Redox Shift Research Articles

The utilization of dye wastewater in enhancing catalytic activity of CeO2-TiO2 mixed oxide catalyst for NO reduction and dichloromethane oxidation

Waste is a misplaced resource. Herein, anionic (orange II sodium salt and Ponceau 2R) and cationic (Rhodamine B and Methylene blue) dye wastewater assisted photo-treatment (referred as DAPT) method was developed to modify sol-gel synthesized CeO2-TiO2 (CeTi) mixed oxide catalyst. Catalytic activity test results showed that both anionic and cationic dye wastewater could be used as “fuel” of photo-treatment to enhance the activity of CeTi catalyst in NO reduction and dichloromethane oxidation. Characterization and DFT calculation results revealed that DAPT process increased the amount of Ce3+ ions on CeTi samples, which could induce the formation of Ce–VO–Ti (oxygen vacancy (VO) in Ce–O–Ti short range structure). These Ce–VO–Ti defects not only could be adsorption sites for NH3, dichloromethane and oxygen, but also promoted the redox shift of Ce3++ Ti4+ ⇋ Ce4++ Ti3+ by enhancing the oxidizability of Ce4+ and Ti4+ species. Furthermore, defects changed the polarity of Ce–O and Ti–O, which was conducive to the activation of lattice oxygen. All these improvements contributed to the excellent catalytic activity of CeTi catalysts. We expected this work to be instructive on constructing structure-activity over CeO2-TiO2 based catalysts and utilizing dye wastewater.

Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formation

Abstract. The eastern Mediterranean Sea sedimentary record is characterised by intervals of organic-rich sapropel sediments, indicating periods of severe anoxia triggered by astronomical forcing. It has been hypothesised that nitrogen fixation was crucial in injecting the Mediterranean Sea with bioavailable nitrogen (N) during sapropel events. However, the evolution of the N biogeochemical cycle of sapropels is poorly understood. For example, the role of the complementary removal reactions like anaerobic ammonium oxidation (anammox) has not been investigated because the traditional lipid biomarkers for anammox, ladderane fatty acids, are not stable over long periods in the sedimentary record. Using an alternative lipid biomarker for anammox, bacteriohopanetetrol stereoisomer (BHT isomer), we present here for the first time N removal throughout the progression, e.g. formation, propagation, and termination, of basin-wide anoxic events. BHT isomer and ladderanes were analysed in sapropel records taken from three eastern Mediterranean sediment cores, spanning S1 to Pliocene sapropels. Ladderanes were rapidly degraded in sediments, as recently as the S5 sapropel. BHT isomer, however, was present in all sapropel sediments, as far back as the Pliocene, and clearly showed the response of anammox bacteria to marine water column redox shifts in high-resolution records. Two different N removal scenarios were observed in Mediterranean sapropels. During S5, anammox experienced Black Sea-type water column conditions, with the peak of BHT isomer coinciding with the core of the sapropel. Under the alternative scenario observed in the Pliocene sapropel, the anammox biomarker peaked at onset and termination of said sapropel, which may indicate sulfide inhibition of anammox during the core of sapropel deposition. This study shows the use of BHT isomer as a biomarker for anammox in the marine sediment record and highlights its potential in reconstructing anammox during past anoxic events that are too old for ladderanes to be applied, e.g. the history of oxygen minimum zone expansion and oceanic anoxic events.

