Identification Of Iron Research Articles

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

Palladium-catalyzed Wacker-type reactions occupy a central place in organic synthesis with important implications in industry. Pursuing more benign protocols by replacing palladium with first-row transition metals allowed the identification of iron as a privileged one in the last few years. Although the anti-Markovnikov selectivity for iron catalysts is well developed, the Markovnikov-selective reactions still afford significant quantities of alcohol side-products, and identification of reaction intermediates has remained elusive so far. Herein, we present an iron catalyst that affords Markovnikov ketone products from (hetero)aromatic and aliphatic olefins in up to 99% selectivity under ambient conditions with 190,000 turnover numbers and turnover frequencies of 74 h–1 at 50 °C. The catalyst design is based on the promiscuous activity encountered in the family of the cytochromes P-450 enzymes, and it enables the formation of iron-hydride species under catalytically relevant reaction conditions. Substrate scope assessment and mechanistic investigations suggest that the Markovnikov-selective catalytic cycle competes with unprecedented three additional catalytic cycles (alcohol formation, hydrogenation, and reductive homo-coupling) depending on the nature of the olefin and the reaction conditions.

Identification of the different oxidation states of iron by using a formaldehyde clock system

In this paper, identification of iron with different oxidation states (Fe(Ⅵ), Fe(III) and Fe(II)) was firstly finalized by using a formaldehyde clock system (HCHO - NaHSO3 - Na2SO3), based on the different effects of analytes on the induction period. To put it simply, addition of K2FeO4 into the clock system made the induction period decrease while addition of FeCl3 made the induction period increase. Addition of FeCl2 had no effect on the induction period, but it reduced the slope of pH jump. Thus, these three analytes (K2FeO4, FeCl3 and FeCl2) could be identified in the concentration range of 2.0 × 10−4−1.2 × 10−3 mol L−1. Moreover, the quantitative detection of K2FeO4 and FeCl3 was realized according to the response of the induction period to the analytes concentration. The cyclic voltammetry (CV) results showed that only K2FeO4 and NaHSO3/Na2SO3 had redox reaction. The products obtained from the reactions of analytes with the clock system were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. Finally, the mechanisms of the response of the three analytes on the clock were proposed based on the experimental results.

Identification of iron and zinc responsive genes in pearl millet using genome-wide RNA-sequencing approach

Pearl millet (Pennisetum glaucum L.), an important source of iron (Fe) and zinc (Zn) for millions of families in dryland tropics, helps in eradicating micronutrient malnutrition. The crop is rich in Fe and Zn, therefore, identification of the key genes operating the mineral pathways is an important step to accelerate the development of biofortified cultivars. In a first-of-its-kind experiment, leaf and root samples of a pearl millet inbred ICMB 1505 were exposed to combinations of Fe and Zn stress conditions using the hydroponics method, and a whole-genome transcriptome assay was carried out to characterize the differentially expressed genes (DEGs) and pathways. A total of 37,093 DEGs under different combinations of stress conditions were identified, of which, 7,023 and 9,996 DEGs were reported in the leaf and root stress treatments, respectively. Among the 10,194 unique DEGs, 8,605 were annotated to cellular, biological, and molecular functions and 458 DEGs were assigned to 39 pathways. The results revealed the expression of major genes related to the mugineic acid pathway, phytohormones, chlorophyll biosynthesis, photosynthesis, and carbohydrate metabolism during Fe and Zn stress. The cross-talks between the Fe and Zn provided information on their dual and opposite regulation of key uptake and transporter genes under Fe and Zn deficiency. SNP haplotypes in rice, maize, sorghum, and foxtail millet as well as in Arabidopsis using pearl millet Fe and Zn responsive genes could be used for designing the markers in staple crops. Our results will assist in developing Fe and Zn-efficient pearl millet varieties in biofortification breeding programs and precision delivery mechanisms to ameliorate malnutrition in South Asia and Sub-Saharan Africa.

