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Cellulose-supported on Pd nanoparticles (Pd/cellulose) were successfully prepared by chemical reduction technique and characterized by various experimental tools. The Pd/cellulose catalyst was found to effectively promote the oxidation of glucose into gluconic acid under mild conditions. The base played a crucial role in the oxidation of glucose into gluconic acid. Glucose was fully converted at room temperature after 3 h by the use of stoichiometric amount of Na2CO3 to neutralize gluconic acid, and gluconic acid was obtained in a high yield of 91.2%. The catalyst was recovered from product and reused up to five times without significant loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

Nanocomposites based on TiO2 nanotube arrays (TiO2-NTA) have received increasing attention for photoconversion and photocatalytic reactions. Here, TiO2-NTA were prepared by an anodic oxidation process. ZnO and ZnCr2O4 nanoparticles were further anchored on the surface of the pre-synthesized TiO2-NTA to form a ternary ZnO/ZnCr2O4@TiO2-NTA (Zn-Cr-O@TiO2-NTA) nanocomposite by an electrochemical reduction-oxidation strategy. Compared to bare TiO2-NTA, the Zn-Cr-O@TiO2-NTA nanocomposite shows remarkably higher photovoltaic conversion efficiency (nine times greater) under visible light irradiation, and photocatalytic H2 evolution activity (2.8 times greater) under simulated sunlight irradiation, respectively. The construction of ternary nanocomposite is beneficial to enhancing the absorption of simulated sunlight irradiation. Moreover, the Type-II semiconductor heterojunction facilitates separation of electron-hole pairs and interfacial charge transport. As a result, improvement of photoconversion efficiency has been obtained. This work may have fundamental importance to designing complex and efficient photoelectrodes for energy-harvesting applications, including photovoltaic solar cells and water splitting. [ABSTRACT FROM AUTHOR]

Highly-dispersed copper nanoparticles (Cu NPs) were fabricated on the surface of reduced graphene oxide via direct hydrazine hydrate reduction of Cu2+ in aqueous solution. Scanning electron microscope and transmission electron microscope images show that the Cu NPs are distributed on the surface of graphene nanosheets, and the average particle size was about 40 nm. The Cu NPs supported on graphene have high reaction activity for the oxidation of toluene to corresponding benzaldehyde. It was found that the selectivity reached 66.5% and the conversion of toluene reached 11.5%. [ABSTRACT FROM AUTHOR]

Impregnation catalysts based on CuO, MnOx, and CuO-MnOx with different Cu/Mn ratios supported on ceramic monoliths of alumina and silica are studied by BET, mercury porosimetry, X-ray diffraction analysis, transmission and scanning electron microscopy, temperature-programmed reduction with H2, diffuse reflectance electron spectroscopy, and differential dissolution. It is found that, in the butane oxidation reaction, CuO-MnOx catalysts exert a synergistic effect, which is attributed to the formation of highly defective phases of complex oxides of the nonstoichiometric spinel type with a large number of interparticle boundaries in the near-surface layers of the support. [ABSTRACT FROM AUTHOR]

New materials based on electric arc furnace (EAF) dust have been produced via temperature-programmed reduction using hydrogen gas at different temperatures. Scanning electron microscopy, thermal analysis, X-ray diffraction, and Mössbauer spectroscopy suggested that the EAF dust is reduced by hydrogen at 600 and 700 °C producing reduced iron, e.g., iron (II) and iron metallic, magnetics and more active catalytic phases. The new materials show magnetic behavior as well as EAF starting material. Electron paramagnetic resonance studies using N-t-butyl-α-phenylnitrone as a trapped radical agent were performed showing characteristic signals related to paramagnetic species produced exclusively by the interaction of catalysts with hydrogen peroxide (H2O2). The new magnetic materials were successfully used for pollutant removal by adsorption followed by oxidation of model dyes such as methylene blue and indigo carmine. In addition, the great advantage of these materials is that they may be easily recovered magnetically and reused. [ABSTRACT FROM AUTHOR]

Surface-fluorinated TiO materials with high {001} facet exposure were prepared by a simple and high-yield preparation procedure. Faceted/fluorinated samples showed a high photocatalytic performance not only in oxidation processes, tested in phenol and methyl orange degradation, but also in a reduction process as Cr(VI) photoreduction. Reaction rates for these materials greatly exceeded the ones obtained for materials prepared without fluorine addition and for commercial TiO Degussa (Evonik) P25 used as reference photocatalyst. A broad characterisation of the samples allowed us to estimate the percentages of different facets and the amount and form in which the fluorine is found on the surfaces. Good photocatalytic behaviour can be ascribed to both high {001} facet exposure and adsorbed fluorine on the photocatalysts surfaces. [ABSTRACT FROM AUTHOR]

The correlation between the CO reactivity and pore structure of carbon anodes was experimentally investigated. The pore structures of the anodes before and after CO oxidation were characterized using image analysis. The porosity, mean pore diameter, and the number of micro-cracks decreased with increasing anode forming pressure, while they increased with over-compaction. With prolonged CO oxidation time, the porosity, pore density, mean pore diameter, pore aspect ratio, and the number of micro-cracks increased due to the merging of small pores, increased pore connectivity, and generation of new pores. The activation energy decreased with increasing porosity of the anodes' pitch phase due to easier CO penetration and reaction within the anodes. The results confirm that the fine pitch-coke phase of anodes is preferentially consumed, a cause of carbon dusting. Optimization of the pore structures to balance the pitch, coke, and butt phases may potentially further reduce carbon dusting. [ABSTRACT FROM AUTHOR]

