Iron Moieties Research Articles

Regulation of extracellular electron transfer by sustained existence of Fe²⁺/Fe³⁺ redox couples on iron oxide-functionalized woody biochar anode surfaces in bioelectrochemical systems

Sluggish extracellular electron transfer between the exoelectrogens and anode interface limits the application of bioelectrochemical systems (BECs) for energy generation. In this study, an innovative anode coated with oxidized biochar and co-functionalized with iron nanoparticles (FBC/Fe2O3) was developed to enhance microbial reactions through tuned physicochemical and electrical properties. The designed anode features a highly porous, heterogeneous structure with a large accessible surface area of 10.141 m²/g, promoting better habitation and metabolism of exoelectrogens. The synergistic effect of iron nanoparticles and oxidized functional groups increased the hydrophilicity of the anode surface, augmenting its affinity for bacterial outer membrane c-cysts and facilitating microbial adhesion at a density of 3.106 × 10⁹ CFU/cm². The iron moieties on the FBC/Fe2O3 electrode surface act as electron mediators, utilizing Fe²⁺/Fe³⁺ redox couples, as evidenced by X-ray photoelectron spectroscopy (XPS) data. This enhancement improved extracellular electron transfer (EET) between bacterial cells and the anode surface, resulting in a faster and bifurcated EET process through both direct transfer via outer membrane c-cysts and mediated transfer via the redox couples of Fe moieties. The assembled double-chamber microbial fuel cell (DC-MFC) with the FBC/Fe2O3 anode achieved a maximum power density of 528.75 mW/m² and a chemical oxygen demand (COD) removal efficiency of 47.5 % within 24 h of operation.

Lignin regulating the active sites and peroxymonosulfate activation capacities of iron incorporated 1D carbon nanofiber for efficient organic pollutant degradation

In this study, 1D iron incorporated carbon nanofiber composite catalysts (PLCF-Fe) were prepared by pyrolyzing iron nitrate embedded polyacrylonitrile/lignin electrospun nanofiber. PLCF-Fe exhibited prominent peroxymonosulfate (PMS) activation capability for organic pollutant degradation, in which 1D structured carbon nanofiber effectively inhibited the aggregation of iron moieties. The introduction of lignin could modulate the oxidation capacities of the prepared PLCF-Fe through regulating both the graphitic degree as well as the oxygen-containing group distributions of the carbon nanofiber, and the crystalline phase composition of the iron compounds in PLCF-Fe. The existence of multiple active sites could concertedly trigger radical and non-radical PMS activation for high-efficient pollutant degradations, during which process negligible iron ions were leached. It was also found that pollutant degradation rate in PLCF-Fe/PMS system was correlated well with their highest occupied molecular orbital positions. Additionally, PLCF-Fe/PMS system could maintain conspicuous catalytic performance in a variety of water matrices with wide pH application range. This study provides an applicable structure and active sites regulating approach to prepare high-efficiency heterogeneous catalyst for PMS based Fenton-like organic decontamination processes.

Superoxide signalling and antioxidant processing in the plant nucleus.

The superoxide anion radical (O2·-) is a one-electron reduction product of molecular oxygen. Compared with other forms of reactive oxygen species (ROS), superoxide has limited reactivity. Nevertheless, superoxide reacts with nitric oxide, ascorbate, and the iron moieties of [Fe-S] cluster-containing proteins. Superoxide has largely been neglected as a signalling molecule in the plant literature in favour of the most stable ROS form, hydrogen peroxide. However, superoxide can accumulate in plant cells, particularly in meristems, where superoxide dismutase activity and ascorbate accumulation are limited (or absent), or when superoxide is generated within the lipid environment of membranes. Moreover, oxidation of the nucleus in response to environmental stresses is a widespread phenomenon. Superoxide is generated in many intracellular compartments including mitochondria, chloroplasts, and on the apoplastic/cell wall face of the plasma membrane. However, nuclear superoxide production and functions remain poorly documented in plants. Accumulating evidence suggests that the nuclear pools of antioxidants such as glutathione are discrete and separate from the cytosolic pools, allowing compartment-specific signalling in the nucleus. We consider the potential mechanisms of superoxide generation and targets in the nucleus, together with the importance of antioxidant processing in regulating superoxide signalling.

