Equivalent Amount Of Iron Research Articles

Transferability between soil organic matter measurement methods for database harmonization

Soil organic matter (SOM) is one of the most important soil-forming factors and complex with a chemical composition not fully known. The amount of SOM traditionally is estimated by stoichiometric determination of carbon dioxide (CO2) released from oxidation reaction with a chromium mixture, hence the term soil organic carbon (SOC). The two most common oxidation methods are Tyurin (T) and Walkley-Black (WB). However, the efficiency of organic carbon oxidation depends upon the conditions of the oxidation reduction (redox) reaction (temperature, reagent concentration, oxidation time), which vary for both methods. The lack of consistent results from the oxidation methods has led to widely different conversion factors. Although the Tyurin’s method has been slowly removed from some laboratories, there still remains a large number of samples, especially from Eurasia, that have been measured by this method for more than a century and continue at the present time. The objective of this research was to develop equations or pedotransfer functions (ptf) for converting SOC determined by the Tyurin method to current and more widely used methods, such as WB and dry combustion (DC).A comparative analysis was performed for the assessment of soil organic carbon content obtained by Tyurin and Walkley-Black methods for ten quality control soil samples and 100 field soil samples. The selected soils differed in their genesis, geographical origin, and organic carbon content. SOC determined by dry combustion, providing a maximum oxidation of organic carbon, was used as a standard for comparing Tyurin and WB methods. The conversion factors from Corg by DC developed from equations (ptf) were 1.15 and 1.30 for WB and Tyurin methods. The SOM measurement error for both methods did not exceed 20%. The relationship between the absorption of calibration solutions and the mass of sucrose carbon or the equivalent amount of iron (II) for the entire OC range in this study was very strong (r = 0.99). The values of the calibration function coefficients (A0, K) of the calibration functions A = A0 + Km (OC) for both methods, did not depend upon the nature of the reducing agent. The relative error of the K coefficients when using two reducing agents (Mohr’s salt or sucrose) was not more than δ2 ≤ 2.5%. Soil samples prepared using the Tyurin method experienced additional dispersion compared to the Walkley-Black method, which caused higher values in the measurement of SOC even after centrifugation of soil suspensions. The mean SOC measured value by the Tyurin method combined with 48 h settling time was comparable with the mean SOC measured by dry combustion.The established coefficients ensure that the results are transferable and consistent with the standard method. The results from this study facilitate the integration of the accumulated data that are analyzed by different methods across the Eurasian countries into one comprehensive database that could be incorporated into the global network for monitoring soil quality and carbon stocks

Fractional Absorption of Iron from Crickets Consumed with Refined or Whole Meal Maize Porridge in Young Adult Women (OR07-06-19)

ObjectivesEdible insects are considered as an alternative source of proteins, but in addition are also rich sources of minerals. However, no studies have investigated the bioavailability of minerals from edible insects in humans. House cricket (Acheta domesticus) is an edible insect species that is commonly consumed in low and middle income countries where the prevalence of iron deficiency and anaemia is relatively high. We aimed to assess the fractional iron absorption of iron from house crickets in humans after addition to either a refined (low-phytate) or a whole meal (high-phytate) maize porridge meal. A second objective was to assess the fractional iron absorption from maize porridge meals when crickets were added. MethodsA single blind randomized cross-over trial was conducted. We recruited 24 females (18–30 years) with serum ferritin < 25 ng/mL and body weight < 65 kg. Six different meals with equivalent amounts of iron were randomly administered to each participant in two series, consisting of either refined (low-phytate) or whole meal (high-phytate) maize porridge with A) intrinsically 57Fe labelled house crickets; B) 58FeSO4; and C) unlabelled house crickets and 54FeSO4. Fractional iron absorption was determined by measuring shifts in Fe isotope ratios incorporated into erythrocytes that were collected before and 14 days after administration of each series of experimental meals. ResultsFor refined maize porridge, mean fractional absorption of iron from meal B was higher (13.55%; P < 0.001) than from meals A (1.99%) and C (3.12%). As expected, iron absorption was significantly lower from meals prepared from whole meal maize flour as compared to those prepared from refined flour (P < 0.001). For whole meal maize porridge, fractional absorption of iron from meals A, B and C was 1.31%, 3.12% and 2.30%, respectively. ConclusionsFractional absorption of iron from edible house crickets added to maize porridge was generally low, and addition of crickets to refined maize porridge reduced fractional iron absorption from the meal. Before promoting edible insects as an alternative source of iron, further investigation into their anti-nutritional properties is required. Funding SourcesWellcome Trust, UK.