Cyclic reduction and oxidation (redox) of solid oxide fuel cell (SOFC) anodes generally leads to cell degradation and reduces the cell lifetime. The investigation of the sequential cyclic redox of nickel/scandia-stabilized-zirconia (Ni/ScSZ) SOFC anode films presented in this study is aimed at understanding the properties of screen-printed Ni/ScSZ anode films fabricated using a rheologically optimized ink under redox condition. An optimized NiO/ScSZ screen-printing ink containing 28 vol% of solids and 2 wt% binder was chosen for the fabrication of the anode films. The mechanical properties, DC conductivity and electrochemical performance of Ni/ScSZ films were measured between 0 and 15 cycles and related to the microstructural change of the anode. All these properties degraded with increasing redox cycles. The mechanical hardness of re-oxidized anode decreases from 8753 to 1314 MPa, while the DC conductivity of re-reduced anode decreases from 1400 to 410 S/cm at 800 °C. Also, the anode polarization resistance increases from 0.75 to 2.7 Ωcm at 800 °C. This degradation is related to the separation of Ni particles, which reduces the density and Ni-Ni particle connectivity. The decrease in electrochemical performance can be related to a decrease in the anode triple-phase boundary density in the fabricated films. However, all the printed films remain stable with acceptable electrical and electrochemical performance without any cracks or delamination even after 15 cycles. This indicates that ink optimization through rheological testing is an important way to prevent crack formation in printed anode films that results from redox processes in real SOFC operating conditions. [ABSTRACT FROM AUTHOR]

The oxidation behaviors of South Africa (SA) titanomagnetite (TTM) and its effects on the gas solid reduction in the fluidized bed were investigated on the basis of the two-stage short process of direct reduction-electric arc furnace (DR-EAF) melting separation. The results showed that the oxidation phase transformations in the high-temperature range from 1073 K to 1223 K (800 °C to 950 °C) can be divided into two typical processes: with the fast generation of pseudobrookite and with the maghemite generation at the initial stage. The reduction efficiency for SA TTM was improved by the preoxidation treatment, mainly because of the dissociation of titania-ferrous oxides to the easy reducible hematite. However, at a preoxidation temperature higher than 1173 K (900 °C), the improving effect became weak, due to high-temperature sintering and the larger crystallite size of oxidation products. There is an extreme value of the preoxidation influence, and the optimum preoxidation time is different for various temperatures. The reduction metallization degree of SA TTM can be relatively improved by 14.5 and 4.5 pct for the first and second reduction steps, respectively, by 1173 K (900 °C) preoxidation with an optimum time of 30 minutes. Finally, the equilibrium relationship between the metallization degree and the gas reduction potential for TTM ore with preoxidation treatment was built. [ABSTRACT FROM AUTHOR]

Controlled synthesis of bimetallic catalysts has attracted much attention in heterogeneous catalysis because their catalytic activity depends on the size of nanoparticles and hence the methods of synthesis. In this work, one convenient method was proposed, with an aim to control the size and dispersion of bimetallic nanoparticles. In this method, Cu (or Ni) configurational ion of hydrotalcites was used as directing reagent, which directed the position and dispersion of the final bimetallic nanoparticles by employing the metal interaction between Cu and Au as the driving force. The size, structure and composition of bimetallic nanoparticles were characterized using techniques of X-ray diffraction (XRD), nitrogen physisorption, X-ray photoelectron spectra (XPS) and scanning transmission electron microscopy (STEM). The mean size of bimetallic AuCu nanoparticles was 2.5 nm, which was 1/4 (Step-impregnation) or 1/10 (Co-impregnation) of that prepared by traditional methods. Even if the loading of Au was increased to 10 wt%, the obtained AuCu nanoparticles were still well dispersed. The catalytic activity of AuCu and AuNi nanoparticles in aerobic oxidation of benzyl alcohol was far higher than those prepared by traditional methods. The mechanism of forming bimetallic nanoparticles was investigated. It was found that the dispersion of Cu (or Ni) and the interaction between Cu (or Ni) and Au are two key factors affecting the dispersion of AuCu (or AuNi) nanoparticles. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Monodispersed palladium nanoparticles (PdNp) have been synthesized by a green rapid bio-reduction method under room temperature and pressure. The reducing agents mainly involved in these processes are the various water soluble plant metabolites, polyphenols as well as co-enzymes present in the leaf extract of Tulsi ( Ocimum sanctum). An active and stable montmorillonite K-10 supported heterogeneous catalyst was prepared using these PdNp for oxidation of alcohols to their corresponding carbonyl compounds with efficient yield and having good reusability. These are characterized by TEM, XRD, BET surface area and UV-Vis absorption spectroscopy. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The O/Ru(0001) system is widely studied due to its rich phase variety of various stoichiometry and atomic arrangements, including the formation of a RuO/Ru(0001) oxide layer. Apart from homogeneous ruthenium surfaces in certain oxidation states, also strongly heterogeneous surfaces can exist due to oxidation state's variation at the nanoscale. We report on a scanning tunneling microscopy (STM) study of the nanostructuring of the oxidized Ru(0001) surface as a result of its interaction with molecular oxygen at elevated temperatures and subsequent reduction of a resulting RuO film by CO or HCl molecules from the gas phase in high-vacuum environment. [ABSTRACT FROM AUTHOR]