New insight into simultaneous removal of NO and Hg0 on CeO2-modified V2O5/TiO2 catalyst: A new modification strategy

In this work, it was theoretically speculated that enhancing NO adsorption will simultaneously improve SCR performance and Hg0 oxidation on a V-based SCR catalyst. As a result, CeO2 was selected as the modification component. The results indicated that CeO2 modification not only significantly improved SCR performance but also apparently enhanced Hg0 oxidation. Hg-TPD results suggest that Hg0 can be oxidized to Hg(NO3)2 but that it was hard to desorb from the catalyst, leading to the blockage of active sites. It was found that HCl facilitated the desorption of adsorbed Hg(NO3)2, which enabled the recovery of active sites. An innovative nitrate pathway for Hg0 oxidation was proposed in this work. In situ FTIR experiments indicated that NO can strongly adsorb and generate more nitrite species on a V1CeTi catalyst, with bidentate nitrate species playing an important role in Hg0 oxidation. Additionally, SO2 and H2O (g) showed no obvious influence on SCR performance, while decreasing the Hg0 oxidation efficiency at high temperatures. X-ray photoelectron spectroscopy (XPS) analysis revealed that SO2 can react with CeO2 to form Ce2(SO4)3, which partially blocked the redox shift between Ce3+ and Ce4+. The proposed nitrate pathway in this work provided a new design and modification strategy for catalysts used for simultaneous removal of NO and Hg0.

Site-Specific Proteomic Mapping of Modified Cysteine Residues.

The wide reactivity of the thiol group enables the formation of a number of chemically and biologically distinct posttranslational modifications. Proteins within nearly all major families undergo some form of cysteine modification and the modifications are associated with regulatory functions across many biological processes. However, the susceptibility of thiols to redox shifts, as well as the labile nature of most thiol modifications, renders detection difficult. Analysis difficulties are compounded further in complex protein mixtures due to the typical low abundance of cysteine modifications under normal physiological conditions. Here we describe methods for the analysis of three cysteine modifications: nitrosylation, glutathionylation, and S-acylation. The three methods use the same organic mercury-conjugated agarose resin as an enrichment platform. To date, over 2154 sites on 1446 proteins have been identified between the three modifications using this method. Using equivalent processing, enrichment, and analytical methods has enabled a more comprehensive picture of the redox proteome landscape.

Redox poise and metabolite changes in bread wheat seeds are advanced by priming with hot steam.

Fast and uniform germination is key to agricultural production and can be achieved by seed 'priming' techniques. Here, we characterised the responses of bread wheat (Triticum aestivum L.) seeds to a hot steam treatment ('BioFlash'), which accelerated water uptake, resulting in faster germination and seedling growth, typical traits of primed seed. Before the completion of germination, metabolite profiling of seeds revealed advanced accumulation of several amino acids (especially cysteine and serine), sugars (ribose, glucose), and organic acids (glycerate, succinate) in hot steam-treated seeds, whereas sugar alcohols (e.g. arabitol, mannitol) and trehalose decreased in all seeds. Tocochromanols (the 'vitamin E family') rose independently of the hot steam treatment. We further assessed shifts in the half-cell reduction potentials of low-molecular-weight (LMW) thiol-disulfide redox couples [i.e. glutathione disulfide (GSSG)/glutathione (GSH) and cystine/cysteine], alongside the activities of the reactive oxygen species (ROS)-processing enzyme superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. Upon the first 4 h of imbibition, a rapid conversion of LMW disulfides to thiols occurred. Completion of germination was associated with a re-oxidation of the LMW thiol-disulfide cellular redox environment, before more reducing conditions were re-established during seedling growth, accompanied by an increase in all ROS-processing enzyme activities. Furthermore, changes in the thiol-disulfide cellular redox state were associated to specific stages of wheat seed germination. In conclusion, the priming effect of the hot steam treatment advanced the onset of seed metabolism, including redox shifts associated with germination and seedling growth.

Multistep Explicit Solvation Protocol for Calculation of Redox Potentials.

