for each star at a resolution of R = 28000. These elements fall into 8 independent groups (e.g. α, Fe peak, s‐process). For all GALAH stars, Gaia will provide distances to 1 % and transverse velocities to 1 km s–1 or better, giving us a 14D set of parameters for each star, i.e. 6D phase space and 8D abundance space. A few percent of GALAH stars will also have Kepler K2 seismological data. Here we focus on the prospect of chemically tagging the old stellar disk and making a direct measurement of how stellar migration evolves with cosmic time.

Numerical Modeling of Reinforced Concrete Beams Strengthened by NSM-CFRP Technique

The NSM method has been used in recent years for the strengthening of RC beams with CFRP materials. A numerical study has been carried out on rectangular RC beams, strengthened with NSM-CFRP by using FE code ATENA. The numerical FE simulations were compared with experimental measurement tested by other investigators on specimen strengthened with NSM CFRP strips. On overall, the predicted FE peak loads and mid-span deflection responses agreed quite well with the corresponding measured experimental tested data at all stages of flexural loading. Therefore, the developed FE model is suitable as a practical and economical tool especially in parametric studies for accurate modeling and analysis of flexural strengthening of RC members with NSM-FRP reinforcement.

A new and direct method for the determination of trace elements in spinach using differential pulse polarography

For the trace determination of elements in spinach a new differential pulse polarographic (DPP) method is established. The polarograms were taken in various electrolytes and pH values in the presence of digested spinach sample. Trace element determinations were made in acetate and ammonia electrolytes at various pH values, with or without EDTA. Fe and Cu peaks could be separated and determined at pH7, acetic acid electrolyte in the presence of EDTA. Ni and Zn peaks could be separated and determined in ammonia buffer at pH10. Lead could be determined at pH2 acetic acid and Mo (VI) was determined at pH4 acetate buffer, EDTA medium. Selenite was determined from its hydrogen catalytic peak. The trace element in spinach was found as Fe 15μg/g, Cu 17μg/g, Ni 8μg/g, Zn 27μg/g, Pb 47μg/g, Mo 43μg/g, and Se 762μg/g.

Fabrication and characterization of nanoparticle MgO/B4C composite by mechanochemical method

In this study, nanoparticle boron carbide was produced after the reduction of boron oxide with magnesium under the presence of carbon by using mechanochemical synthesis method. During the synthesis processing, microstructure and phase transformations of powders were performed by using X-ray diffraction (XRD), Fourier-transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM). At the end of 2 h, reaction products (MgO, B4C) were determined by XRD and FT-IR examinations. Nanoparticle B4C single-phase crystalline structure from the MgO/B4C composite powder mixture, which was the reaction product, was obtained by leaching process. With the increase in the synthesis period, starting material peaks diminished and Fe peak intensity became evident. After the HRTEM examinations, it was determined that synthesized B4C particles were within range of 10–200 nm especially in the activation of leaching process. Additionally, by using spot pattern analysis method, planes represented by B4C particles were calculated.

PALLADIUM ISOTOPIC EVIDENCE FOR NUCLEOSYNTHETIC AND COSMOGENIC ISOTOPE ANOMALIES IN IVB IRON METEORITES

The origin of ubiquitous nucleosynthetic isotope anomalies in meteorites may represent spatial and/or temporal heterogeneity in the sources that supplied material to the nascent solar nebula, or enhancement by chemical processing. For elements beyond the Fe peak, deficits in s-process isotopes have been reported in some (e.g., Mo, Ru, W) but not all refractory elements studied (e.g., Os) that, among the iron meteorites, are most pronounced in IVB iron meteorites. Palladium is a non-refractory element in the same mass region as Mo and Ru. In this study, we report the first precise Pd isotopic abundances from IVB irons to test the mechanisms proposed for the origin of isotope anomalies. First, this study determined the existence of a cosmogenic neutron dosimeter from the reaction 103Rh(n, beta-)104Pd in the form of excess 104Pd, correlated with excess 192Pt, in IVB irons. Second, all IVB irons show a deficit of the s-process only isotope 104Pd (\varepsilon 104Pd = -0.48 ± 0.24), an excess of the r-only isotope 110Pd (\varepsilon 110Pd = +0.46 ± 0.12), and no resolvable anomaly in the p-process 102Pd (\varepsilon 102Pd = +1 ± 1). The magnitude of the Pd isotope anomaly is about half that predicted from a uniform depletion of the s-process yields from the correlated isotope anomalies of refractory Mo and Ru. The discrepancy is best understood as the result of nebular processing of the less refractory Pd, implying that all the observed nucleosynthetic anomalies in meteorites are likely to be isotopic relicts. The Mo-Ru-Pd isotope systematics do not support enhanced rates of the 22Ne(alpha,n)25Mg neutron source for the solar system s-process.