Reduction In Oxygen Research Articles

Static Thermochemical Model of COREX Melter Gasifier

COREX is one of the commercial smelting reduction processes. It uses the finer size ore and semi-soft coal instead of metallurgical coke to produce hot metal from iron ore. The use of top gas with high calorific value as a by-product export gas makes the process economical and green. The predictive thermochemical model of the COREX process presented here enables rapid computation of process parameters such as (1) required amount of ore, coal, and flux; (2) amount of slag and gas generated; and (3) gas compositions (based on the raw material and desired hot metal quality). The model helps in predicting the variations in process parameters with respect to the (1) degree of metallization and (2) post-combustion ratio for given raw material conditions. In general reduction in coal, flux, and oxygen, the requirement is concomitant with an increase in the degree of metallization and post-combustion ratio. The model reported here has been benchmarked using industrial data obtained from the JSW Steel Plant, India.

Synthesis of N-hydroxy-imidamide-functionalized graphene: an efficient metal-free electrocatalyst for oxygen reduction

Metal-free electrocatalysts for oxygen reduction reaction (ORR) are key to the development of efficient, durable, and low-cost alternatives to noble-metal-based electrocatalysts in fuel cell cathodes. In recent years, many efforts are directed to the metal-free catalyst based on heteroatom-doped graphene. In this work, we demonstrate that the graphene surface can be converted into the catalyst for the oxygen reduction by chemical functionalization. In this context, we first synthesized malononitrile-functionalized graphene oxide. Amidoximation of nitrile group and reduction in graphene oxide were then carried out by hydroxylamine in one step. The electrochemical behavior of functionalized graphene-modified electrode for the reduction in oxygen was studied. The results showed that the electrocatalyst fabricated by this method exhibited striking catalytic activities in alkaline solution. In alkaline solution, this catalyst showed a competitive activity to the commercial Pt catalyst via four-electron transfer pathway with better ORR selectivity and stability. In addition, this metal-free electrocatalyst exhibited tolerance to methanol crossover effect. Based on its outstanding performance, this functionalized graphene electrocatalyst showed the promising prospect of a metal-free catalyst for fuel cell with much lower cost than currently used Pt/C catalyst.

Energy densification of animal waste lignocellulose biomass and raw biomass

The need to reduce carbon emissions has encouraged more research into use of biomass energy in place of coal. Biomass is carbon neutral; its use can therefore lower net emissions. Biomass can be upgraded to a fuel similar to coal by torrefaction. Different biomass have been torrefied but there is limited research in possible use of lignocellulose biomass from animal waste. This study aims to compare extent of energy densification of torrefied cow dung, corn cob and pine wood. They were dried, ground and sieved. Proximate and ultimate analysis was conducted. The samples were then torrefied at 200, 250 and 300 °C at 10 °C/min for 40 min. The resulting biochar were characterized using mass yield, higher heating value, energy yield and density. Biochar obtained at 250 °C were analyzed for elemental composition. Results were compared to Anglo bituminous coal and other torrefied biomass in literature. Corn cob and pine wood reached a maximum of 25.98 MJ/kg and 20.90 MJ/kg in heating value respectively whilst cow dung only increased to a maximum of 18.60 MJ/kg. Increase in heating value for corn cob was attributed to reduction in oxygen due to release of volatiles as well as water. This lowered the O/C ratio thereby densifying the fuel. The O/C and H/C ratio for corncob and wood moved towards that of bituminous coal unlike that of cow dung. Cow dung had a high inorganic composition so its heating value could not be upgraded as much as the other 2 biomass. Its use as a torrefaction raw material was therefore discouraged.

Driver detection of water quality trends in three large European river basins

This study analyses how indicators of water quality (thirteen physico-chemical variables) and drivers of change (i.e., monthly aggregated air temperature and streamflow, population density, and percentage of agricultural land use) coevolve in three large European river basins (i.e., Adige, Ebro, Sava) with different climatic, soil and water use conditions. Spearman rank correlation, Principal Component Analysis, and Mann-Kendall trend tests were applied to long-term time series of water quality data during the period 1990–2015 in order to investigate the relationships between water quality parameters and the main factors controlling them. Results show that air temperature, considered as a proxy of climatic change, has a significant impact, in particular in the Adige and Ebro: positive trends of water temperature and negative of dissolved oxygen are correlated with upward trends of air temperatures. The aquatic ecosystems of these rivers are, therefore, experiencing a reduction in oxygen, which may exacerbate in the future given the projected further increase in temperature. Furthermore, monthly streamflow has been shown to reduce in the Ebro, thereby reducing the beneficial effect of dilution, which appears evident from the observed upward patterns of chloride concentrations and electrical conductivity. Upward trends of chloride and biological oxygen demand in the Adige and Sava, and of phosphate in the Adige appears to be related to increasing human population density, whereas phosphates in the Sava and biological oxygen demand in the Ebro are highly correlated with agricultural land use, considered as a proxy of the impact of agricultural practises.The present study shows the complex relationships between drivers and observed changes in water quality parameters. Such analysis can represent, complementary to a deep knowledge of the investigated systems, a reliable tool for decision makers in river basin planning by providing an overview of the potential impacts on the aquatic ecosystem of the three basins.