The calculation of molecular redox potentials in aqueous solution presents a challenge to quantum chemistry due to the need to calculate charged, open-shell species experiencing large solvent effects. Traditionally, redox potentials are calculated via the use of density functional theory and continuum solvation methods, but such protocols have been found to often suffer from large errors, particularly in the case of aqueous solution. While explicit solvation models hold promise of higher accuracy to describe solvent effects in general, their complicated use and lack of well-defined, reliable protocols has hindered their adoption. In this study, we present an explicit-solvation-based approach for the calculation of molecular redox potentials. We combine the use of affordable semiempirical QM/MM molecular dynamics (making use of the recently proposed GFN-xTB method by Grimme et al.) for both redox states and use the linear response approximation to relate vertical ionization energies to the adiabatic redox potential. Simulation length, averaging over snapshots, and accounting for bulk and polarization effects are systematically evaluated using phenol as a working example. We find that it is crucial to reliably account for bulk solvation effects in these calculations, as well as polarization effects which we divide up into short-range and long-range contributions. The short-range polarization contribution is accounted for via QM-region expansion, while the long-range contribution is accounted for via Drude-polarizable QM/MM. Our multistep protocol has been coded to be used in a fully automatic way in a local version of Chemshell. It has been evaluated on a test set of oxidation potentials of organic molecules and found to give gas-solution redox shifts with a mean absolute error of 0.13 eV with respect to experiment, compared to mean absolute errors of 0.26 and 0.21 eV with CPCM and SMD continuum models, respectively.

Microsomal pre-receptor cortisol production is inhibited by resveratrol and epigallocatechin gallate through different mechanisms.

Local activation of cortisol in hormone target tissues is a major determinant of glucocorticoid effect. Disorders in this peripheral cortisol metabolism play an important role in the development of metabolic diseases, such as obesity or type 2 diabetes mellitus. Hence, dietary factors influencing the activity of the involved enzymes can have major impacts on the risk of the above diseases. Resveratrol and epigallocatechin gallate (EGCG), two natural polyphenols found in several nutriments and in green tea, respectively, are well-known for their antiobesity and antidiabetic activities. EGCG has been shown to interfere with microsomal cortisol production through decreasing the luminal NADPH:NADP+ ratio. The aim of this study was to clarify if resveratrol also induces such a redox shift or causes any direct enzyme inhibition that influences local cortisol production. Cortisone-cortisol conversions and changes in NADPH levels were monitored in rat liver microsomal vesicles. Cortisol production was inhibited by resveratrol in a concentration dependent manner while the intrinsic reducing and oxidizing capacity as well as the NADPH level inside the ER-derived vesicles remained unaffected. Activity measurements performed in permeabilized microsomes confirmed that resveratrol, unlike EGCG, inhibits 11β-hydroxysteroid dehydrogenase type 1 directly. Long-term moderation of pre-receptor cortisol production likely contributes to the beneficial health effects of both polyphenols. © 2018 BioFactors, 45(2):236-243, 2019.

Redox state affects fecundity and insecticide susceptibility in Anopheles gambiae

Redox reactions play a central role in the metabolism of an organism. It is vital to maintain redox homeostasis in response to the fluctuation of redox shift in various biological contexts. NADPH-dependent reducing capacity is one of the key factors contributing to the redox homeostasis. To understand the redox capacity and its impact on mosquito fecundity and susceptibility to insecticides in Anopheles gambiae, we examined the dynamics of elevated oxidative state via induction by paraquat (PQ) and the inhibition of NADPH regeneration by 6-aminonicotinamide (6AN). In naïve conditions, inherent oxidative capacity varies between individuals, as measured by GSSG/GSH ratio. The high GSSG/GSH ratio was negatively correlated with fecundity. Both PQ and 6AN feeding increased GSSG/GSH ratio and elevated protein carbonylation, a marker of oxidative damage. Both pro-oxidants lowered egg production. Co-feeding the pro-oxidants with antioxidant lycopene attenuated the adverse effects on fecundity, implying that oxidative stress was the cause of this phenotype. Pre-feeding with 6AN increased insecticide susceptibility in DDT resistant mosquitoes. These results indicate that oxidative state is delicate in mosquitoes, manipulation of NADPH pool may adversely affect fecundity and insecticide detoxification capacity. This knowledge can be exploited to develop novel vector control strategies targeting fecundity and insecticide resistance.