Cobalt oxide nanoparticles were functionalized with sodium citrate and coated with a silica shell (CoO@Q@SiO). Different experimental configurations were tested in order to obtain low-sized cobalt oxide nanoparticles with high crystallinity, using the chemical reduction-oxidation method. Then, the nanoparticles were coated with silica using the Stöber method, obtaining a silica cover on top of the cobalt oxide nanoparticle surface with a few nanometers thickness. This method permits the functionalization of the nanoparticles at the time of coating. Results show that with a heat treatment of 500 C, high-crystallinity cobalt oxide nanoparticles are obtained with a spherical shape and an average diameter of 30 nm, whereas the silica cover has 5 nm thickness. Evidence of nanoparticle functionalization was obtained through the measurement of the absorption bands of the functional groups of the sodium citrate with a silica cover. In addition, coated nanoparticles show a reduction of their magnetic remanence as well as their coercivity with respect to the uncoated nanoparticles since silica acts as barrier avoiding superficial contact between magnetic nanoparticles. [ABSTRACT FROM AUTHOR]

The influence of pressure on the oxidative cracking of light alkanes C-C was investigated. An elevated pressure reduces the temperature of oxycracking of light alkanes but with further increase in pressure the effect is reduced. The applied pressure decreases the temperature of the total conversion of oxygen while the maximum conversion of alkanes is not influenced. The pressure above atmospheric promotes oxidative cracking reactions but weakly affects thermal processes. At deep conversion of light alkanes, the selectivity towards main products is nearly invariable at the utilized pressures. [ABSTRACT FROM AUTHOR]

Although the chemical reduction and advanced oxidation processes have been widely used individually, very few studies have assessed the combined reduction/oxidation approach for soil remediation. In the present study, experiments were performed in spiked sand and historically contaminated soil by using four synthetic nanoparticles (Fe, Fe/Ni, FeO, FeNiO). These nanoparticles were tested firstly for reductive transformation of polychlorinated biphenyls (PCBs) and then employed as catalysts to promote chemical oxidation reactions (HO or persulfate). Obtained results indicated that bimetallic nanoparticles Fe/Ni showed the highest efficiency in reduction of PCB28 and PCB118 in spiked sand (97 and 79 %, respectively), whereas magnetite (FeO) exhibited a high catalytic stability during the combined reduction/oxidation approach. In chemical oxidation, persulfate showed higher PCB degradation extent than hydrogen peroxide. As expected, the degradation efficiency was found to be limited in historically contaminated soil, where only Fe and Fe/Ni particles exhibited reductive capability towards PCBs (13 and 18 %). In oxidation step, the highest degradation extents were obtained in presence of Fe and Fe/Ni (18-19 %). The increase in particle and oxidant doses improved the efficiency of treatment, but overall degradation extents did not exceed 30 %, suggesting that only a small part of PCBs in soil was available for reaction with catalyst and/or oxidant. The use of organic solvent or cyclodextrin to improve the PCB availability in soil did not enhance degradation efficiency, underscoring the strong impact of soil matrix. Moreover, a better PCB degradation was observed in sand spiked with extractable organic matter separated from contaminated soil. In contrast to fractions with higher particle size (250-500 and <500 μm), no PCB degradation was observed in the finest fraction (≤250 μm) having higher organic matter content. These findings may have important practical implications to promote successively reduction and oxidation reactions in soils and understand the impact of soil properties on remediation performance. [ABSTRACT FROM AUTHOR]

The mechanism of CO oxidation on copper oxide catalysts without additives and with cerium and platinum additives supported on γ-AlO was studied. It was found that the presence of Ce and Pt facilitated the reduction of copper and increased the activity of the catalysts. It was established that the parent substances participated in the reaction from an adsorbed state; in this case, the surface coverage of all of the catalysts with oxygen was greater than the coverage with CO, and the reaction system components exhibited different adsorption capacity. The introduction of Ce increases the bond strength of CO with the surface and weakens the bond of oxygen with the surface. The presence of Pt increases the bond strengths of CO, O, and CO with the surface. [ABSTRACT FROM AUTHOR]

Mo-Si-B-alloys are promising materials for high-temperature applications because of their high melting point, excellent phase stability, large alloying capabilities, and reasonable mechanical as well as oxidative properties. A continuing alloy development is, however, required because of the catastrophic oxidation taking place at intermediate temperatures and the rather high density. The addition of Ti stabilizes a new ternary phase field including the MoSi (T1) phase instead of the MoSi (A15) phase. Alloys comprising the phases Mo, T1 and MoSiB (T2) show very high creep resistance, improved oxidation behavior and significantly reduced density. The new T1 phase seems to play a crucial role in the improved oxidation resistance of these new materials, since this phase exhibits excellent oxidation behavior at intermediate and high temperatures. The 4-component alloys possess superior creep behavior compared to Mo-Si-B alloys with the same microstructural phase arrangement and size or to the single crystal Ni-base superalloy CMSX-4. The main reason was found to be the formation of Ti-rich silicide precipitates during processing. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the activity and functionality of laccase incorporated into laboratory-coated surface-sized paper. The effects of the physicochemical properties of the studied sized paper grades (permeability, porosity, and wetting) on the enzyme activity were studied. The enzymatic activity of laccase was measured either by following the oxidation of the substrate (mediator) with spectrophotometry or by monitoring the reduction of oxygen by luminescence quenching. The results showed that the initial activity of laccase incorporated into the coating did not decrease during the first 4 weeks and the activity was partly preserved even after 6 months. The functionality of the enzyme in sized papers was examined using 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as the substrate. ABTS was inkjet-printed on the sized paper, and the reaction between laccase and ABTS appeared as a color change. The most important factor affecting the color response was the enzyme activity. Other beneficial factors affecting the color response were the hygroscopic nature and wettability of the sized paper. The results showed that the fabrication of bioactive paper is possible with a relatively simple strategy, i.e., by incorporation of the biomolecules in the coating formulation (paste). No major investments would be needed to start the production of this kind of environmentally sustainable, low-cost, and lightweight paper-based bio-indicator, e.g., for authentication applications. [ABSTRACT FROM AUTHOR]

