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Lithium manganese iron phosphate (Li[Mn.sub.1-x][Fe.sub.x]P[O.sub.4], LMFP) combines the advantages of LiFeP[O.sub.4] and LiMnP[O.sub.4]. However, low electronic conductivity and sluggish lithium ion diffusion of the LMFP cathode limits its commercial application. In this work, the LMFP microspheres were co-coated by silica and N-doped carbon for the improvement of electronic and ionic conductivity of LMFP. The hydrolysis of tetraethyl orthosilicate and the polymerization of dopamine can be mutually promoted in one reaction system to realize the simultaneous precipitation of Si and C species on the LMFP surfaces without the addition of acid-base catalysts or buffering agents. After high-temperature treatment in argon, the silica and N-doped carbon co-coated LMFP microspheres were obtained with improved cycling stability (84.4% of capacity retention for 300 cycles at 1 C) and enhanced rate performance (80.0 mAh [g.sup.-1] at 5 C). Therefore, this work shows a facile and common method for the composite coating of cathode materials. Key words: silica, N-doped carbon, lithium manganese iron phosphate, cathode, lithium battery. Le phosphate de fer-manganèse lithié (Li[Mn.sub.1-x][Fe.sub.x]P[O.sub.4], LMFP) allie les avantages du LiFeP[O.sub.4] et du LiMnP[O.sub.4]. Cependant, ses applications commerciales sont limitées en raison de sa faible conductivité électronique et de la diffusion peu efficace des ions lithium issus des cathodes de LMFP. Dans le cadre des présents travaux, nous avons recouvert des microsphères de LMFP d'un composite de silice et de carbone dopé à l'azote en vue d'améliorer la conductivité électronique et ionique du LMFP. L'hydrolyse de l'orthosilicate de tétraéthyle et la polymérisation de la dopamine peuvent se catalyser mutuellement dans un système réactionnel unique, permettant la précipitation simultanée d'espèces de Si et de C sur des surfaces de LMFP sans recourir à l'ajout de catalyseurs acido-basiques ou d'agents tampons. Lorsqu'elles sont traitées à haute température sous argon, les microsphères de LMFP recouvertes d'un composite de silice et de carbone dopé à l'azote peuvent être obtenues avec une stabilité de cyclage accrue (84,4% de rétention de capacité pendant 300 cycles à 1 C) et une plus grande rapidité de chargement (80,0 mAh [g.sup.-1] à 5 C). Ces travaux ont ainsi permis de présenter une méthode simple et commune pour réaliser le revêtement de matériaux cathodiques par un composite. [Traduit par la Rédaction] Mots-clés: silice, carbone dopé à l'azote, phosphate de fer-manganèse lithié, cathode, batterie au lithium., Introduction A lot of academic research and practical applications have been carried out to develop advanced materials and manufacturing technique of lithium ion batteries, due to their advantageous electrochemical performance [...]