A simple but effective ferrocene derivative as a redox, and fluorescent receptor for highly selective recognition of Al3+ ions

A new probe, based on BINOL and ferrocene unit, senses Al3+ selectively among a variety of metal cations. Through different channels: anodic redox shift of the Fe(II)/Fe(III) redox couple, and a remarkable enhancement of the fluorescence. This fluorescence recognition of Al3+ also shows color changes under a UV lamp. Mass and NMR spectroscopic analyses have been used to study the mechanism, which indicates the formation of [1 + 2] complexes.

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20th century

Abstract. The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment. Here we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated the depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented and, in addition to gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. Alongside the anthropogenic nutrient input, the progressive deoxygenation since the beginning of the 1900s was fueled by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s. We find no evidence of similar anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality.

Evidence for episodic oxygenation in a weakly redox-buffered deep mid-Proterozoic ocean

Over the last two decades, popular opinion about prevailing conditions in the mid-Proterozoic deep ocean has evolved from fully oxygenated to globally euxinic (sulfidic) to a more heterogeneous, stratified water column with localized pockets of euxinia existing in predominantly iron-rich (ferruginous) deep waters. The Animikie Basin in the Lake Superior region has been essential in shaping our view of marine redox evolution over this time period. In this study, we present a multi-proxy paleoredox investigation of previously unanalyzed strata of the late Paleoproterozoic Animikie Basin using drill cores through the ~1.85 Ga Stambaugh Formation (Paint River Group) in the Iron River-Crystal Falls district of the Upper Peninsula of Michigan, USA. Based on previous tectonic reconstructions and analysis of sedimentary regimes, the Iron River-Crystal Falls section captures strata from among the deepest-water facies of the Animikie Basin. In contrast to previous work on sedimentary rocks in this basin, we find evidence from iron speciation, trace metal, and Mo isotope data for episodes of at least local deep-water oxygenation within a basin otherwise dominated by ferruginous and euxinic conditions. While trace-metal enrichments and iron speciation data suggest predominantly anoxic conditions, the occurrence of Mn-rich intervals (up to 12.3 wt% MnO) containing abundant Mn-Fe carbonate, and a wide range of Mo isotope data with extremely negative values (δ98/95Mo = −1.0 to +1.1‰), record the shuttling of Mn-oxides from surface waters through oxic or suboxic waters to the sediment-water interface. We propose that such conditions are analogous to those of locally restricted modern and Holocene basins in the Baltic Sea, which receive episodic inflow of oxygenated water, producing similar geochemical signatures to those observed for the Animikie Basin. We argue that the mid-Proterozoic was characterized by a lack of a strong redox buffer (low sulfide, ferrous iron, and oxygen contents), and thus was vulnerable to dramatic, and at least local, redox shifts—including briefly oxygenated bottom waters. A refined view of the mid-Proterozoic ocean is emerging: one that was still predominantly anoxic, but marked by regional heterogeneities and short-term redox variability that may, in part, reflect a transitional state between prevailingly anoxic Archean and predominantly oxic Phanerozoic oceans.