Cinnamylacetamides reacted with arylsulfenyl chlorides in chloroform in the absence of LiClO affording 5-(arylsulfanyl)-6-phenylpiperidin-2-ones. Their reduction with a system LiAlH-AlCl resulted in 3-(tolylsulfanyl)-1,2-diphenylpiperidine, and with Raney nickel, in 1-aryl-6-phenylpiperidin-2-ones. The latter treated with LiAlH-AlCl were converted into 1-aryl-2-phenyl-piperidines. The oxidation of 5-(arylsulfanyl)-6-phenylpiperidin-2-ones with hydrogen peroxide in acetone led to the formation of 5-sulfinyl-, and with oxone, to 5-sulfonyl derivatives. [ABSTRACT FROM AUTHOR]

Iron-sulphur (Fe-S) clusters are inorganic cofactors that are found in nearly all species and are composed of various combinations of iron and sulphur atoms. Fe-S clusters can accept or donate single electrons to carry out oxidation and reduction reactions and to facilitate electron transport. Many details of how these complex modular structures are assembled and ligated to cellular proteins in the mitochondrial, nuclear and cytosolic compartments of mammalian cells remain unclear. Recent evidence indicates that a Leu-Tyr-Arg (LYR) tripeptide motif found in some Fe-S recipient proteins may facilitate the direct and shielded transfer of Fe-S clusters from a scaffold to client proteins. Fe-S clusters are probably an unrecognized and elusive cofactor of many known proteins. [ABSTRACT FROM AUTHOR]

The direct oxidation of stibnite (SbS) using a gas mixture of nitrogen-oxygen was investigated in a pilot plant. Steady-state pilot operation of 5 and 10 t/d was normally observed during the pilot test of 100 days, and a cleaning experiment of high-antimony molten slag from oxygen-enriched bottom-blown was tested by direct reduction in a laboratory-scale electric furnace. Autogenous smelting was achieved without adding any other fuel, which guaranteed the feasibility and advantage of oxygen-enriched bottom-blown stibnite. Through analysis and calculation, the sulfur dioxide concentration in offgas was more than 8 pct, which meets the requirement for the preparation of sulfuric acid. In the reduction experiment, the effects of added CaO, the ratio of coal ( ω = actual weight of coal/theoretical weight of coal), and the slag type on the reduction procedure were considered. The residual slag obtained after reduction averaged less than 1 g/ton Au and less than 1 wt pct Sb. The metal phase contained iron less than 3 wt pct, and the recoveries of Au in the metal phase were more than 98 pct. This process shows significant environmental and economic benefits compared with previous processes. [ABSTRACT FROM AUTHOR]

The influence of reducing and oxidizing buckwheat sourdoughs on the rheological, protein, and bread properties of buckwheat and brown rice flour was investigated. Batters and breads prepared with chemically acidified doughs, fresh pre-doughs, and fresh pre-doughs containing glutathione (3 mM) were used as controls. No significant differences were observed after the addition of reducing and oxidizing sourdoughs in all trials. Proteolysis was observed after proofing time in buckwheat and brown rice batters, respectively. Acidified doughs increased the elasticity and the gelatinization temperature of buckwheat batters. No notable microstructure changes were detected in brown rice batters. The extension of fermentation time in sourdough caused a slight decrease in bread volumes in all trials. Sourdoughs increased the bread volume and decreased the crumb hardness of buckwheat breads. In trials with brown rice flour, the addition of sourdough did not show relevant volume differences as compared to the controls, except big voids in sourdough bread crumb. Linear correlations between hardness, volume, and cells' density were observed. However, no clear correlations among rheological parameters and bread characteristics could be detected. These results indicated that the applied strains were responsible for the leavening capacity of the yeast during the proofing time and for crumb structure in trials with buckwheat and brown rice flour. Applied sourdoughs were able to change the molecular, and bread properties of buckwheat and brown rice bread. [ABSTRACT FROM AUTHOR]