Fulfilment of energy in various sectors of society is the demand of today's world. Nowadays, researchers are working hard to propose such technologies to eradicate energy losses. Several improvements have been presented by the research community in this regard. After their struggle and hard work, researchers believed that this energy crisis could be overcome with the aid of fluids. So a procedure is executed to subject the fluid flows to a magnetic field. Furthermore, they also disclosed that induction of ferro-elements in a fluid under the existence of magnetic fields, known as ferrofluid, is a remarkable technique to overcome this huge social, economic, and technological problem. So the motto of the current literature is to investigate the elevated thermophysical features of viscous fluid by the inclusion of ferro-particles. To achieve said purpose, nickel zinc ferrite particles (NiZn[Fe.sub.2][O.sub.4]) are added to ethyl alcohol ([C.sub.2][H.sub.5]OH) in the presence of magnetic dipole. Flow is induced by a two-dimensional linearly elongated sheet. The governing momentum, energy, and thermal transport equations describing the thermomechanical aspects of ferrofluid is modelled in the form of partial differential expressions. Similar variables are needed to transfer the coupled partial expressions into ordinary differential system. Extensive computational interpretation of influencing parameters like ferromagnetic interaction parameter, viscous dissipation, and Curie temperature parameter on associated profiles is accomplished using the shooting method in collaboration with the Runge-Kutta-Fehlberg method. It is found that the primary function of the magnetic dipole is to reduce the velocity within the boundary layer and it tends to enrich the thermal attitude. Diminishing of the momentum distribution of ferro-particles is established in the presence of a magnetic dipole. Inclusion of mixed convection decreases the momentum, whereas an increase is induced in the thermal profile. Decrease of convective heat transfer magnitude is observed in the presence of magnetic dipole. Key words: magnetic dipole, ferrofluid, mixed convection, shooting method, wall shear stresses, heat fluxes, nickel zinc ferrites. Le monde d'aujourd'hui demande soient satisfaits que les besoins en energie des divers secteurs de la societe. A cet effet, les chercheurs s'activent pour proposer les technologies susceptibles d'eliminer les pertes en energie. Plusieurs propositions ont ete avancees par les chercheurs dans ce but. Apres beaucoup d'efforts, ils croient que ce probleme en energie peut etre eradique a l'aide de fluides. La procedure implique un flot de fluide interagissant avec un champ magnetique. Il est propose que l'introduction de materiel ferreux dans un fluide sous champ magnetique, formant un ferrofluide (une technologie remarquable), sera susceptible de contribuer a reduire ce grave probleme, a la fois social, economique et technologique. La tendance dans la litterature favorise l'examen des caracteristiques thermophysiques de fluides visqueux porteurs de particules ferreuses. Dans cette etude, nous considerons des particules de ferrite de zinc (NiZn[Fe.sub.2][O.sub.3]) dans de l'alcool ethylique ([C.sub.2][H.sub.5]OH) en presence d'un champ magnetique. Le flot est controle par deux plaques 2D allongees. Les equations directrices pour l'impulsion, l'energie et le transfert de chaleur decrivant les caracteristiques thermophysiques du ferrofluide, sont materialisees sous la forme d'equations differentielles. Des variables similaires servent a transformer ces equations aux derivees partielles couplees en un systeme d'equations differentielles ordinaires. Les methodes de Runge-Kutta-Fehlberg et de tir, nous permettent des solutions extensives numeriques de ces equations qui decrivent les effets sur les profils associes dus aux parametres pertinents, comme le parametre d'interaction ferromagnetique, la dissipation visqueuse et la temperature de Curie. La premiere consequence observee est que le champ magnetique reduit la vitesse dans la couche limite, ce qui augmente les transferts thermiques. Le champ magnetique diminue la distribution en impulsion des particules ferreuses. L'apparition de convexion mixte cause une diminution de l'impulsion et une augmentation du profil thermique, alors que le champ magnetique diminue le transfert convectif de chaleur. [Traduit par la Redaction] Mots-cles: dipole magnetique, ferrofluide, convexion mixte, methode de tir, contrainte de cisaillement mural., 1. Introduction Ferrofluids are smart nanomaterials synthesized by introducing ferromagnetic particles into a base fluid. Ferrofluids are a colloidal mixture of liquid and nanoscale ferromagnetic particles suspended uniformly in a [...]

An Erratum to this paper has been published: https://doi.org/10.1134/S1061934822340019, Author(s): Khadijeh Eskandari [sup.1], Hajar Zarei [sup.2] [sup.3], Hedayatollah Ghourchian [sup.4], Seyed-Mostafa Amoozadeh [sup.5] Author Affiliations: (1) grid.411521.2, 0000 0000 9975 294X, Nanobiotechnology Research Center, Baqiyatallah University of Medical Science, [...]

A chemical kinetic model is presented for the formation and accumulation of secondary ferrimagnetic minerals (SFMs) in soil constructed using experimentally determined rate constants and validated against field data. The primary objective is to critically assess the significance of competing causal mechanisms and disputed environmental controls under temperate conditions. Four findings are important in relation to current application of soil magnetic susceptibility data. First, transformation of hydrous ferric oxide to magnetite should dominate SFM formation, controlled primarily by parent material ferrous silicate concentration and climate. Second, abiotic reactions should account for most of the SFM production; the most significant impact of high [Fe.sup.2+] concentrations created by dissimilatory iron-reducing bacteria is enhanced export of iron from the soil in runoff. Third, the model predicts a correlation between hematite and magnetite concentrations, weakening field support for direct transformation of hydrous ferric oxide to maghemite. Fourth, magnetic susceptibility enhancement should increase strongly with weathering duration. doi: 10.1130/G31514.1