Coupling X-ray Absorption and Raman Spectroscopies to Characterize Iron Species in a Karst Pedosedimentary Record

The identification of iron (Fe) forms throughout a sediment sequence was investigated by X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) at the Fe K-edge, paired with Raman micro-spectroscopy. The contribution of different organic and inorganic Fe-bearing compounds was quantified by Linear Combination Fitting (LCF) carried out on both XANES and EXAFS spectra. Fe-XANES showed that the Fe(II)/Fe(III) ratio of different Fe-bearing minerals in sediments can be quantified with reasonable accuracy. The main Fe species detected were ferrihydrite, goethite, hematite, clay minerals (smectite, illite, nontronite), and Fe(III)-organic matter (Fe(III)-OM). A more accurate quantification of ferrihydrite was possible with LCF conducted on Fe-EXAFS spectra. With the exception of hematite, the concentration of these mineral species does not have a clear trend with depth, probably because water infiltration caused continuous Fe reduction and oxidation cycles in these sediments. From an analytical perspective, Fe oxide compounds can be difficult to identify or distinguish unless multiple techniques are used. X-ray diffraction (XRD; previous work) and Raman spectroscopy turn out to be not particularly useful in identifying ferrihydrite, while they are best suited for a broad mineralogical analysis that requires integrative spectral studies for an accurate Fe speciation. In detail, XANES and EXAFS allowed for the detection of Fe-bearing clay minerals and a more refined identification of Fe species, including Fe(III)-OM. Thermal analysis was useful to confirm some mineralogical components observed using both XRD (data previously published) and Raman spectroscopy (e.g., goethite, todorokite). In conclusion, this study underlines how a multi-technique approach is required to investigate peculiar environments such as karst pedosequences.

Identification of iron and sulfate release processes during riverbank filtration using chemical mass balance modeling.

Various hydrogeochemical processes can modify the quality of river water during riverbank filtration (RBF). Identifying the subsurface processes responsible for the bank-filtered water quality is challenging, but essential for predicting water quality changes and determining the necessity of post-treatment. However, no systematic approach for this has been proposed yet. In this study, the subsurface hydrogeochemical processes that caused the high concentrations of total iron (Fe) and sulfate (SO42-) in the bank-filtered water were investigated at a pilot-scale RBF site in South Korea. For this purpose, water quality variations were monitored in both the extraction well and the adjacent river over five months. The volumetric mixing ratio between the river water and the native groundwater in the RBF well was calculated to understand the effect of mixing on the quality of water from the well and to assess the potential contribution of subsurface reactions to water quality changes. To identify the subsurface processes responsible for the evolution of Fe and SO42- during RBF, an inverse modeling based on the chemical mass balance was conducted using the water quality data and the calculated volumetric mixing ratio. The modeling results suggest that pyrite oxidation by abundant O2 present in an unsaturated zone could be a primary process explaining the evolution of total Fe and SO42- during RBF at the study site. The presence of pyrite in the aquifer was indirectly supported by iron sulfate hydroxide (Fe(SO4)(OH)) detected in oxidized aquifer sediments.

Identification of iron by methods of cytochemical analysis in the spleen tissues during experimental radiation pathology

The article presents the results of studying the radio protective properties of alfalfa extract (dietary supplement "Erakond"). A decrease in the iron content in macrophages of the red pulp of the spleen was found experimentally using models of experimental radiation pathology induced by ɣ-irradiation of white rats in a single dose of 4 Gy at a dose rate of 1.7 Gy/min. The mechanisms of pathological processes in acute radiation pathology, leading to a decrease in the content of endogenous iron at the systemic, organ, cellular and subcellular levels, have been disclosed. Violation of the processes of enteral absorption of minerals as a result of pronounced destructive-inflammatory processes in the intestinal wall, damage to the hematopoiesis-inducing environment in the red bone marrow, inhibition of cytokine synthesis (IL-1, IL-3, IL-6, IL-7) and granulocytic macrophage colony-stimulating factor (GM-CSF) reduce the level of deposited iron in acute radiation pathology. In rats treated with 40 % "Erakond" aqueous extract before and after irradiation, there is a relatively high level of deposited iron in the spleen tissues in comparison with animals of the comparison group, which were on a general food ration.