Syntheses, Structures and Reactivity of Metal Complexes of Trindane, Trindene, Truxene, Decacyclene and Related Ring Systems: Manifestations of Three-Fold Symmetry

The triple condensation of cyclopentanone or indanone to trindane (C15H18) or truxene (C27H18), respectively, provides convenient access to molecular skeletons on which major fragments of the prototypical fullerene C60 can be assembled. In particular, early approaches (both organic and organometallic) towards sumanene, as well as the final successful synthesis, are described. Organometallic derivatives of trindane have been prepared in which Cr(CO)3, Mo(CO)3, [Mn(CO)3]+ or [(C5H5)Fe(CO)2]+ are η6-bonded to the central arene ring. The debromination of hexabromotrindane yields trindene, which forms a tri-anion to which as many as three organometallic fragments, such as Mn(CO)3, W(CO)3Me, or Rh(CO)2, may be attached. Truxene forms complexes whereby three metal fragments can bind either to the peripheral arene rings, or to the five-membered rings, and these can be interconverted via η6 ↔ η5 haptotropic shifts. Truxene also forms a double-decker sandwich with Ag(I) bridges, and decacyclene, C36H18, forms triple-decker sandwiches bearing multiple cyclopentadienyl-nickel or -iron moieties. The organic chemistry of trindane has been investigated, especially with respect to its unexpectedly complex oxidation products, which were only identified unambiguously via X-ray crystallography. The three-fold symmetric trindane framework has also been used as a template upon which a potential artificial receptor has been constructed. Finally, the use of truxene and truxenone derivatives in a wide range of applications is highlighted.

SYNTHESIS OF UREA AND MAGNETITE-BASED CHITIN AS ADSORBENTS FOR THE REMOVAL OF AMLODIPINE BESYLATE

Objective: Development of urea and magnetite-based chitin adsorbents for the removal of amlodipine besylate. Methods: Amlodipine is a calcium channel blocker widely used to treat hypertension and angina. However, it is important to treat the residues before disposal so they do not pollute the effluent water sources. The amlodipine sorption property of chitin-based subtract (CBS) was improved by treatment with magnetite and urea, followed by pyrolysis at 500 °C. The FT-IR characterization, elemental composition, pore properties, and sorption isotherms were also assessed. Results: The sorption capacity of amlodipine increased from 4.6 to 9.3 mg/g for the urea and magnetite-treated products, respectively. Further, modified chitin products showed a pore volume (micro and mesopore composition), pore percentage, and roughness of 0.01 cm3g-1, 0.02 cm3g-1, 32% and 68%, and 1.2, respectively. The CBS and derivatives did not present Langmurian behavior, indicating a characteristic heterogeneous surface and the presence of energetically distinct sorption sites. The sorption equilibrium was achieved within 5 min, resulting in a net physical sorption. Conclusion: The insertion of nitrogen and iron moieties on the surface of chitin improved the adsorption capacity of amlodipine.

Formation of polynuclear iron(III) complexes of N-(2-pyridylmethyl)iminodipropanol depending on pseudohalide ions: synthesis, crystal structure, and magnetic properties