A series of highly active Pt-TiO catalysts have been prepared by impregnation methods via different reduction processes and used for catalytic decomposition of benzene. The oxidized and reduced Pt-TiO catalysts exhibit apparent differences in physical/chemical features (e.g. particle size, chemical state, and electronic property of Pt nanoparticles, and surface oxygen) and catalytic activities for benzene oxidation. Nearly 100 % benzene conversion is achieved on Pt-TiO catalysts obtained by the sodium citrate (CHNaO·2HO, NaCt) reduction at approximate 160 °C. Metallic Pt nanoparticles have strong capacity for oxygen activation, and the negative charges and rich chemisorbed oxygen on the surface of metallic Pt nanoparticles are probably responsible for their high catalytic activities for benzene oxidation. Graphical Abstract: 1 wt% Pt-TiO2 catalysts have been prepared by impregnation methods via different reduction processes and used for catalytic decomposition of benzene. The oxidized and reduced catalysts exhibit apparent differences in physical/chemical features and catalytic activities for benzene oxidation. Metallic Pt nanoparticles have strong capacity for oxygen activation, and the negative charges and rich chemisorbed oxygen on the surface of metallic Pt nanoparticles are probably responsible for their high catalytic activities for benzene oxidation. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Periodate oxidation followed by borohydride reduction converts the well-known antithrombotics heparin and low-molecular-weight heparins (LMWHs) into their 'glycol-split' (gs) derivatives of the 'reduced oxyheparin' (RO) type, some of which are currently being developed as potential anti-cancer and anti-inflammatory drugs. Whereas the structure of gs-heparins has been recently studied, details of the more complex and more bioavailable gs-LMWHs have not been yet reported. We obtained RO derivatives of the three most common LMWHs (tinzaparin, enoxaparin, and dalteparin) and studied their structures by two-dimensional nuclear magnetic resonance spectroscopy and ion-pair reversed-phase high-performance liquid chromatography coupled with electrospray ionization mass spectrometry. The liquid chromatography-mass spectrometry (LC-MS) analysis was extended to their heparinase-generated oligosaccharides. The combined NMR/LC-MS analysis of RO-LMWHs provided evidence for glycol-splitting-induced transformations mainly involving internal nonsulfated glucuronic and iduronic acid residues (including partial hydrolysis with formation of 'remnants') and for the hydrolysis of the gs uronic acid residues when formed at the non-reducing ends (mainly, in RO-dalteparin). Evidence for minor modifications, such as ring contraction of some dalteparin internal aminosugar residues, was also obtained. Unexpectedly, the N-sulfated 1,6-anhydromannosamine residues at the enoxaparin reducing end were found to be susceptible to the periodate oxidation. In addition, in tinzaparin and enoxaparin, the borohydride reduction converts the hemiacetalic aminosugars at the reducing end to alditols. Typical LC-MS signatures of RO-derivatives of individual LMWH both before and after digestion with heparinases included oligosaccharides generated from the original antithrombin-binding and 'linkage' regions. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Diverse associations between methanotrophic archaea (ANME) and sulfate-reducing bacterial groups (SRB) often co-occur in marine methane seeps; however, the ecophysiology of these different symbiotic associations has not been examined. Here, we applied a combination of molecular, geochemical and Fluorescence in situ hybridization (FISH) coupled to nanoscale secondary ion mass spectrometry (FISH-NanoSIMS) analyses of in situ seep sediments and methane-amended sediment incubations from diverse locations (Eel River Basin, Hydrate Ridge and Costa Rican Margin seeps) to investigate the distribution and physiology of a newly identified subgroup of the Desulfobulbaceae (seepDBB) found in consortia with ANME-2c archaea, and compared these with the more commonly observed associations between the same ANME partner and the Desulfobacteraceae (DSS). FISH analyses revealed aggregates of seepDBB cells in association with ANME-2 from both environmental samples and laboratory incubations that are distinct in their structure relative to co-occurring ANME/DSS consortia. ANME/seepDBB aggregates were most abundant in shallow sediment depths below sulfide-oxidizing microbial mats. Depth profiles of ANME/seepDBB aggregate abundance revealed a positive correlation with elevated porewater nitrate relative to ANME/DSS aggregates in all seep sites examined. This relationship with nitrate was supported by sediment microcosm experiments, in which the abundance of ANME/seepDBB was greater in nitrate-amended incubations relative to the unamended control. FISH-NanoSIMS additionally revealed significantly higher 15N-nitrate incorporation levels in individual aggregates of ANME/seepDBB relative to ANME/DSS aggregates from the same incubation. These combined results suggest that nitrate is a geochemical effector of ANME/seepDBB aggregate distribution, and provides a unique niche for these consortia through their utilization of a greater range of nitrogen substrates than the ANME/DSS. [ABSTRACT FROM AUTHOR]

A novel flash ironmaking process based on hydrogen-containing reduction gases is under development at the University of Utah. The goal of this work was to study the possibility of the re-oxidation of iron particles in a H 2-H 2O gas mixture in the lower part of the flash reactor from the kinetic point of view. The last stage of hydrogen reduction of iron oxide, i.e., the reduction of wustite, is limited by equilibrium. As the reaction mixture cools down, the re-oxidation of iron could take place because of the decreasing equilibrium constant and the high reactivity of the freshly reduced fine iron particles. The effects of temperature and H 2O partial pressure on the re-oxidation rate were examined in the temperature range of 823 K to 973 K (550 °C to 700 °C) and H 2O contents of 40 to 100 pct. The nucleation and growth kinetics model was shown to best describe the re-oxidation kinetics. The partial pressure dependence with respect to water vapor was determined to be of first order, and the activation energy of re-oxidation reaction was 146 kJ/mol. A complete rate equation that adequately represents the experimental data was developed. [ABSTRACT FROM AUTHOR]

Defect sites in titania have a substantial effect on many thermal and photochemical reactions. Three common types of defects are titanium interstitials, oxygen vacancies and oxygen adatoms-all of which can react with organic molecules adsorbed on the surface. We look broadly at thermal reduction and photochemical oxidation reactions of oxygenates. In particular, we focus on the reductive coupling of benzaldehyde, the photo-oxidation of butyrophenone, the photostability of benzoic acid, and the photo-oxidative coupling of methanol to methyl formate. Methods used include temperature programmed reaction spectroscopy, scanning tunneling microscopy, and density functional theory. [ABSTRACT FROM AUTHOR]

The rhenium- and ruthenium-containing catalysts are active in the oxidation of CH and CO and in the reduction of NO. Comparative testing of catalyst samples under laboratory conditions and on an engine stand demonstrated that these catalysts outperform the known commercial catalysts in the neutralization of exhaust gas from automotive gasoline engines. It is, therefore, possible to completely replace expensive Rh and partially replace Pt and Pd with cheaper components-Re and Rh-in the manufacturing of catalytic converters. [ABSTRACT FROM AUTHOR]