Mini-metagenome analysis of psychrophilic electroactive biofilms based on single cell sorting

Understanding the metabolic function of psychrophilic electroactive bacteria is important for the investigation of extracellular electron transfer (EET) mechanisms under low temperatures (4–15 °C). In this study, Raman activated cell ejection coupled high throughput sequencing was used to accurately generate a mini-metagenome of psychrophilic bacterial community. Hierarchical cluster analysis of the Raman spectrum could accurately select the target Geobacter cluster. The high relative abundance of the membrane transport functional genes ftsEX in the biofilm community indicated an adaptation to reduced temperature, which aided survival of the electroactive bacteria under low temperature. The basal metabolism such as citrate cycle and glycolytic pathway maintained the electron pool for the EET process. The identification of iron (III) transport system genes in high abundance indicated their presence in an active metabolic reaction for potential electron transfer process. It showed the potential involvement c-type cytochromes (coxA and cox1) activity in EET. These results indicated that psychrophilic Geobacter had effective EET mediated by c-type cytochromes at low temperatures.

Engraved stone plaquettes from the North Patagonian area (Somuncurá plateau, Río Negro, Argentina) and the use of different microscopic techniques for their analysis

ABSTRACTThe aim of this paper is to present the first record of engraved stone plaquettes recovered at the Laguna Azul site (LA-P3) located in the Somuncurá plateau (Río Negro, Argentina). The stone plaquettes record is wide and varied in Argentina and especially in the North Patagonia region; however, it mostly consists of surface finds. The four plaquettes from LA-P3 are associated with Late Holocene dates (c.1906–1756 years BP) and in this paper the authors describe their designs and motifs, as complementary studies using different microscopy techniques. LA-P3’s plaquettes displayed red residues which were analysed by SEM-EDX and allowed identification of iron and titanium on their surfaces. This study contributes to the stone plaquette register of North Patagonia, and provides novel information related to their production techniques (mostly incision) and their motifs identified (non-figurative). The low frequency of similar motifs between the sets analysed allows us to propose a certain regionalization of their production.

Colorimetric Sensor Array for Detection of Iron(II) Ion

Sensor array methodology had attracted much attention because of its advantages in accuracy, diversity and capacities in simultaneous detection and discrimination of multiple analytes. In this study, a colorimetric sensor array comprising chloroauric acid and L-arginine mixture for the detection and identification of iron (II) ion is developed. Principal component analysis and hierarchical cluster analysis showed that the colorimetric sensor array had excellent discrimination capability to iron (II) ion. This research suggests that chloroauric acid and L-arginine mixture could act as cations chemosensor, which provides an alternative approach to design novel colorimetric sensor array. Keywords: Colorimetric sensor array, principal component analysis, hierarchical cluster analysis, cation, chloroauric acid, L-arginine.

Gastric siderosis: An under-recognized and rare clinical entity

The increased deposition of iron in gastric mucosa is known as gastric siderosis. It is believed that the only regulated step of the iron metabolism cycle occurs during absorption in the small intestine. Once this system becomes overwhelmed due to either local or widespread iron levels, then iron can be absorbed very quickly by a passive concentration-dependent mechanism. This excess iron is initially stored in the liver but later can be found in the pancreas, heart and joints. Excess iron is not expected to deposit in the gastric mucosa. This gastric deposition has been found in association with hemochromatosis, oral iron medications, alcohol abuse, blood transfusions, hepatic cirrhosis and spontaneous portacaval shunt with esophageal varices. The precise mechanism of this iron deposition in gastric epithelial and stromal cells is still not well understood; thus, identification of iron in gastric mucosa raises many questions. On histology, the pattern of deposition is variable, and recognition of the pattern is often useful to choose the appropriate workup for the patient and to diagnose and possibly treat the cause of iron overload. In this article, we have described a well-referenced review of this rare clinical entity with different histological patterns, diagnostic tests and the clinical significance of the different patterns of iron deposition.

Identification of iron and heme utilization genes in Aeromonas and their role in the colonization of the leech digestive tract.