Effects of V doping on magnetic and optical properties of oxygen-deficient In2O3 thin films

The scope of the work was to study structural, optical and magnetic behaviors of vanadium (V) doped indium oxide thin films prepared by thermal evaporation. Thin films of vanadium doped oxygen deficient In2O3 were deposited on sapphire, corning glass and Si(100) substrates. EDAX analysis revealed a great reduction in oxygen was happen during evaporation and oxygen deficient undoped and V doped In2O3 thin films were formed. XRD characterization suggested that the present In2O3 portion was in the amorphous state and the observed crystalline peaks were indexed as tetragonal metallic indium. The undoped In2O3 had the lowest transmittance and the transmittance increased with increasing V doping. The optical band gap and refractive index values decreased with increasing V doping. The dependence of magnetization on magnetic field for V doped In2O3 thin films were studied at 300K and 5K. All the samples exhibited soft ferromagnetic behaviour. The parameters of the hysteresis loop were extracted. The achieved results may find usage in magneto-optical applications.

Luminescence characteristics of some common polyester fabrics: Application to emergency dosimetry

A set of garment polyester-mix fabrics was tested for their potential suitability as surrogate dosimetry materials using optically and thermally stimulated luminescence techniques. A strong native blue-stimulated optically stimulated luminescence and thermoluminescence signal was observed with unirradiated samples, but this could be avoided by measurement of infra-red stimulated luminescence, and a sample of blue polyester-cotton mix fabric exhibited particularly high sensitivity to radiation dose. However, near complete fading at room temperature within several hours and rapid bleaching of the signal when exposed to daylight limit the deployment of this mode of measurement. The fading behaviour is critically dependent on the atmosphere in which the material is measured and on the storage conditions, where a reduction in oxygen significantly reduces the rate of fading. A cathodoluminescence study of the samples performed in a scanning electron microscope revealed complex emission spectra obtained with spatially integrated measurements and, in one fabric examined in more detail, the spatially resolved emission was found to vary in intensity and wavelength within the polyester fibre filaments which is likely to be associated with differences in crystallinity.

Renin-Angiotensin-Aldosterone System Is Not Involved in the Arterial Stiffening Induced by Acute and Prolonged Exposure to High Altitude.

URL: https://www.clinicaltrialsregister.eu/. Unique identifier: 2008-000540-14.

Research on the release of gases during the bituminous coal combustion under low oxygen atmosphere by TG–FTIR

The recirculation of boiler tail gas with a low oxygen concentration can reduce NOx emissions. Experiments on bitumite combustion were carried out using simultaneous TG/FTIR dynamic runs with different atmospheric compositions, 2%, 6%, 10%, and 12% O2. Reducing oxygen concentrations led to the burnout temperature shifting to higher temperature and coal combustion becoming more challenging. The reducing gas (CO, CH4) emissions were abundant between 330 °C and 690 °C. However, along with the reduction in oxygen, CH4 intensity increased, while the CO precipitation peak lowered. Kinetic parameters were defined using the Coats-Redfern model. According to the data obtained, bitumite combustion activation energy increased as oxygen concentration increased.

A comprehensive review of the bioenergetics of fatty acid and glucose metabolism in the healthy and failing heart in nondiabetic condition.

The function of the heart is defined by its ability to deliver adequate cardiac output to meet the requirements of the body both at rest and with exertion. To fill this role, the heart demonstrates an impressive capacity to tightly regulate energy generation and consumption. Energy production and transfer within cardiac myocytes primarily relies on the process of oxidative phosphorylation. In the failing heart, there is an imbalance between the work of the cardiac system and the energy required to generate this work. This presence of this mismatch has given rise to the concept known as the energy starvation theory. This concept encapsulates observations such as perturbed substrate consumption, insufficient energy transfer and ingestion, reduced substrate and oxygen availability, and diminished energy production in the failing heart. Diminished available cellular energy may further result from a reduction in the biosynthesis of mitochondria and their protein synthesis and from global cellular architectural disarray. In essence, the energy starvation theory posits that cardiac pump function declines due to a reduction in oxygen and substrate availability, and thus leads to a total body starvation of systemic energy. This novel cognitive framework has led to encouraging new directions in a "metabolic therapeutic approach" for the failing heart.