Five polynuclear iron(III) complexes, [(pmidp)Fe(NCSe)]2 (1), [(pmidp)Fe(NCBH3)]2 (2), [(Hpmidp/pmidp)Fe3(CH3O)2(NCS)4]∙H2O (3), [(pmidp)2Fe6(CH3O)4(N3)4(CH3COO)2O2] (4), and [(pmidp)2Fe6(CH3O)4(NCO)4(CH3COO)2O2]∙2MeOH (5) were isolated through the reactions of N-(2-pyridylmethyl)iminodipropanol (H2pmidp) and iron(III) ions with different pseudohalide ions. The complexes were studied via X-ray crystal diffraction, Mössbauer spectra, and magnetochemistry. The molecular structures of 1 and 2 were formed as the {Fe2(µ2-Opropoxo)2}2+ cores with pmidp2− and NCSe−/NCBH3−. The structure of 3 was formed as a {Fe3(µ2-OCH3)2(µ2-Opropoxo)4}5+ core with Hpmidp−/pmidp2− and NCS−. The structures of 4 and 5 were formed as {Fe6(µ4-O)2(µ2-OCH3)2(η2-OAc)2(µ2-Opropoxo)4} cores with pmidp2− and NCO−/N3−. Structural analyses revealed that the formation of various multinuclear iron(III) moieties depends on the auxiliary ligands. The oxidation states of all the complexes were confirmed as + 3 using the bond valence sum (BVS) calculations and Mössbauer spectral data. The susceptibility data for 1–5 fitted using each spin coupling (J) model indicated that 1–3 showed antiferromagnetic exchange interactions, and 4 and 5 showed the ferromagnetic and antiferromagnetic couplings, simultaneously.

Berberine Loaded Magnetic Nanoparticles for Breast Cancer Therapy on MDA-MB-231 Cells Lines

Berberine is an alkaloid naturally-derived from Berberis aristata and a family Berberidaceae exhibits a broad spectrum of pharmacological benefits, including antiviral and anticancer properties. The recent development of nanomedicine is an art of delivering drugs to the target-site by improving their safety and efficacy. In present study, four berberine-loaded magnetic nanoparticles (BBR/MNPs) were prepared using a modified co-precipitation method with calcination. The resulting BBR/MNPs were characterized by FTIR, XRD, HRSEM, zeta potential, VSM, loading efficiency, stability and in vitro release studies. The most proven magnetic nanoparticles formulation type in dissolution was followed by in vitro anticancer studies on MDA-MB-231 cells. XRD, FTIR and TGA results proved that the formed BBR/MNPs were ordered in their structure with iron, silanol groups and berberine moieties. The HRSEM reported the average particle size of MNPs varies from 100 to 250 nm after loading with berberine also had a regular spherical shape. The value of the zeta potential was -9 mV and 15 mV at pH 6 for bare MNPs and BBR/MNPs, respectively. Loading efficiency and stability were good at BBR/MCM-41MNP. The saturated magnetization (Ms) value of Fe-MCM-41 MNP (81.76 emu/g) was obtained by VSM analysis. In vitro dissolution studies of four BBR/MNPs at a three different pH 5.5, 6.5, 7.4 including BBR/MCM-41 MNP were 86%, 84% and 82%, respectively. In vitro anticancer studies with BBR/MCM-41-MNP on treated MDA-MB-231 breast cancer cells in comparison to standard doxorubicin. The MTT assay confirmed the cytotoxic effect of BBR/MCM-41-MNP in vitro. The resulting data were statistically analyzed using one-way Anova analysis with N = 3 replicates. The IC50 values (mean standard deviation) of BBR, BBR/MCM-41 MNP and standard doxorubicin were obtained as 16.754 ± 0.651, 6.750 ± 0.048, 4.955 ± 0.042 μg/mL with significant p < 0.0001. The best result was BBR/MCM-41 MNP with an average particle size 50 nm, which showed good drug loading efficiency and size stability above 7 days. Drug release was maximal (86%) at pH 5.5. The MTT-assay confirmed that BBR/MCM-41MNP exhibited more cytotoxicity on MDA-MB-231 cells than BBR, MCM-41MNP. The IC50 of BBR/MCM-41 was closed that of standard doxorubicin. The BBR/MCM-41MNP showed the optimum drug release with potent anticancer activity along with magnetic targeting.