It is known that many pathogens produce high-affinity iron uptake systems like siderophores and/or proteins for utilizing iron bound to heme-containing molecules, which facilitate iron-acquisition inside a host. In mutualistic digestive-tract associations, iron uptake systems have not been as well studied. We investigated the importance of two iron utilization systems within the beneficial digestive-tract association Aeromonas veronii and the medicinal leech, Hirudo verbana. Siderophores were detected in A. veronii using chrome azurol S. Using a mini Tn5, a transposon insertion in viuB generated a mutant unable to utilize iron using siderophores. The A. veronii genome was then searched for genes potentially involved in iron utilization bound to heme-containing molecules. A putative outer membrane heme receptor (hgpB) was identified with a transcriptional activator, termed hgpR, downstream. The hgpB gene was interrupted with an antibiotic resistance cassette in both the parent strain and the viuB mutant, yielding an hgpB mutant and a mutant with both iron uptake systems inactivated. In vitro assays indicated that hgpB is involved in utilizing iron bound to heme and that both iron utilization systems are important for A. veronii to grow in blood. In vivo colonization assays revealed that the ability to acquire iron from heme-containing molecules is critical for A. veronii to colonize the leech gut. Since iron and specifically heme utilization is important in this mutualistic relationship and has a potential role in virulence factor of other organisms, genomes from different Aeromonas strains (both clinical and environmental) were queried with iron utilization genes of A. veronii. This analysis revealed that in contrast to the siderophore utilization genes heme utilization genes are widely distributed among aeromonads. The importance of heme utilization in the colonization of the leech further confirms that symbiotic and pathogenic relationships possess similar mechanisms for interacting with animal hosts.

Principles and Imaging Technologies of Magnetic Resonance Phase Imaging

Magnetic resonance phase images are able to enhance contrast between gray and white matter and between water and fat by using differences of susceptibility between tissues.Phase images are suitable for the identification of iron and for visualizing veins.In this paper,two basic phase imaging technologies,susceptibility weighted imaging and quantitative susceptibility mapping,were reviewed.

Arsenic mobilization in alluvial soils of Punjab, North–West India under flood irrigation practices

A laboratory investigation was carried out to examine the mechanism of arsenic (As) mobilization under flooded conditions (24 and 240 h) in 18 alluvial soils of Punjab, North–West India. Total dissolved As increased from a range of 3–16 μg L−1 (mean 9 μg L−1) to a range of 33–1,761 μg L−1 (mean 392 μg L−1) with the increase in flooding period from 24 to 240 h. The amount of As mobilization varied depending upon redox potential (pe) created by flooding conditions. After 24 h of flooded conditions, pe of soil water suspension ranged from −1.75 to 0.77 (mean −0.24). Increasing the flooding period to 240 h, pe of soil water suspension decreased in the range of −4.49 to −2.74 (mean −3.29). Pourbaix diagram identified arsenate (HAsO4 2−) as predominant species in most of the alluvial soil–water suspensions under oxidized conditions, after 24 h of equilibration period, which ultimately transformed to arsenite (H3AsO3 0) after 240 h of anaerobic condition due to more reduced status. The solid phase identified was orpiment (As2S3). Identification of iron and manganese species in alluvial soil water suspension by Pourbaix diagram indicated decline in both soluble Fe2+ and SO4 2− concentration due to the formation of iron sulfide mineral phase after 240 h under anaerobic conditions. In these soils, decline in soluble Fe was also due to the precipitation of vivianite [Fe3(PO4)2·8H2O]. Elevated arsenic content and low pe value were measured in aquifers located in paddy growing fields comparative to aquifers of other sites. Large degree of variability in As concentrations was recorded in aquifers located at same sites. Thus, it is better to analyze each aquifer for their As content rather than to depends on the prediction on As content of neighbouring wells. The present investigation elucidates that flood irrigation practices in Punjab for growing paddy crop could induce the geochemical conditions favorable to mobilize arsenic from surface soils which could eventually elevate its content in the underlying shallow aquifers. Water abstracted from these aquifers by hand pumps or tube wells for drinking purposes could create hazards for local population due to loading with arsenic concentration above the safe limits. Thus, to avoid further contamination of shallow aquifers with arsenic, it is advisable to shift the flooded rice cultivation to other upland crops having lesser water requirement.