Radium isotope response to aquifer storage and recovery in a sandstone aquifer

Radium isotopes and water-rock interaction were evaluated in an aquifer storage and recovery (ASR) pilot study conducted in 2010–2011 in Minnesota (USA) in order to identify mechanisms governing Ra activities when low-Ra water is recharged into a sandstone aquifer. Groundwater in the aquifer selected for the study, the Cambrian Mt. Simon Sandstone, contains naturally occurring radium that in many areas exceeds United States drinking water standards (185 mBq/L or 5 pCi/L combined 226Ra+228Ra), highlighting the need to identify the rates and mechanisms by which stored water acquires Ra isotopes. Major element concentrations of recovered water largely resembled recharged water, while Ra activities exceeded the Ra activities of the recharged water. 224Ra reached ∼100 mBq/L during the first 8 h of recovery (overall range 15.5–133 mBq/L). 226Ra and 228Ra also increased during the 47-day recovery period (23.7–82.5 mBq/L and 33.7–85.5 mBq/L, respectively). Ra isotope ratios indicate the relative contribution of alpha recoil vs. chemical processes (e.g. adsorption/desorption). During recovery, the 224Ra/228Ra and 228Ra/226Ra ratios declined, approaching their expected limiting values near unity. Collectively, the rates of Ra activity change with time, trends in Ra isotope ratios, barium concentrations, and manganese concentrations suggest that Ra was governed by chemical processes and alpha recoil, in which the half-lives of each Ra isotope determined the primary mechanism(s) controlling radionuclide mobilization from the aquifer solids. Radium-mobilizing processes during storage may include: (1) recharge of low-Ra water into an aquifer containing high-Ra groundwater induced adsorption/desorption disequilibrium and caused net Ra desorption; (2) chemical conditions during storage (e.g. the Ba content of the recharge water or the reducing conditions in the aquifer) could have further released Ra from the aquifer solids or reduced the effectiveness of Ra adsorption; and/or (3) mobilization from radioactive decay of solid-phase thorium parents (alpha recoil) contributed Ra isotopes into the low-Ra recharge water. The short-lived 224Ra was released dominantly by alpha recoil while the longer-lived 226Ra was dominantly released by chemical mechanisms such as desorption. Radium-228, of intermediate half-life, also appears to have been released predominantly by alpha recoil, although significant chemical release of 228Ra cannot be ruled out. Accordingly, at near-neutral pH, groundwater geochemical conditions (such as redox state and/or shifts in Ra activities or Ba concentrations) can influence observed Ra activities in recovered water, which in proportional terms impart the largest effect on the longer-lived 226Ra. Given the roles for both alpha recoil and chemical reactions, the duration of storage could influence radium activities in recovered water from ASR wells.

Drastic Redox Shift and Electronic Structural Changes of a Manganese(III)-Salen Oxidation Catalyst upon Reaction with Hydroxide and Cyanide Ion.

Flexible redox properties of a metal complex are important for redox catalysis. The present study shows that the reaction of a manganese(III) salen complex, which is a well-known oxidation catalyst, with hydroxide ion gives a transient manganese(III) species with drastically lowered redox potential, where the redox difference is -1.21 V. The reaction with cyanide ion gives a stable manganese(III) species with almost the same spectroscopic and redox properties, which was characterized as an anionic [MnIII(salen)(CN)2]- of low-spin S = 1 state, in contrast to the starting MnIII(salen)(OTf) having usual high-spin S = 2 manganese(III). The present study has thus clarified that the drastic redox shift comes from an anionic six-coordinate [MnIII(salen)(X)2]- species where X is either OH- or CN-. Resonance Raman measurements show that the stretching band of the imino group shifts from 1620 to 1597 cm-1 upon conversion from MnIII(salen)(OTf) to [MnIII(salen)(CN)2]-, indicative of lowered C═N double bond character for [MnIII(salen)(CN)2]-. The observed deformation of a salen ligand is a clear indication of an increased electron population on the imino π*-orbital upon formation of low-spin manganese(III). It was proposed that the electronic structure of [MnIII(salen)(CN)2]- may contain only limited contribution from valence tautomeric [MnIV(salen- •)(CN)2]-, in which the imino group of a salen ligand is reduced by one-electron via intramolecular electron transfer from low-spin manganese(III). The present study has clarified an unexpected new finding that a salen ligand works as a reservoir for negative charge to stabilize low-spin manganese(III).