Iron oxide (FeO) is an important component in the mineralogy of Earth's lower mantle and possibly its core, so its phase diagram is essential to models of the planet's interior. The melting curve of wustite, [Fe.sub.0.94]O, was determined up to 77 GPa and 3100 K in a laser-heated diamond anvil cell. Melting transition temperatures were identified from discontinuities in the emissivity vs. temperature relationship within the laser-heated spot. The melting curve exhibits no obvious kinks that could be related to a subsolidus transition in wustite, but there is evidence for a two-phase loop at pressures below 30 GPa. Comparison of these results to previous studies on Fe, Fe-O, and Fe-S confirms that the melting point depression in the Fe-O system remains significantly less, by a factor of 2 or more, than that in the Fe-S system up to pressures exceeding 80 GPa. Keywords: High pressure, wustite, phase equilibria, multispectral imaging radiometry DOI: 10.2138/am.2010.3463

This study demonstrates a new and relatively general route to the development of multiwalled carbon nanotube (MWNT)-based integrative electrochemical biosensors by confining ferricyanide redox mediator onto MWNTs. The ferricyanide-confined MWNTs are synthesized first through grafting of epoxy chloropropane onto MWNTs with in situ cationic ring-opening polymerization and then introducing the positively charged methylimidazolium moieties into the grafted polymer with a quaternization reaction. The grafted polymers with positively charged methylimidazolium moieties tethered onto MWNTs can essentially be used to confine redox-active ferricyanide onto MWNTs to form a redox mediator-confined nanocomposite with a good stability and excellent electrochemical property. The synthetic nanocomposite with surface-confined ferricyanide is demonstrated to be well-competent as the efficient electronic transducers for the general development of electrochemical biosensors upon combination with biorecognition units, which is illustrated by using glucose oxidase and laccase as two model biorecognition units. This study essentially paves a facile and general approach to the development of integrative nanostructured electrochemical biosensors.

The studies have shown that in both native and reconstituted [4Fe-4S] FNR, the reaction environment and the presence of [Fe.sup.2} and [Fe.sup.3} chelators have influenced the cluster conversion reactions. The sensitivity of FNR cluster conversion kinetics to chelators has disclosed mechanism by which the cell can fine-tune its response to the onset of aerobic conditions.

The effects of 10 paramagnetic metal complexes on [F.sup.-] ion [super 19]F NMR transverse relaxation rates are studied in aqueous solutions as a function of temperature. The results have shown that [F.sup.-] [super 19]F NMR relaxation is used for predicting the reactivities of other [Fe.sup.III] complexes toward reduction by [O.sub.2.sup.-], which is a key step in the biological production of reactive oxygen species.

The synthesis and characterization of ordered mesoporous two-line ferrihydrite are described. The results are described by assuming a spin-glass-like state of the surface spins and the two-dimensional hexagonal two-line ferrihydrite has shown very large coercivity.

The iron(III) complexes of 1,4,8,11-tetraaza[14]annulenes are prepared as catalase mimics. A non-oxygen releasing pathway of hydrogen peroxide decomposition is disclosed besides oxygen production.

The crystal structure, thermal studies and magnetic properties of [Fe[(bpp).sub.2]][[Cr(L)[(ox).sub.2]].sub.2].n[H.sub.2]O complexes are described. The effect of lattice solvent in the magnetic properties of these spin-crossover complexes is examined by a combined structural, calorimetric and magnetic study.

Ab initio calculations are used for studying the origin of the spin-transition behavior of the Prussian blue analogue cesium iron hexacyanochromate CsFe[Cr[(CN).sub.6]]. The studies have shown that the spin-transition phenomenon in the Prussian blue analogue CsFe[Cr[(CN).sub.6]] compound is driven by charge reorganization within the matrix.

The rates of proton transfer to synthetic Fe-S-based clusters with a binuclear core composition [{MeFe[S.sub.2]}.sup.n} (M = Fe, Mo or W) containing [[mu].sub.2]-S are analyzed. The results have helped in examining the affects of metal composition, terminal ligands and nuclearity on the rates of proton transfer.

X-ray diffraction experiments in pulsed magnetic fields are used for studying the giant magnetic-field-induced strain in the martensitic phase of ordered [Fe.sub.3]Pt alloy. The results have shown that the magnetic-field-induced strain associated with the rearrangement of the variants has occurred in a very fast sweeping pulsed field.

The synthesis of a family of iron(II) spin crossover monomers containing the bis-meridional ligands 2-(1-pyridin-2-ylmethyl-1H-pyrazol-3-yl)-pyrazine (picpzpz) and 2-(3-(2-pyridyl)pyrazol-1-ylmethyl)pyridine) (picpypz) is described.