Identification of mineral deposits in the brain on radiological images: a systematic review

MRI has allowed the study of mineral deposition in the brain throughout life and in disease. However, studies differ in their reporting of minerals on MRI for reasons that are unclear. We conducted a systematic review from 1985 to July 2011 to determine the appearance of iron, calcium, copper and manganese on MRI and CT and their reliability. We assessed which imaging investigations provided the most consistent results compared with histology. Of 325 papers on minerals imaging, we included 46 studies that confirmed findings either directly or indirectly using a non-imaging method such as histology. Within this group, there was inconsistency in the identification of iron probably because of changes in its paramagnetic properties during its degradation. Iron appeared consistently hypointense only on T2*-weighted MRI, and along with calcified areas, hyperattenuated on CT. Appearance of copper, calcium and manganese, although consistently reported as hyperintense on T1-weighted MRI, was confirmed histologically in few studies. On T2-weighted imaging, calcified areas were always reported as hypointense, while the appearance of iron depended on the concentration, location and degradation stage. More work is required to improve the reliability of imaging methods to detect and differentiate brain mineral deposition accurately. There is inconsistency in reporting the appearance of minerals on radiological images. • Only 46 studies confirmed mineral appearance using a non-imaging method. • Iron is the mineral more widely studied, consistently hypointense on T2*-weighted MRI. • T1-weighted MRI consistently reported copper, calcium and manganese hyperintense. • Calcium is consistently reported hypointense on T2-weighted MRI and hyperattenuating on CT.

Research on Experiment and Technique of Material Identification for Debris of Engineering Equipment Based on Computer Vision

Based on micro-image, the material identification of iron and copper debris in working oil of engineering equipment is researched. By selecting four characteristic parameters of debris image, a debris recognition classifier is designed based on multi-SVM. The materials and types of debris can be fast identified after the model is trained and the identification accuracy is high, thus a new method for fault diagnosis of engineering equipment is provided.

Tracking iron in multiple sclerosis: a combined imaging and histopathological study at 7 Tesla

Previous authors have shown that the transverse relaxivity R(2)* and frequency shifts that characterize gradient echo signal decay in magnetic resonance imaging are closely associated with the distribution of iron and myelin in the brain's white matter. In multiple sclerosis, iron accumulation in brain tissue may reflect a multiplicity of pathological processes. Hence, iron may have the unique potential to serve as an in vivo magnetic resonance imaging tracer of disease pathology. To investigate the ability of iron in tracking multiple sclerosis-induced pathology by magnetic resonance imaging, we performed qualitative histopathological analysis of white matter lesions and normal-appearing white matter regions with variable appearance on gradient echo magnetic resonance imaging at 7 Tesla. The samples used for this study derive from two patients with multiple sclerosis and one non-multiple sclerosis donor. Magnetic resonance images were acquired using a whole body 7 Tesla magnetic resonance imaging scanner equipped with a 24-channel receive-only array designed for tissue imaging. A 3D multi-gradient echo sequence was obtained and quantitative R(2)* and phase maps were reconstructed. Immunohistochemical stainings for myelin and oligodendrocytes, microglia and macrophages, ferritin and ferritin light polypeptide were performed on 3- to 5-µm thick paraffin sections. Iron was detected with Perl's staining and 3,3'-diaminobenzidine-tetrahydrochloride enhanced Turnbull blue staining. In multiple sclerosis tissue, iron presence invariably matched with an increase in R(2)*. Conversely, R(2)* increase was not always associated with the presence of iron on histochemical staining. We interpret this finding as the effect of embedding, sectioning and staining procedures. These processes likely affected the histopathological analysis results but not the magnetic resonance imaging that was obtained before tissue manipulations. Several cellular sources of iron were identified. These sources included oligodendrocytes in normal-appearing white matter and activated macrophages/microglia at the edges of white matter lesions. Additionally, in white matter lesions, iron precipitation in aggregates typical of microbleeds was shown by the Perl's staining. Our combined imaging and pathological study shows that multi-gradient echo magnetic resonance imaging is a sensitive technique for the identification of iron in the brain tissue of patients with multiple sclerosis. However, magnetic resonance imaging-identified iron does not necessarily reflect pathology and may also be seen in apparently normal tissue. Iron identification by multi-gradient echo magnetic resonance imaging in diseased tissues can shed light on the pathological processes when coupled with topographical information and patient disease history.