A Fe-N/FeS@C composite prepared via mechanical activation and pyrolysis for sulfite activation to degrade organic contaminants: Single atomic irons anchored into carbon matrix with encapsulated FeS nanoparticles

A novel structural composite (Fe-N/FeS@C) was synthesized via a self-doping strategy by the pyrolysis of a solid mixture of lignosulfonate and ferric nitrate pretreated by mechanical activation. The as-synthesized composite contained 7.5 wt% of single atomic iron moieties and 16.0 wt% of encapsulated FeS nanoparticles, with a high surface area of 1095.81 m2 g–1 and plentiful micropores and mesopores (0.4–10 nm). The Fe-N/FeS@C composite was confirmed to possess outstanding catalytic activity for sulfite activation in the degradation of methylene blue, with a high reaction rate constant (0.77 g g–1 min–1) and long cycling stability (83.1% of initial activity retention after 10 recycles). Moreover, the composite exhibited satisfactory activity recovery via a simple rinsing process with ethanol and HCl, and performed well in a wide pH range of 3–11. Density functional theory calculation results further demonstrated that the reaction energy of the rate-determining step, in which SO3•− was produced from SO32– on atomic Fe moieties, was lower than that of the formation of FeSO3+ by Fe3+ and SO32–. The excellent performance of Fe-N/FeS@C was mainly attributed to the combination of the high mass loading of active sites of atomic Fe moieties anchored into carbon matrix with encapsulated FeS nanoparticles. This study provides new insight into the development of environment-friendly, stable and atomic dispersion iron composite for sulfite activation to efficiently remove organic pollutants.

Design of Organoiron Dendrimers Containing Paracetamol for Enhanced Antibacterial Efficacy.

Paracetamol (acetaminophen) is a common painkiller and antipyretic drug used globally. Attachment of paracetamol to a series of organoiron dendrimers was successfully synthesized. The aim of this study is to combine the benefits of the presence of these redox-active organoiron dendrimers, their antimicrobial activities against some human pathogenic Gram-positive, and the therapeutic characteristics of paracetamol. The antimicrobial activity of these dendrimers was investigated and tested with a minimum inhibitory concentration and this has been reported. Some of these newly synthesized dendrimers exhibited the highest inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and Staphylococcus warneri compared to reference drugs. The results of this study indicate that the antimicrobial efficacy of the dendrimers is dependent on the size of the redox-active organoiron dendrimer and its terminal functionalities. The best result has been recorded for the fourth-generation dendrimer 11, which attached to 48 paracetamol end groups and has 90 units composed of the η6-aryl-η5-cyclopentadienyliron (II) complex. This dendrimer presented inhibition of 50% of the growth (IC50) of 0.52 μM for MRSA, 1.02 μM for VRE, and 0.73 μM for Staphylococcus warneri. The structures of the dendrimers were characterized by elemental analysis, Fourier transform infrared (FT-IR), nuclear magnetic resonance (1H-NMR), and 13C-NMR spectroscopic techniques. In addition, all synthesized dendrimers displayed good thermal stability in the range of 300–350 °C following the degradation of the cationic iron moieties which occurred around 200 °C.

A Precursor Approach for the Development of Lace-like Fe2O3 Nanocrystallites Triggered by Pressure Dependent Nucleation and Growth of Akaganeite over Clay Based Composites for Toluene Combustion

Embedded catalysts for toluene combustion, featuring iron oxide (FeOx) moieties on the surface of clay derived porous heterostructural supports (PCH) were developed. The nucleation and growth of Fe4Cl0.44O3.56(OH)4.44(H2O)0.2 (akaganeite) in the function of Fe precursor interaction with the support entailed creation of nanostructured Fe oxides on the PCH surface. The hydrothermal forcing of ions migration and thermal transformation of as-synthesized Fe-PCH altered the surface composition and crystallinity of the formed nanostructured Fe oxides, thereby affecting the advantageous effects of donation gauged by electronic transfer. The polymorphism of Fe oxides created on PCH supports resulted in diverse catalytic activity of toluene combustion. Analysis of XPS Fe 2p core excitations showed that elongation of crystallization time of iron moieties on as synthesized Fe-PCH, as well as shortening of the annealing time, led to highly oxidized Fe species, mainly in the form of an α-Fe2O3 phase. Pressure dependent...