Reprocessing of the old flotation tailings deposited on the RTB Bor tailings pond - a case study

Flotation waste, which was produced through seventy years of copper ore processing in RTB Bor, Serbia, is deposited in a flotation tailings pond. In total, almost 26.4 Mt could be considered as available for eventual reprocessing and reuse. Chemical analysis has shown that an average concentration of targeted metals in the tailings is: 0.183% Cu, 0.35 g/t Au and 2.17 g/t Ag. The tailings contain 60 to 70% of SiO2, 10 to 17% of Al2O3 and pyrite 5 to 8%. Flotation tailings reprocessing consisted of acid leaching followed by re-flotation of the leach residue. Leaching of the tailings resulted in leach liquors containing Cu2+ ions from 50 to 580 ppm. The average copper removal degree in the leaching stage was 70%. After re-flotation, the total copper removal degree reached 83 to 85%. Sulphur removal degree reached 77%. Sulphur concentration in the treated tailings was reduced almost 5 times compared to the inlet concentration. An equivalent amount of iron was also reduced through the flotation process. Concentration of total copper was reduced 3 times.

Use of Banded Hematite Quartzite (BHQ) in Blast Furnace for Partial Replacement of Quartzite

Hot metal produced through blast furnace (BF) route is still the most preferred route in majority of the steel industries. In the blast furnace operation, quartzite is used as flux to adjust the desired slag chemistry and basicity (B2 of 1–1.08) to achieve optimum slag properties such as low liquidus temperature, high Sulphur carrying capacity and low viscosity. This paper describes the investigations carried out at JSW Steel Ltd to identify alternate sources of silica other than quartzite for use as flux in BF to maintain the desired slag chemistry for smooth operation and cost reduction. Banded hematite quartzite (BHQ) ore available in Karnataka region contains 28–33% Fe, 45–46% silica, 1.3–1.5% alumina and is found suitable for use as partial replacement for quartzite in blast furnaces. Mineralogy and phase analysis of BHQ reveals alternate bands of hematite and silica whereas in lump ore, hematite and silica are uniformly distributed. This phase distribution and reducibility index of BHQ (~66%) affect the softening start temperature by forming fayalite (2FeO·SiO2) as primary slag. Fines generations are found to be comparatively higher (from 6.3 to 6.4%) but in acceptable range. The Fe content in the BHQ also contributes to the overall Fe input to the furnace favoring an option to reduce the equivalent amount of iron bearing materials in the charge. Plant trials at JSW steel blast furnace #4, indicate an improvement in overall operational performance resulting in increased Fe input per charge, reduction in slag rate by 8 kg/thm due to low alumina input and easier achievement of final slag chemistry.

Accessibility and Selective Stabilization of the Principal Spin States of Iron by Pyridyl versus Phenolic Ketimines: Modulation of the 6A1 ↔ 2T2 Ground-State Transformation of the [FeN4O2]+ Chromophore