Anaerobic oxidation of methane (AOM) is critical for controlling the flux of methane from anoxic environments. AOM coupled to iron, manganese and sulphate reduction have been demonstrated in consortia containing anaerobic methanotrophic (ANME) archaea. More recently it has been shown that the bacterium Candidatus 'Methylomirabilis oxyfera' can couple AOM to nitrite reduction through an intra-aerobic methane oxidation pathway. Bioreactors capable of AOM coupled to denitrification have resulted in the enrichment of 'M. oxyfera' and a novel ANME lineage, ANME-2d. However, as 'M. oxyfera' can independently couple AOM to denitrification, the role of ANME-2d in the process is unresolved. Here, a bioreactor fed with nitrate, ammonium and methane was dominated by a single ANME-2d population performing nitrate-driven AOM. Metagenomic, single-cell genomic and metatranscriptomic analyses combined with bioreactor performance and 13C- and 15N-labelling experiments show that ANME-2d is capable of independent AOM through reverse methanogenesis using nitrate as the terminal electron acceptor. Comparative analyses reveal that the genes for nitrate reduction were transferred laterally from a bacterial donor, suggesting selection for this novel process within ANME-2d. Nitrite produced by ANME-2d is reduced to dinitrogen gas through a syntrophic relationship with an anaerobic ammonium-oxidizing bacterium, effectively outcompeting 'M. oxyfera' in the system. We propose the name Candidatus 'Methanoperedens nitroreducens' for the ANME-2d population and the family Candidatus 'Methanoperedenaceae' for the ANME-2d lineage. We predict that 'M. nitroreducens' and other members of the 'Methanoperedenaceae' have an important role in linking the global carbon and nitrogen cycles in anoxic environments. [ABSTRACT FROM AUTHOR]

Molecular and crystal structures are determined for amino-substituted nitronyl nitroxide 1, the products of its subsequent oxidation, acylation, and reduction: zwitter-ions 3a, 3b and salts K( 4b) and K( 4b)(CFCO). [ABSTRACT FROM AUTHOR]

The oxidation state of palladium in a model Pd/ACZ three-way catalyst was monitored by synchronous XANES and mass spectrometry during two consecutive heating (to 850 °C) and cooling (to 100 °C) cycles under stoichiometric conditions simulating exhaust after treatment of a natural gas engine. During heating in the first cycle, PdO reduction occurred around 500 °C and the initial fully oxidized state of Pd was never recovered upon heating and cooling cycles. A mixed Pd/Pd oxidation state was at work in the second cycle. Hence, the operando XANES study reveals that the PdO/Pd pair exists in a working catalyst but is less active than the catalyst in its initial state of fully oxidized palladium. It is also evident from XANES spectra that ceria-zirconia promotes re-oxidation of metallic Pd, thus reasonably sustaining catalytic activity after exposure to high temperatures. [ABSTRACT FROM AUTHOR]

Catalysts with highly dispersed palladium on alumina, alumina doped with 20 wt% ceria and ceria have been prepared, characterized and examined for net-lean methane oxidation. In particular, the activity and selectivity were investigated during rich/lean cycling of the feed. The ceria content is found to influence both the general and the instantaneous activity responses. The results indicate that the active phase of palladium changes between reduced and oxidised Pd during the rich/lean cycling, and that the process is influenced by the presence of ceria. [ABSTRACT FROM AUTHOR]

The aim of this work is to evaluate the feasibility of preparation of Nb10Hf1Ti alloy by magnesiothermic reduction of its oxides. DTA studies were conducted to identify the reduction temperature for co reduction of the mixed oxides of NbO, HfO, and TiO by magnesium under reducing atmosphere. Based on DTA analysis, experiments were carried out to prepare Nb10Hf1Ti alloy by magnesiothermic reduction of their oxides at 750 °C. The reduced product was analyzed for its phases by X-ray diffraction. The excess Mg was leached out, the alloy mixture was vacuum dried, pelletized, sintered, and electron beam melted to get a consolidated alloy of the required composition. The alloy was characterized using different techniques such as optical microscopy, scanning electron microscopy, and chemical analysis. Microstructural observations revealed the formation of coarse grain structure in the consolidated alloy. The alloy product was also evaluated for its micro hardness. [ABSTRACT FROM AUTHOR]

A palladium containing metal-organic framework (MOF) compound has been synthesized from MOF, (ZnO)(BDC-NH)(BTB) through Schiff base condensation reaction and complexation of Pd(II). Pd-MOF was found to be an effective heterogeneous catalyst for the oxidation and hydrogenation of various substrates under mild reaction conditions. This catalytic method is highly active and shape selective. Graphical Abstract: [InlineMediaObject not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Heterogeneous reactions of tested particles proceeding on electroactive films with different kinds of thin pores are described formally in terms of diffusion equations complicated with an accompanying volume reaction inside the film interior. As it is shown, in polarization curves of such processes, there might appear limiting flows, which are essentially smaller than the limiting diffusion flow of tested particles in the bathing electrolyte. These flows should not depend on a film pores' topology, but be determined by the ratio of the total surface of pores and the visible film one. The obtained results are compared with those followed for the case when tested particles actually inculcate into the film matrix and react with either oxor red-fragments of the film. Identification criteria of the compared mechanisms are discussed. [ABSTRACT FROM AUTHOR]