First Example of Cationic Cyclopentadienyliron Based Chromene Complexes and Polymers: Synthesis, Characterization, and Biological Applications

The present work encompasses development of a new class of active antimicrobial agents of the ɳ6-arene-ɳ5-cyclopentadienyliron (II) complexes and polymers to expand the existing family of antimicrobials. The design of the first example of these cationic organoiron complexes, incorporating chromene moieties, was successfully accomplished in good yield via the Steglich esterification, followed by the nucleophilic aromatic substitution reactions to isolate their polymeric analogues. Meanwhile, the structural identities of the new materials were confirmed using 1H and 13C NMR, IR, and elemental analysis. The molecular weight of the new polymeric materials was estimated using viscosity measurements, and was found to be in the range of 10,000 and 31,000. The chromene-containing organoiron complexes displayed reversible reduction behaviors as their functionalized polymers. Meanwhile, the TGA thermogram revealed initial weight losses due to the cleavage of the cationic iron moieties, while the second weight losses were dependent upon the etheric linkages in the polymer backbones. This study, therefore, focuses on the exploration of the antimicrobial and antitumor performance of the new materials along with their structure activity relationship.

Mononuclear iron-dependent electrocatalytic activity of metal-nitrogen-carbon catalysts for efficient oxygen reduction reaction

As a low-cost nonprecious metal-based catalyst, the mononuclear iron embedded in nitrogen-doped carbons has been regarded as one type of the best electrocatalytic materials for the oxygen reduction reaction (ORR). Herein, we proposed a silica-protective-layer assisted strategy for fabricating the catalysts with mononuclear iron site coordinated with adjacent nitrogen and carbon atoms, through high temperature pyrolysis of melamine, carbon black and FeCl3. At 800 °C, the fabricated catalyst features completely atomic level iron-nitrogen-carbon catalysts without Fe-based phases. In concentrated 1 M NaOH solution, this catalyst displays a remarkably improved catalytic activity with half-wave potential of 0.90 V. The mass activity of catalyst can reach 1.06 times that of commercial Pt/C (20 wt%, Pt). The correlation of the mononuclear iron composition and coordination structure with the promoted ORR kinetics was discussed in detail. The superior activity can be attributed to lots of the mononuclear iron moieties with a non-planar Fe(II)-N4 structure and increased surface area of the as-synthesized heterogeneous catalyst.

PGM-Free ORR Catalysts Designed by Templating PANI-Type Polymers Containing Functional Groups with High Affinity to Iron

In this work, a coordination-chemistry approach was used to increase the content of nitrogen-coordinated iron moieties (Fe-Nx) in platinum group metal-free (PGM-free) catalysts for oxygen reduction reaction (ORR). The catalysts were derived from a series of polyaniline (PANI)-type precursors with N-containing functional side chains having high affinity to iron. The PGM-free ORR catalysts synthesized using such polymeric templates were characterized by scanning electron microscopy, X-ray diffractometry, and tested in an electrochemical cell and H2-air fuel cell for ORR activity. X-ray photoelectron spectroscopy (XPS) analysis showed that, in spite of similar nitrogen contents, catalysts obtained using PANI-type polymers containing side chains with high affinity to iron had higher Fe content than PANI-derived catalyst. These PGM-free catalysts showed improved ORR activity in an electrochemical cell and in H2-air fuel cell testing, compared to the PANI-derived catalyst. A correlation between the content of Fe-Nx moieties and the fuel cell performance was observed in these PGM-free ORR catalysts.