Several potentially tridentate pyridyl and phenolic Schiff bases (apRen and HhapRen, respectively) were derived from the condensation reactions of 2-acetylpyridine (ap) and 2'-hydroxyacetophenone (Hhap), respectively, with N-R-ethylenediamine (RNHCH(2)CH(2)NH(2), Ren; R = H, Me or Et) and complexed in situ with iron(II) or iron(III), as dictated by the nature of the ligand donor set, to generate the six-coordinate iron compounds [Fe(II)(apRen)(2)]X(2) (R = H, Me; X(-) = ClO(4)(-), BPh(4)(-), PF(6)(-)) and [Fe(III)(hapRen)(2)]X (R = Me, Et; X(-) = ClO(4)(-), BPh(4)(-)). Single-crystal X-ray analyses of [Fe(II)(apRen)(2)](ClO(4))(2) (R = H, Me) revealed a pseudo-octahedral geometry about the ferrous ion with the Fe(II)-N bond distances (1.896-2.041 Å) pointing to the (1)A(1) (d(π)(6)) ground state; the existence of this spin state was corroborated by magnetic susceptibility measurements and Mössbauer spectroscopy. In contrast, the X-ray structure of the phenolate complex [Fe(III)(hapMen)(2)]ClO(4), determined at 100 K, demonstrated stabilization of the ferric state; the compression of the coordinate bonds at the metal center is in accord with the (2)T(2) (d(π)(5)) ground state. Magnetic susceptibility measurements along with EPR and Mössbauer spectroscopic techniques have shown that the iron(III) complexes are spin-crossover (SCO) materials. The spin transition within the [Fe(III)N(4)O(2)](+) chromophore was modulated with alkyl substituents to afford two-step and one-step (6)A(1) ↔ (2)T(2) transformations in [Fe(III)(hapMen)(2)]ClO(4) and [Fe(III)(hapEen)(2)]ClO(4), respectively. Previously, none of the X-salRen- and X-sal(2)trien-based ferric spin-crossover compounds exhibited a stepwise transition. The optical spectra of the LS iron(II) and SCO iron(III) complexes display intense d(π) → p(π)* and p(π) → d(π) CT visible absorptions, respectively, which account for the spectacular color differences. All the complexes are redox-active; as expected, the one-electron oxidative process in the divalent compounds occurs at higher redox potentials than does the reverse process in the trivalent compounds. The cyclic voltammograms of the latter compounds reveal irreversible electrochemical generation of the phenoxyl radical. Finally, the H(2)salen-type quadridentate ketimine H(2)hapen complexed with an equivalent amount of iron(III) to afford the μ-oxo-monobridged dinuclear complex [{Fe(III)(hapen)}(2)(μ-O)] exhibiting a distorted square-pyramidal geometry at the metal centers and considerable antiferromagnetic coupling of spins (J ≈ -99 cm(-1)).

Iron supplementation of breastfed infants

Reported here are three studies performed with the objective of finding ways to improve the iron status of breastfed infants and to prevent iron deficiency (ID). Participating infants were exclusively breastfed until 4 months of age; thereafter, they could receive complementary foods and, in some studies, supplemental formula. In the first study, infants were given medicinal iron between the ages of 1 and 5.5 months. During this period, iron status improved and ID was prevented; however, these benefits did not continue after the intervention ceased. In the second study, infants received medicinal iron or an equivalent amount of iron from an iron-fortified cereal between the ages of 4 and 9 months. Again, iron supplementation largely prevented ID from occurring, while non-anemic ID and ID anemia occurred in the control group as well as in the intervention groups before the intervention began. In the third study, infants received dry cereals fortified with electrolytic iron or with ferrous fumarate between the ages of 4 and 9 months. The cereals were equally effective in providing relative protection from ID. The results of these three studies indicate it is possible to protect breastfed infants from ID and IDA.

Transgenic Rice Is a Source of Iron for Iron-Depleted Rats

Iron deficiency is one of the most prevalent nutrient deficiencies in the world. A sustainable solution to dietary iron deficiency may be achieved in part by increasing bioavailable iron in seeds used for foods such as rice. Because ferritin is used as a natural source of iron in the early development of humans, other animals and plants, the bioavailability of iron in rice seeds, provided in amounts equal to ferrous sulfate, and in transgenic rice with ferritin was tested in iron-deficient rats. A standard hemoglobin (Hb) repletion bioassay was used with rats made anemic followed by complete diets containing equivalent amounts of iron as FeSO(4) or one of three different bioengineered rice varieties (Kitaake and two transgenic derivatives with ferritin targeted to the seed, FK11 and FK22). Rice diets were as effective as the FeSO(4) diet in replenishing hematocrit, Hb concentration and liver iron concentrations. These data suggest that Mendelian and biotechnological approaches to manipulating ferritin expression of seed iron in rice may contribute to a sustainable solution to global problems of iron deficiency.