Arsenite and arsenate immobilization by preformed and concurrently formed disordered mackinawite (FeS)

Arsenic (As) immobilization in aqueous environments is controlled by sorption and/or coprecipitation with iron (Fe) oxyhydroxides under oxic conditions and with ferrous iron (Fe(II)) and sulfide (S(-II)) minerals under anoxic conditions. Shifts to reducing conditions trigger the release of dissolved As by reductive dissolution of Fe oxyhydroxides. More stringent reducing conditions in sulfur (S) rich environments form solid S(-II) phases that immobilize As. This work studied the association of arsenite and arsenate with freshly-formed disordered mackinawite (FeS), a model Fe and reduced S mineral of environmental relevance. The association of As to preformed FeS (Set P experiments) was contrasted to the case when As is present during FeS precipitation (Set C experiments). Most abiotic studies of As reactivity under reducing conditions have been done under Set P setting, despite that redox shifts are likely to induce environments analogous to Set C experiments. Dissolved As removal was initially higher for Set C compared to Set P experiments at least by a factor of two, except for arsenate with low initial redox potential. Set C experiments had a rapid initial As sorption, followed by some As desorption. When stringent reducing conditions ensue, the extent and rate of As removal by FeS is misrepresented by sorption experiments to preformed FeS. A continuous release of As concurrent with the formation of thioarsenates - a dissolved form of As with weaker binding to Fe minerals - was observed in Set C experiments with arsenite. The formation of thioarsenates occurred preferably in Set C experiments at low redox potential, while it was negligible for arsenate experiments. Remarkably, the occurrence of thioarsenates disputes a widespread notion that their formation is inhibited by Fe(II)-S(-II) affinity and precipitation as FeS. This study shows the potential of FeS to scavenge arsenite and to decrease its mobility in reduced sediments and groundwater, and highlights the role of thioarsenates in As mobility in systems with changing redox conditions where the reactive solid forms in presence of the contaminant.

Low-Dose Dose-Response for In Vitro Nrf2-ARE Activation in Human HepG2 Cells.

Kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid 2-like factor 2-related factor 2 (Nrf2), and the antioxidant response element (ARE) are interacting components of a master regulatory signaling pathway that coordinates redox homeostasis, cytoprotective responses, and shifts in stem cell state. This study reexamined detailed dose–response (DR) data reported for in vitro Nrf2-ARE activation in human hepatoblastoma HepG2 cell lines containing either a ARE-bla or ARE-luc reporter at 12 different concentrations of each of 15 chemicals. The normalized study data were combined among chemicals exhibiting a positive response, yielding n = 531 (179) DR data for 9 (7) chemicals using the ARE-bla (ARE-luc) assay. Three-parameter linear/kth-power regression fits obtained to each combined set of ARE-bla- or ARE-luc-assay response data provided good fits (R 2 = .99 or .91, respectively, P fit > .99) that each incorporate a highly significant negative initial linear slope (P = 4 × 10−5 or .00025) and an overall J-shaped DR pattern. Results from this reanalysis of high-resolution ARE response data support the hypothesis that nonlinear ARE-mediated adaptive cellular responses to oxidative stress are governed by an ultrasensitive molecular switch.

Dynamics and energetics of cyanobacterial photosystem I:ferredoxin complexes in different redox states

Fast turnover of ferredoxin/Fd reduction by photosystem-I/PSI requires that it dissociates rapidly after it has been reduced by PSI:Fd intracomplex electron transfer. The rate constants of Fd dissociation from PSI have been determined by flash-absorption spectroscopy with different combinations of cyanobacterial PSIs and Fds, and different redox states of Fd and of the terminal PSI acceptor (FAFB). Newly obtained values were derived firstly from the fact that the dissociation constant between PSI and redox-inactive gallium-substituted Fd increases upon (FAFB) reduction and secondly from the characterization and elucidation of a kinetic phase following intracomplex Fd reduction to binding of oxidized Fd to PSI, a process which is rate-limited by the foregoing dissociation of reduced Fd from PSI. By reference to the complex with oxidized partners, dissociation rate constants were found to increase moderately with (FAFB) single reduction and by about one order of magnitude after electron transfer from (FAFB)− to Fd, therefore favoring turnover of Fd reduction by PSI. With Thermosynechococcus elongatus partners, values of 270, 730 and >10000s−1 were thus determined for (FAFB)Fdoxidized, (FAFB)−Fdoxidized and (FAFB)Fdreduced, respectively. Moreover, assuming a conservative upper limit for the association rate constant between reduced Fd and PSI, a significant negative shift of the Fd midpoint potential upon binding to PSI has been calculated (< −60mV for Thermosynechococcus elongatus). From the present state of knowledge, the question is still open whether this redox shift is compatible with a large (>10) equilibrium constant for intracomplex reduction of Fd from (FAFB)−.