Silicalite‐1 Encapsulated Fe Particles over an In‐situ Crystal Process for Syngas to Gasoline with Low CO2 Selectivity

AbstractZeolite synthesis involved use of large volumes of solvent that resulted in waste and enhanced production costs. In our study, we selected a solvent‐free synthesis route that involved mixing, grinding and crystallization at various times creating Fe@Silicalite‐1. This synthesis method produced a hierarchical in‐situ microporous crystal morphology with Fe particles caged inside zeolite displaying a high gasoline (C5‐C11) selectivity of 66.0% with a relatively low CO2 and CH4 selectivity (18.5% and 10.0%, respectively) in Fischer‐Tropsch synthesis. Prolonged crystallization time of 72 h and other subsequent procedures contributed to zeolite structure and performance. Iron moieties were appropriately immobilized over silicalite support. The characterization results were correlated with the zeolite activity and selectivity. This novel zeolite at its best possesses all the potential to be advanced in other related material synthesis because of its expedient procedure, characteristics and worthwhile outcomes.

Investigation of Earth-Abundant Oxygen Reduction Electrocatalysts for the Cathode of Passive Air-Breathing Direct Formate Fuel Cells

The development of direct formate fuel cells encounters important obstacles related to the sluggish oxygen reduction reaction (ORR) and low tolerance to formate ions in Pt-based cathodes. In this study, electrocatalysts formed by earth-abundant elements were synthesized, and their activity and selectivity for the ORR were tested in alkaline electrolyte. The results showed that carbon-encapsulated iron-cobalt alloy nanoparticles and carbon-supported metal nitrides, characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD), do not present significant activity for the ORR, showing the same half-wave potential of Vulcan carbon. Contrarily, nitrogen-doped carbon, synthesized using imidazole as the nitrogen source, showed an increase in the half-wave potential, evidencing an influential role of nitrogen in the ORR electrocatalysis. The synthesis with the combination of Vulcan, imidazole, and iron or cobalt precursors resulted in the formation of nitrogen-coordinated iron (or cobalt) moieties, inserted in a carbon matrix, as revealed by X-ray absorption spectroscopy (XAS). Steady-state polarization curves for the ORR evidenced a synergistic effect between Fe and Co when these two metals were included in the synthesis (FeCo-N-C material), showing higher activity and higher limiting current density than the materials prepared only with Fe or Co. The FeCo-N-C material presented not only the highest activity for the ORR (approaching that of the state-of-the-art Pt/C) but also high tolerance to the presence of formate ions in the electrolyte. In addition, measurements with FeCo-N-C in the cathode of an passive air-breathing direct formate fuel cells, (natural diffusion of formate), showed peak power densities of 15.5 and 10.5 mW cm−2 using hydroxide and carbonate-based electrolytes, respectively, and high stability over 120 h of operation.

The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation.

Cytochrome c oxidase (CcO) is a membrane protein of the respiratory chain that catalytically reduces molecular oxygen (O2) to water while translocating protons across the membrane. The enzyme hosts two copper and two heme iron moieties (heme a/heme a3). The atomic details of the sequential steps that go along with this redox-driven proton translocation are a matter of debate. Particularly for the reductive phase of CcO that precedes oxygen binding experimental data are scarce. Here, we use CcO under anaerobic conditions where carbon monoxide (CO) is bound to heme a3 which in tandem with CuB forms the binuclear center (BNC). Fourier-transform infrared (FTIR) absorption spectroscopy is combined with electro-chemistry to probe different redox and protonation states populated by variation of the external electrostatic potential. With this approach, the redox behavior of heme a and the BNC could be separated and the corresponding redox potentials were determined. We also infer the protonation of one of the propionate side chains of heme a3 to correlate with the oxidation of heme a. Experimental changes in the local electric field surrounding CO bound to heme a3 are determined by their vibrational Stark effect and agree well with electrostatic computations. The comparison of experimental and computational results indicates that changes of the heme a3/CuB redox state are coupled to proton transfer towards heme a3. The latter supports the role of the heme a3 propionate D as proton loading site.