Phase behavior of Eu(III) in fulvic acid-Fe(III)−H20 system at pH 1–9

The method was developed allowing quantitative extraction of fulvic acids from soil samples in the form close to native. Formation of gel-like and soluble forms of iron(III) fulvates in the systems containing equivalent amounts of iron(III) and fulvic acid was studied within pH range 1–9. The molecular structure of fulvates and the mechanism of transformation of gel to soluble forms was analyzed by IR spectroscopy. Distribution of microamounts of europium between gel-like iron fulvates and their solutions was studied. The correlation between phase distribution of europium and solubilization of iron(III) fulvates was analyzed.

Purified Ferritin and Soybean Meal Can be Sources of Iron for Treating Iron Deficiency in Rats

Ferritin and soybean meal were reevaluated as dietary treatments of iron deficiency in rats. Isotopes that had been used in the past were avoided because of contemporary knowledge of the physiological and structural complexity of ferritin protein and the solid iron mineral. Rats made anemic by iron-deficient diets were given equivalent amounts of iron as FeSO4, horse spleen ferritin, baked soybean meal, or soybean meal plus ferritin. Full recovery (89–109%) from anemia and increased tissue iron occurred after 28 d of treatment with any of the iron sources, which contrasts to past bioavailability studies using 59Fe-labeled ferritin and generally shorter periods of observation. Cultivar-specific variability was observed in soybean seed soluble iron and ferritin content (1.9–2.0 times the control cultivar, Arksoy), which was apparently heritable. The combined data suggest that manipulating ferritin expression and other soluble components of seed iron in soybeans and possibly other seeds, using Mendelian and biotechnological approaches, could contribute to a sustainable solution to global problems of iron deficiency.

Expression of Desulfovibrio gigas Desulforedoxin in Escherichia coli: PURIFICATION AND CHARACTERIZATION OF MIXED METAL ISOFORMS

The dsr gene from Desulfovibrio gigas encoding the nonheme iron protein desulforedoxin was cloned using the polymerase chain reaction, expressed in Escherichia coli, and purified to homogeneity. The physical and spectroscopic properties of the recombinant protein resemble those observed for the native protein isolated from D. gigas. These include an alpha 2 tertiary structure, the presence of bound iron, and absorbance maxima at 370 and 506 nm in the UV/visible spectrum due to ligand-to-iron charge transfer bands. Low temperature electron paramagnetic resonance studies confirm the presence of a high-spin ferric ion with g values of 7.7, 5.7, 4.1, and 1.8. Interestingly, E. coli produced two forms of desulforedoxin containing iron. One form was identified as a dimer with the metal-binding sites of both subunits occupied by iron while the second form contained equivalent amounts of iron and zinc and represents a dimer with one subunit occupied by iron and the second with zinc.

Microdetermination of L-ascorbic acid in pharmaceutical preparations by iodide ion-selective electrode and spectrophotometry

Two methods for determining low levels of L-ascorbic acid in pharmaceutical preparations are described. The potentiometric method is based on oxidation of an aqueous ascorbic acid solution with iodine in chloroform. The iodide ions produced in the aqueous phase are determined with the iodide ion-selective electrode using a standard calibration graph technique. The spectrophotometric method is based on oxidation of ascorbic acid with iron(III). The equivalent amount of iron(II) produced is determined as iron(II)-2,4,6-tri(2′-pyridyl)-triazine chelate at 595 nm. The results show a mean recovery of 100.067±0.1435 for the potentiometric method, 100.267±0.32 for the spectrophotometric method.

Crystalline ferredoxin from the photosynthetic bacterium Chromatium.

Abstract Ferredoxin has been isolated and crystallized from the photosynthetic bacterium Chromatium . It is similar to other ferredoxins in having an equivalent amount of iron and inorganic sulfide, a strongly electronegative oxidative-reduction potential and a capacity to substitute for native chloroplast ferredoxin in mediating the reduction of NADP + . Chromatium ferredoxin differs in its iron content and its more electronegative oxidation-reduction potential from the other ferredoxins that have been isolated so far.