A promising chemical absorption-biological reduction integrated process has been proposed. A major problem of the process is oxidation of the active absorbent, ferrous ethylenediaminetetraacetate (Fe(II)EDTA), to the ferric species, leading to a significant decrease in NO removal efficiency. Thus the biological reduction of Fe(III)EDTA is vitally important for the continuous NO removal. Oxygen, an oxidizing agent and biological inhibitor, is typically present in the flue gas. It can significantly retard the application of the integrated process. This study investigated the influence mechanism of oxygen on the regeneration of Fe(II)EDTA in order to provide insight on how to eliminate or decrease the oxygen influence. The experimental results revealed that the dissolved oxygen and Fe(III)EDTA simultaneously served as electron acceptor for the microorganism. The Fe(III)EDTA reduction activity were directly inhibited by the dissolved oxygen. When the bioreactor was supplied with 3% and 8% oxygen in the gas phase, the concentration of initial dissolved oxygen in the liquid phase was 0.28 and 0.68 mg l. Correspondingly, the instinct Fe(III)EDTA reduction activity of the microorganism determined under anoxic condition in a rotation shaker decreased from 1.09 to 0.84 and 0.49 mM h. The oxidation of Fe(II)EDTA with dissolved oxygen prevented more dissolved oxygen access to the microorganism and eased the inhibition of dissolved oxygen on the microorganisms. [ABSTRACT FROM AUTHOR]

The effect of Cu loading on the selective catalytic reduction of NO by NH was examined over a series of Cu ion-exchanged (20-80%) SSZ-13 zeolite catalysts. High NO reduction efficiencies (80-95%) were obtained over all catalyst samples between 250 and 500 °C, and at the gas hourly space velocity of 200,000 h. Both NO reduction and NH oxidation activities under these conditions were found to increase slightly with increasing Cu loading at low temperatures. However, NO reduction activity was suppressed with increasing Cu loadings at high temperatures (>500 °C) due to excess NH oxidation. The optimum Cu ion exchange level appears to be ~40-60% since higher than 80% NO reduction efficiency was obtained over 50% Cu ion-exchanged SSZ-13 up to 600 °C. The NO oxidation activity of Cu-SSZ-13 was found to be low regardless of Cu loading, although it was somewhat improved with increasing Cu ion exchange level at high temperatures. During the 'fast' SCR (i.e., NO/NO = 1), only a slight improvement in NO reduction activity was obtained for Cu-SSZ-13. Regardless of Cu loading, near 100% selectivity to N was observed; only a very small amount of NO was produced even in the presence of NO. The apparent activation energies for NO oxidation and NO SCR were estimated to be ~58 and ~41 kJ/mol, respectively. Graphical Abstract: [Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

Copper monoxide (CuO) was successfully obtained by microwave-assisted hydrothermal method, using different conditions-in a solution without base, in a solution alkalinized with NaOH or with NHOH. The powders were analyzed by thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared spectroscopy, UV-Visible spectroscopy, and scanning electronic microscopy. XRD results showed that CuO was obtained with monoclinic structure and without secondary phases. Thermal analysis and infrared spectra indicated the presence of acetate groups on the powder surface. TG curves also showed a mass gain assigned to the Cu(I) oxidation indicating that a reduction possibly occurred during synthesis. The high and broad absorption band in the UV-Vis spectroscopy from 250 to 750 nm indicated the coexistence of Cu(II) and Cu(I), confirming the Cu(II) reduction, inside the CuO lattice. It was also possible to confirm the Cu(II) reduction by a displacement of the Me-O vibration bands observed in the IR spectra at around 500 cm. [ABSTRACT FROM AUTHOR]

Polymer-free Pt/graphene nanosheet (GN) composites have been rapidly prepared by a one-step microwave-assisted reduction method, carried out by ethylene glycol reduction of HPtCl in a graphene oxide suspension. Several analytic techniques including UV-vis spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy have been used to characterize the resulting Pt/GN composites. It suggests that such composites exhibit good catalytic activity toward methanol oxidation. [ABSTRACT FROM AUTHOR]

Tin and titanium dioxides and their compositions were studied as catalysts for the reaction of complete oxidation of methane. The catalytic activity of the test samples was compared in terms of first-order reaction rate constants with reference to the unit surface area of a catalyst. The crystal structures and specific surface areas of the obtained compositions were characterized. The thermal stability of SnO was investigated. Data on the temperature-programmed reduction of SnO and the composition SnTiO in hydrogen were given. [ABSTRACT FROM AUTHOR]

Nanostructured VO(B) was prepared by employing glycerol as reductant. Key parameters of the pH value of crystallization solution and the volume ratio of glycerol to water were optimized to prepare pure phase VO(B). The VO(B) could catalyze the aerobic oxidation of benzene to phenol with molecular oxygen in high selectivity. [ABSTRACT FROM AUTHOR]

The formation of the equilibrium Cr(III) ↔ Cr(VI) in colored optical glasses under the combined effect of acid-base properties of the matrix, the total concentration of chromium, and the amount of other variable-valence elements which are in the oxidation - reduction series to the right of chromium is examined. It is shown that this equilibrium is related with the change of the spectral characteristics of the glass. [ABSTRACT FROM AUTHOR]

Oxidation of Pu(III) in 1 bp solution to Pu(IV) was studied using the salt-free oxidant NO. It was proved that the reductants N,N-dimethylhydroxylamine (DMHAN) and monomethyl-hydrazine (MMH) present in 1 bp solution of CIAE-APOR process can be oxidized and removed from the solutions also by NO before the oxidation of Pu(III). The effects of the acidity, the temperature and the amount of NO added on the oxidation of DMHAN and MMH were studied. [ABSTRACT FROM AUTHOR]

series of novel six iridium complexes ( 1-6) bearing two substituted phenylimidazole and an additional acetylacetone as the third co-auxilary ligand are reported. The lowest absorption band for all iridium complexes consist of a mixture of heavy atom Ir(III) enhanced MLCT and π-π* transitions and the phosphorescent peak wavelength can be fine-tuned to cover the spectral range 455-518 nm with high quantum efficiencies. The peak wavelength of the dopants can be finely tuned depending upon the electronic properties of the substituents. On the basis of onset potentials of the oxidation and reduction, the HOMO-LUMO energies were calculated and the reported iridium complexes emit green light with exceeding higher efficiency. [ABSTRACT FROM AUTHOR]