Antimicrobial and anticancer activities of organoiron melamine dendrimers capped with piperazine moieties

Three generations of a biologically active class of melamine dendrimers containing arene- cyclopentadienyliron cations were synthesized using the divergent method. These dendrimers were decorated with chloro-, hydroxyl-, or piperazine moieties. Cyclic voltammetric studies showed that dendrimers with chloro- or hydroxyl- terminal group exhibit reversible redox activity while dendrimers with piperazine moieties showed two distinct irreversible reductive waves. Organoiron dendrimers were thermally stable with the first degradation step at 200°C associated with the decomplexation of the iron moieties. All dendrimers were evaluated against Gram-positive bacteria [Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus warneri and vancomycin-resistant Enterococcus faecium (VRE)], and showed significant activities against bacterial strains but were found to be less active in the case of chloro- terminal group. Second generation dendrimer 8 capped with piperazine exhibited inhibitory activity against Gram-positive bacteria generally comparable to that of reference vancomycin and rifampicin. Also, all dendrimers were screened against MCF-7 and HTB-26 breast cancer cell lines and dendrimer 8 exhibited significant inhibitory activity against MCF-7 compared with dendrimers in lower generations.

Transcription Factors That Defend Bacteria Against Reactive Oxygen Species.

Bacteria live in a toxic world in which their competitors excrete hydrogen peroxide or superoxide-generating redox-cycling compounds. They protect themselves by activating regulons controlled by the OxyR, PerR, and SoxR transcription factors. OxyR and PerR sense peroxide when it oxidizes key thiolate or iron moieties, respectively; they then induce overlapping sets of proteins that defend their vulnerable metalloenzymes. An additional role for OxyR in detecting electrophilic compounds is possible. In some nonenteric bacteria, SoxR appears to control the synthesis and export of redox-cycling compounds, whereas in the enteric bacteria it defends the cell against the same agents. When these compounds oxidize its iron-sulfur cluster, SoxR induces proteins that exclude, excrete, or modify them. It also induces enzymes that defend the cell against the superoxide that such compounds make. Recent work has brought new insight into the biochemistry and physiology of these responses, and comparative studies have clarified their evolutionary histories.

Electropolymerization and Impedance Spectroscopic Characterization of Thiophene Derivatives with η6-aryl-η5-cyclopentadienyliron hexaflourophosphates

Esterification reaction of organoiron complex with terminal carboxylic group with hydroxymethyl EDOT(3,4-ethylenedioxythiophene) and 2-(3-Thienyl) ethanol produced EDOT and thiophene monomers. The electrochemical polymerization of these monomers led to new polymeric materials with the conjugated system as a backbone and the iron moieties pendant to the backbone. The polymer behaved as a conductive support and the metal group acted similarly to an un-tethered complex. The modified electrode surfaces were characterized via electrochemical impedance spectroscopy to explore the capacitive properties of polymers. Further morphological characterization proved the thin film formation on the electrode surface.

Effect of gamma irradiation on chromate sorption over magnetite surface

Aqueous chromate sorption on suspended magnetite in the presence of gamma irradiation has been evaluated. Kinetics of chromate removal was evaluated using Lagergren's absorption model. Chromate removal with respect to the accumulated dose followed a Lagergren's pseudo-first-order kinetic model. A comparison of kinetics of chromate removal with respect to total accumulated dose for gamma irradiation experiment vis-à-vis with respect to time of treatment for different isothermal interactions has been undertaken. Rate constants indicate that the chromate removed per minute in isothermal equilibration at 80 °C is comparable to the chromate removed per kilogrey of gamma irradiation received. There is a redox interaction between the chromate and the ferrous of the suspended magnetite which was confirmed by X ray photo electron spectroscopy (XPS) analysis. This process reaches a saturation much before the consumption of entire ferrous ions of magnetite, indicating a passivating nature of the product. The effect of radiation on both chromate solution and dispersed magnetite to alter the redox process could be ascertained. Gaussian–Lorenzian peak fittings to the XPS data have been carried out to evaluate the chemical composition of the deposited chromium and the resultant change in the chemical composition of the iron in the oxide lattice. This indicated that the magnetite equilibrated with chromate under gamma irradiation resulted in a different surface composition as compared with the one obtained in absence of gamma irradiation. XPS data indicated the presence of hydroxyl group and oxide group attached to both iron and chromium moieties in case of irradiation, whereas only oxide group was seen with only temperature treatment.