The Effects of Conjugated Linoleic Acid and Berberine Supplementation on Markers of Oxidative Stress in Broiler Chickens

Reactive oxidative species (ROS) are oxygen base molecules that are leaked from the electron transport chain during mitochondrial cellular respiration. They are kept in balance by endogenous and exogenous antioxidants, which may include conjugated linoleic acid (CLA) and a plant root extract called berberine. A redox shift towards oxidants causes a state called oxidative stress, which is detrimental if prolonged. A ten week study examined the effect CLA and berberine supplementation on markers of oxidative stress in broiler birds. Broilers (n=60) were divided into six groups; the diet of group four to six included allopurinol (25mg/kg body weight) which induced an oxidative stress state. Pen 1(P1) served as the control, P2 CLA oil (50% substitution), P3 berberine supplementation (20g/kg feed), P4 allopurinol alone, P5 CLA oil + allopurinol and P6 berberine + allopurinol. Body weight, plasma uric acid as a marker of oxidative stress, blood glucose, lipid peroxidation via TBARs assay of serum, and relative gene expression of five endogenous liver antioxidants were measured during the course of the study. The addition of allopurinol to the diet induced an oxidative stress state when compared to the baseline groups as observed by a significant reduction in plasma uric acid. In P5 and P6 treatment we observed on average a 10 fold increase in the relative mRNA expression of superoxide dismutase 2 and 3 as well as glutathione 3 and 7. Notably, CLA increased the expression of uncoupling protein 34 fold compared to control while the addition of allopurinol blocked these changes; in contrast there was a slight increase in the berberine+allopurinol treatment. No significant changes were measured in blood glucose and TBARS. Despite the increase in mRNA expression of the antioxidants genes, the result of the uric acids assay suggest that at the dosages administered CLA and berberine were not effective in reversing the oxidative stress induced by allopurinol.Support or Funding InformationWVU Hatch

Impact of six lignocellulosic biochars on C and N dynamics of two contrasting soils

AbstractBoth soil and biochar properties are known to influence greenhouse gas emissions from biochar‐amended soils, but poor understanding of underlying mechanisms challenges prediction and modeling. Here, we examine the effect of six lignocellulosic biochars produced from the pyrolysis of corn stover and wood feedstocks on CO2 and N2O emissions from soils collected from two bioenergy cropping systems. Effects of biochar on total accumulated CO2‐C emissions were minimal (&lt;0.45 mg C g−1 soil; &lt;10% of biochar C), consistent with mineralization and hydrolysis of small labile organic and inorganic C fractions in the studied biochars. Comparisons of soil CO2 emissions with emissions from microbially inoculated quartz–biochar mixtures (‘quartz controls’) provide evidence of soil and biochar‐specific negative priming. Five of six biochar amendments suppressed N2O emissions from at least one soil, and the magnitude of N2O emissions suppression varied with respect to both biochar and soil types. Biochar amendments consistently decreased final soil NO3− concentrations, while contrasting effects on pH, NH4+, and DOC highlighted the potential for formation of anaerobic microsites in biochar‐amended soils and consequential shifts in the soil redox environment. Thus, results implicated both reduced substrate availability and redox shifts as potential factors contributing to N2O emission suppression. More research is needed to confirm these mechanisms, but overall our results suggest that soil biochar amendments commonly reduce N2O emissions and have little effect on CO2 emissions beyond the mineralization and/or hydrolysis of labile biochar C fractions. Considering the large C credit for the biochar C, we conclude that biochar amendments can reduce greenhouse gas emissions and enhance the climate change mitigation potential of bioenergy cropping systems.