The core extends from the depth of 2,900 km to the center of the Earth and is composed mainly of an iron-rich alloy with nickel, with 10% of the mass comprised of lighter elements like hydrogen, but the exact composition is uncertain. We present a quantum mechanical first-principles study of the dynamical stability of Feh phases and their phonon densities of states at high pressure. Our free-energy calculations reveal a phonondriven stabilization of dhcp Feh at low pressures, thus resolving the present contradiction between experimental observations and theoretical predictions. Calculations reveal a complex phase diagram for Fell under pressure with a dhcp [right arrow] hcp [right arrow] fcc sequence of structural transitions. high pressure | iron hydride | phonons and phase transition | solid Earth | sound velocity

Phototrophic Fe(II)-oxidizing bacteria couple the oxidation of ferrous iron [Fe(II)] to reductive C[O.sub.2] fixation by using light energy, but until recently, little has been understood about the molecular basis for this process. Here we report the discovery, with Rhodopseudomonas palustris TIE-1 as a model organism, of a three-gene operon, designated the pio operon (for phototrophic iron oxidation), that is necessary for phototrophic Fe(II) oxidation. The first gene in the operon, pioA, encodes a c-type cytochrome that is upregulated under Fe(II)grown conditions. PioA contains a signal sequence and shares homology with MtrA, a decaheme c-type cytochrome from Shewanella oneidensis MR-1. The second gene, pioB, encodes a putative outer membrane beta-barrel protein. PioB is a homologue of MtrB from S. oneidensis MR-1. The third gene, pioC, encodes a putative high potential iron sulfur protein (HiPIP) with a twin-arginine translocation (Tat) signal sequence and is similar to the putative Fe(II) oxidorednctase (Iro) from Acidithiobacillus ferrooxidans. Like PioA, PioB and PioC appear to be secreted proteins. Deletion of the pio operon results in loss of Fe(II) oxidation activity and growth on Fe(II). Complementation studies confirm that the phenotype of this mutant is due to loss of the pio genes. Deletion of pioA alone results in loss of almost all Fe(II) oxidation activity; however, deletion of either pioB or pioC alone results in only partial loss of Fe(II) oxidation activity. Together, these results suggest that proteins encoded by the pio operon are essential and specific for phototrophic Fe(II) oxidation in R. palustris TIE-1.

This paper provides a detailed documentation of microstructures developed in the banded iron formation (BIF) of Gua mine, located in the Bonai Synclinorium (eastern India), where the rocks have been subjected to three deformations ([D.sub.1] to [D.sub.3]). Folded iron ores, quartz strain fringes around rigid core objects and folded iron ore layers, and refracted quartz veins are described from samples taken from [D.sub.2] folds in the banded iron formation. Orientations of microstructures are compared with mesoscopic structures to interpret the generations of ore minerals, planar structures and the time relationship between deformation and development of different microstructures. The mechanism of [D.sub.2] folding is worked out and its bearing on microstructure development is discussed. The [D.sub.2] folds are inferred to have developed by a combination of tangential longitudinal strain in the competent layer, flexural flow in the incompetent layers and flexural slip at the interface between layers of differing competence. Homogeneous flattening strain superposed the earlier strain, which led to modification of the folds in the competent layer from class 1B to 1C. This strain is quantified and is found to be higher in the limb than the hinge of a fold. Diffusive mass transfer by solution and bulging dynamic recrystallization in quartz are inferred as the dominant deformation processes during folding. Moreover, based on comparison with published deformation microstructure maps, the microstructures of the present study are estimated to have developed between 300 and 350 [degrees]C temperatures at a strain rate of [10.sup.-14]-[10.sup.-12][s.sup.-1] which are geologically realistic conditions for naturally deformed rocks. Keywords: microstructure, banded iron formations, quartz, pressure solution, recrystallization, strain, folding.

We present the iron isotope composition of primary, diagenetic and metamorphic minerals in five samples from the contact metamorphosed Biwabik Iron Formation. These samples attained peak metamorphic temperatures of l[per thousand] on the millimeter scale. Minerals in the lowest grade samples consistently show a sequence in which [delta][sup.56]Fe of magnetite > silicate [greater than or equal to] carbonate. The intermineral Fe isotope differences vary in a fashion that cannot be reconciled with theoretical temperature-dependent fractionation factors. Textural evidence reveals that most, if not all, magnetite in the Biwabik Formation is diagenetic, not primary, and that there was tremendous element mobility during diagenesis. The short duration of contact metamorphism allowed diagenetic magnetite compositions to be preserved throughout prograde metamorphism until at least the appearance of olivine. Magnetite compositions therefore act as an isotope record of the environment in which these sediments formed. Larger-scale fluid flow and longer timescales may allow equilibration of Fe isotopes in regionally metamorphosed rocks to lower temperatures than in contact metamorphic environments, but weakly regionally metamorphosed rocks may preserve small-scale Fe isotopic heterogeneities like those observed in the Biwabik Iron Formation. Importantly, Fe isotope compositions that are characteristic of chemical sedimentation or hydrothermal processes are preserved at low grade in the form of large inter-mineral variations, and at high grade in the form of unique bulk rock compositions. This observation confirms earlier work that has suggested that Fe isotopes can be used to identify sedimentary processes in the Precambrian rock record.