Identification of Iron Rusts on Rail by X-Ray Diffraction and Vibrational Analysis

A periodical unevenness of the running surface of rails is formed on ascending slope of submarine railway tunnel. One of the causes has been concluded due to the combination of a low friction and wheel load variation induced by some kinds of iron oxides and oxyhydroxides with various coefficients of friction on the rail, though it has not been made clear yet. In this study, X-ray diffraction and Raman scattering spectroscopic analysis were attempted to identify iron rusts on the rail as a process to solve the periodic unevenness of the rail suffering many railway companies.

Targeted identification of iron regulated genes in patients with hemochromatosis and hepatitis C using a whole genome cDNA microarray

Targeted identification of iron regulated genes in patients with hemochromatosis and hepatitis C using a whole genome cDNA microarray

Identification of Iron−Cyanide Complexes in Contaminated Soils and Wastes by Fourier Transform Infrared Spectroscopy

Persistent cyanide species in soil are mainly iron-cyanide (Fe-CN) complexes. They originate from anthropogenic inputs of compounds such as Fe4[Fe(II)(CN)6]3 in deposited gas-purifier wastes (GPW) or K2Zn3[Fe(II)(CN)6]2 in deposited blast-furnace sludge (BFSI). Fe-CN species in de-inking sludge (DIS) and sewage farm soils (SF) are still unknown. We investigated 35 soil and waste samples from 15 European sites and five synthesized Fe-CN-containing compounds by Fourier transform infrared spectroscopy. Furthermore, we determined the contents of total and adsorbed CN and pH. In all samples (pH 2.2-9.5), adsorbed Fe-CN complexes were negligible. In GPW and DIS samples, Fe4[Fe(II)(CN)6]3 and KFe[FeII(CN)6] were the only Fe-CN compounds (total CN contents 0.4-449 g kg(-1)). Several BFSI samples were free of CN. The spectra of other BFSI samples partially indicated dissolution of the characteristic compound K2Zn3[Fe(II)(CN)6]2, resulting in a loss of CN (contents < 12.3 g kg(-1)). Distinctive changes in BFSI with respect to CN speciation occurred within relatively short periods, <20 years. Dissolution of K2Zn3[Fe(II)(CN)6]2 was followed by dissociation of free CN from [Fe(CN)6](3-/4-) and adsorption of [Fe(II)(CN)6](4-) on organic surfaces. In DIS and SF samples, Fe4[Fe(11)(CN)6]3 and K2Zn3[Fe(II)(CN)6]2 (SF only) were identified.

Molecular genetic approaches to increasing mineral availability and vitamin content of cereals

The present paper summarizes the current state of knowledge on molecular genetic approaches to increasing iron and zinc availability and vitamin content in cereals. We have also attempted to integrate the scientific issues into the wider context of human nutrition. In the cereal grain, iron and zinc are preferentially stored together with phytate in membrane-enclosed globoids in the protein storage vacuole (PSV) found in the aleurone and the embryo scutellum. The PSV is accordingly central for understanding mineral deposition during grain filling and mobilization of minerals during germination. Recent studies in Arabidopsis have led to the first identification of iron and zinc transporters of the PSV and further illustrate some of the dynamics associated with mineral and phytate transport and deposition into the vacuole. This provides new opportunities for modulating iron and zinc deposition in the cereal grain. Current strategies towards increasing the iron content of the endosperm are largely based on the expression of legume ferritin genes in an endosperm-specific manner. However, it is apparent that this approach, at least in rice, only allows a two- to three-fold increase in the iron content of the grain due to exhaustion of the iron stores in leaves. Further increases thus have to rely on additional uptake and transport of iron from the root. Phytate is generally considered to be the single most important anti-nutritional factor for iron and zinc availability. In the current paper we summarize attempts to increase phytase activity in the grain by transformation and evaluate the potential of this approach as well as the reduction of phytate biosynthesis for improving the bioavailability of iron and zinc. Vitamins constitute the second important group of micronutrients in grain and we discuss current efforts to increase the amounts of provitamin A, vitamin C and vitamin E.