линико-функциональные и метаболические нарушения и их коррекция у пациентов с дистальной сенсомоторной нейропатией

The clinical manifestations, biochemical and microhemocirculatory disorders, electroneuromographic (ENMG) changes in patients with distal sensomotor neuropathy and neuropathic pain syndrome including 16 persons of the comparison group (basic therapy) and 25 - of the main group (basic therapy + blood intravenous laser irradiation + nicergoline) at the time of hospitalization and after the course of treatment were studied. The patients showed a mixed, predominantly axonal type of nerve damage with the most pronounced changes in the ENMG indicators of sensory fibers in the lower limbs nerves. The use of blood intravenous laser irradiation and nicergoline contributes to a significant decrease in the activation of lipid peroxidation reactions and an increase in the activity of superoxide dismutase, while maintaining redox shifts characterized by lactic acid and an increase in the lactate / pyruvate ratio. Along with this, a significant reduction in the blood content of the substance P, was achieved in the patients of the main group. More effective correction of the disturbances in the vasomotor function of the endothelium was achieved. The obtained data confirm the pathogenetic validity of the use of blood intravenous laser irradiation and nicergoline for the treatment of patients with distal sensomotor neuropathy and neuropathic pain syndrome.

Patterns of local and global redox variability during the Cenomanian–Turonian Boundary Event (Oceanic Anoxic Event 2) recorded in carbonates and shales from central Italy

AbstractCareful evaluation of the local geochemical conditions in past marine settings can provide a window to the average redox state of the global ocean during episodes of extensive organic carbon deposition. These comparisons aid in identifying the interplay between climate and biotic feedbacks contributing to and resulting from these events. Well‐documented examples are known from the Mesozoic Era, which is characterized by episodes of widespread organic carbon deposition known as Oceanic Anoxic Events. This organic carbon burial typically leads to coeval positive carbon‐isotope excursions. Geochemical data are presented here for several palaeoredox proxies (Cr/Ti, V, Mo, Zn, Mn, Fe speciation, I/Ca and sulphur isotopes) from a section exposed at Furlo in the Marche–Umbrian Apennines of Italy that spans the Cenomanian–Turonian boundary. Here, Oceanic Anoxic Event 2 is represented by a ca 1 m thick radiolarian‐rich millimetre‐laminated organic‐rich shale known locally as the Bonarelli Level. Iron speciation data for thin organic‐rich intervals observed below the Bonarelli Level imply a local redox shift going into the Oceanic Anoxic Event, with ferruginous conditions (i.e. anoxic with dissolved ferrous iron) transiently developed prior to the event and euxinia (i.e. anoxic and sulphidic bottom waters) throughout the event itself. Pre‐Oceanic Anoxic Event enrichments of elements sensitive to anoxic water columns were due to initial development of locally ferruginous bottom waters as a precursor to the event. However, the greater global expanse of dysoxic to euxinic conditions during the Oceanic Anoxic Event greatly reduced redox‐sensitive trace‐metal concentrations in seawater. Pyrite sulphur isotopes document a positive excursion during the Oceanic Anoxic Event. Carbonate I/Ca ratios were generally low, suggesting locally reduced bottom‐water oxygen conditions preceding the event and relatively increased oxygen concentrations post‐event. Combined, the Furlo geochemical data suggest a redox‐stratified water column with oxic surface waters and a shallow chemocline overlying locally ferruginous bottom waters preceding the event, globally widespread euxinic bottom waters during the Oceanic Anoxic Event, followed by chemocline shallowing but sustained local redox stratification following the event.