Our whole-genome microarray studies of Neisseria meningitidis MC58 previously identified a set of 153 genes whose transcription was activated during growth in iron. In this study, Fur-mediated regulation of the iron-activated nspA gene was confirmed, whereas iron-activated regulation of the secY gene was demonstrated to be Fur independent. Analysis of the Fur binding sequences in the nspA gene and an additional iron-activated and Fur-regulated gene identified a hexameric (G/T)ATAAT unit in the operator regions of these genes similar to that observed in Fur- and iron-repressed genes. These studies indicate that the expression of the iron-activated nspA and secY genes in N. meningitidis occur by Fur-dependent and -independent mechanisms, respectively.

In-situ X-ray absorption spectroscopy at the Fe K-edge was used to characterize the local structural environment of [Fe.sup.2+] and [Fe.sup.3+] in silicate melts at high temperature (up to 1050 [degrees]C) in comparison to their quenched glassy analog at room temperature. Measurements were performed on binary alkali-silicate compositions and on haplogranitic compositions, which were doped with about 5 wt% [Fe.sub.2][O.sub.3]. Changes in the structural environment of Fe were evaluated by analyzing both the pre-edge feature and the first maximum of the EXAFS of the spectra. In most cases, the spectra collected at high temperature differed from those of the quenched samples. At reducing conditions, the melts showed slightly higher amounts of low-coordinated [Fe.sup.2+] than their glassy counterparts. This finding is consistent with results of earlier studies (e.g., Jackson et al. 1993), but the observed change in speciation is smaller than reported by these authors. At oxidizing conditions, glasses and melts displayed a more heterogeneous behavior. The spectra of alkali-silicate compositions indicate higher amounts of low-coordinated [Fe.sup.3+] in the melt, whereas no significant difference between melt and glass was observed for [Fe.sup.3+] in haplogranitic compositions, even if the latter are peralkaline. The amount of non-bridging O atoms in the glass/melt system appears to play an important role particularly for [Fe.sup.3+]. However, more complex relationships between Fe and other structural components, especially Al, are possible. Keywords: XAS (XAFS, XANES), Fe K-edge, high-temperature studies, Fe in silicate melts, melt properties, glass properties

Geobacter species are key members of the microbial community in many subsurface environments in which dissimilatory metal reduction is an important process. The genome of Geobacter sulfurreducens contains a gene designated [rel.sub.Gsu], which encodes a RelA homolog predicted to catalyze both the synthesis and the degradation of guanosine 3',5'-bispyrophosphate (ppGpp), a regulatory molecule that signals slow growth in response to nutrient limitation in bacteria. To evaluate the physiological role of [Rel.sub.Gsu], in G. sulfurreducens, a [rel.sub.Gsu] mutant was constructed and characterized, and ppGpp levels were monitored under various conditions in both the wild-type and [rel.sub.Gsu] mutant strains. In the wild-type strain, ppGpp and ppGp were produced in response to acetate and nitrogen deprivation, whereas exposure to oxygen resulted in an accumulation of ppGpp alone. Neither ppGpp nor ppGp could be detected in the [rel.sub.Gsu] mutant. The [rel.sub.Gsu] mutant consistently grew to a higher cell density than the wild type in acetate-fumarate medium and was less tolerant of oxidative stress than the wild type. The capacity for Fe(III) reduction was substantially diminished in the mutant. Microarray and quantitative reverse transcription-PCR analyses indicated that during stationary-phase growth, protein synthesis genes were up-regulated in the [rel.sub.Gsu] mutant and genes involved in stress responses and electron transport, including several implicated in Fe(III) reduction, were down-regulated in the mutant. The results are consistent with a role for [Rel.sub.Gsu] in regulating growth, stress responses, and Fe(III) reduction in G. sulfurreducens under conditions likely to be prevalent in subsurface environments.