Subsurface geochemical behavior of As(V) with Fe(II) was studied under strict anoxic conditions. Abiotic reduction of As(V) (0.1 mM) to As(III) by aqueous Fe(II) and sorbed Fe(II) in pH range 5.0-7.0 and Fe(II) concentration (0.6-1.2 mM) was investigated along with the effect of As(V) on the oxidation of Fe(II) by dissolved oxygen (DO). Although the reduction was thermodynamically feasible for homogeneous chemical conditions, practically no As(V) reduction by aqueous Fe(II) was observed. Similarly, no sorbed As(V) reduction was observed under the heterogeneous experimental conditions by sorbed Fe(II) onto synthetic iron oxide (hematite, α-FeO). Experimental results on Fe(II) oxidation by DO in the presence of 0.1 mM As(V) showed a significantly slower Fe(II) oxidation, which might be due to the formation of Fe(II)-As(V) complex in the aqueous phase. The results of this study demonstrate that As(V) is relatively stable in the presence of Fe(II) under subsurface environment and interfere the oxidation of Fe(II). [ABSTRACT FROM AUTHOR]

new carbon-supported PdNi (PdNi/C) catalyst is prepared by a simple simultaneous reduction reaction with sodium borohydride in glycol solution. The results show that the performance of PdNi/C catalyst for formic acid oxidation is greatly improved compared with that of Pd/C. X-ray diffraction (XRD) results show that Ni exists in the catalyst both as NiO and as PdNi alloy. The value of the apparent activation energy shows that the activity of formic acid oxidation on the PdNi/C is more sensitive to temperature compared with Pd/C. [ABSTRACT FROM AUTHOR]

Thin films of pure Pd and composite of Pd and 1% multiwalled carbon nanotube have been obtained on glassy carbon electrodes by borohydride reduction method and investigated as electrocatalysts for the oxidation of phenol in acid medium at 25 °C, using cyclic voltammetry (CV), chronopotentiometry, and high-performance liquid chromatography. The CV study showed that both the electrocatalysts are quite stable and active for the phenol oxidation in acid medium. Further, these electrodes do not seem to undergo deactivation due to intermediates and products formed during the phenol oxidation. With the increase in phenol concentration from 2 to 25 mM, the peak current ( I) increases initially, reaches maximum at about 15 mM, and tends to decrease thereafter. The peak potential ( E) value was found to be practically unchanged with phenol concentration. The rate for phenol oxidation ( I) at the surface of both the electrocatalysts increased with the decrease in pH of the reaction mixture. The electrocatalytic activity of the composite electrode was, however, higher than that of pure Pd under similar experimental conditions. Benzoquinone and hydroquinone were identified as the major phenol degradation intermediate products. [ABSTRACT FROM AUTHOR]

Enantiospecific microbial reduction of bicyclic ketones was described. Racemic Wieland-Miescher ( 1) and Hajos-Parrish ( 2) ketones were used as substrates. In a 4-h biotransformation of Hajos-Parrish ketone ( 2) using the strain of Didymosphaeria igniaria an optically pure ketone ( R)- 2 was obtained, whereas the ( S)- 2 ketone underwent reduction to (4a S,5 S)- 4 alcohol with 100% of enantiomeric excess and with over 60% of diastereoisomeric excess. Jones oxidation of the alcohol obtained in the biotransformation gave an optically pure ketone ( S)- 2. Enzymatic system of Coryneum betulinum reduced the ( R)- 2 ketone to (4a R,5 S)- 4 alcohol with a high enantiomerical purity in a 6-day reaction. Wieland-Miescher ( 1) ketone was transformed by these microorganisms in an analogous way, but the reaction times were longer. [ABSTRACT FROM AUTHOR]

Significant increases in root density, crop growth and productivity have been observed following soil additions of biochar, which is a solid product from the pyrolysis of biomass. In addition, alterations in the soil microbial dynamics have been observed following biochar amendments, with decreased carbon dioxide (CO2) respiration, suppression of methane (CH4) oxidation and reduction of nitrous oxide (N2O) production. However, there has not been a full elucidation of the mechanisms behind these effects. Here we show data on ethylene production that was observed from biochar and biochar-amended soil. Ethylene is an important plant hormone as well as an inhibitor for soil microbial processes. Our current hypothesis is that the ethylene is biochar derived, with a majority of biochars exhibiting ethylene production even without soil or microbial inoculums. There was increased ethylene production from non-sterile compared to sterile soil (215%), indicating a role of soil microbes in the observed ethylene production. Production varied with different biomass sources and production conditions. These observations provide a tantalizing insight into a potential mechanism behind the biochar effects observed, particularly in light of the important role ethylene plays in plant and microbial processes. [ABSTRACT FROM AUTHOR]

The behavior of molybdenum(III), tungsten(IV), and uranium(VI) ions in NaCl-2CsCl-eutectic-mixture-based melt at 550°C is studied by spectroelectrochemical method. Anodic oxidation of MoCl and WCl yields melt-soluble chloride compounds MoCl and WCl respectively. It is shown that the electrochemical recharging in the Mo(III)/Mo(IV) system is reversible; the formal standard potential E*Mo(IV)/Mo(III)and the Gibbs energy $$ \Delta G_{MoCl_4 (melt)}^* $$ are evaluated. The cathodic reduction of U(VI) yields U(V) ions. The cathodic reduction of W(IV) ion does not yield melt-soluble tungsten compounds of lower oxidation state. [ABSTRACT FROM AUTHOR]