A study on structural stability of bismuth titanate with lanthanum doping for improved ferroelectric properties

Bismuth titanate $$(\hbox {Bi}_{4}\hbox {Ti}_{3}\hbox {O}_{12})$$ with different lanthanum (La) concentrations (0.25, 0.50, 0.75 and 1.0 mol%) was successfully prepared via soft combustion route. It was found that the change of diffraction peaks shown by X-ray diffraction is attributed to the doping effect in $$\hbox {Bi}_{4}\hbox {Ti}_{3}\hbox {O}_{12}$$ . This was also supported by the presence of additional peak that corresponds to La in the range of 800–860 eV, proved by X-ray photoelectron spectroscopy. In addition, the enlarged region of Bi 4f, Bi 4d, Ti 2p, La 3d and O 1s of doping sample was clearly seen after deconvolution. Based on binding energy position, it can be unambiguously stated that the Ti ions in the tetravalent state are surrounded by the perovskite layer of $$\hbox {Bi}_{4}\hbox {Ti}_{3}\hbox {O}_{12}$$ , which may also imply the formation of oxygen vacancies in the vicinity of the $$\hbox {Bi}_{2}\hbox {O}_{2}$$ layer. In comparison with $$\hbox {Bi}_{4}\hbox {Ti}_{3}\hbox {O}_{12}$$ , the green emission intensity was abruptly decreased with La doping. This indicates that La doping suppresses the formation of oxygen vacancies by stabilizing the adjacent oxide ions. Thus, the improved polarization shown by ferroelectric hysteresis loop is associated with the reduction in oxygen and bismuth vacancies due to La doping.

Ultra-High Purity Hydrazine Delivery for Low Temperature Metal Nitride ALD

There is an emerging need for sub-400°C metal nitride deposition due to thermal sensitivity of new materials for logic and memory devices. University studies have shown hydrazine to be a viable precursor for low temperature ALD. A novel high-purity hydrazine delivery system has been developed in response to market need. Initial tests show significant reduction in oxygen in TiNx films using this system.

RF assisted Glow Discharge Condition experiment for SST-1 Tokamak

Impurity control reduces the radiation loss from plasma and hence enhances the plasma operation. Oxygen and water vapors are the most common impurities in tokamak devices. Water vapour can be reduced with extensive baking while in order to have a significant reduction in oxygen it is necessary to use glow discharge condition (GDC). RF assisted glow discharge cleaning system will be implemented to remove low z impurities at PFC installed SST-1 vacuum vessel. A RF assisted Glow discharge conditioning is studied at laboratory to find the optimum operating parameters in a view to implement at SST-1 tokamak. Helium is used as a fuel gas in the present experiment. It is observed that the ultimate impurity level is reduced significantly below to the accepted level for plasma operation after RF assisted GDC. The experimental findings of RF assisted Glow discharge conditioning is discussed in details in this paper.

Neurodevelopmental Effects of Undernutrition and Placental Underperfusion in Fetal Growth Restriction Rabbit Models

Introduction: Chronic reduction of oxygen and nutrient delivery to the fetus has been related to neurodevelopmental problems. Placental underperfusion induces a significant reduction in oxygen and nutrient delivery, whereas maternal undernutrition causes mainly nutrient deficiency. A comparison of the neurodevelopmental effects of both situations in pregnant rabbits was performed. Materials and Methods: The placental underperfusion model was induced after uteroplacental vessel ligation at 25 days of pregnancy. The undernutrition model was induced after a reduction of 70% of the basal maternal intake at 22 days of pregnancy. Neurobehavioral tests were applied in the derived offspring at the neonatal period and over the long term. Structural brain differences were evaluated by brain networks obtained from diffusion magnetic resonance imaging. Results: Birth weight was significantly lower in both cases. However, stillbirth was only increased in the placental underperfusion model. Cases from both models presented poorer neurobehavioral performance and network infrastructure, being more pronounced in the placental underperfusion model. Discussion: Prenatal insults during the last third of gestation resulted in functional and structural disturbances. The degree of neurodevelopmental impairment and its association with structural brain reorganization seemed to be related to the type of the prenatal insult, showing stronger effects in the placental underperfusion model.

Sensory systems: Smelling trouble.

It is not known how mammals sense potentially life-threatening reductions in oxygen in the ambient air, but a novel mechanism has been found in mice that involves a novel subpopulation of olfactory sensory neurons that express the soluble guanylate cyclase GUCY1β2.

Eastern Baltic cod recruitment revisited—dynamics and impacting factors

The Eastern Baltic cod abundance started rapidly to increase in the mid-2000s as evidenced by analytical stock assessments, due to increased recruitment and declining fishing mortality. Since 2014, the analytical stock assessment is not available, leaving the present stock status unclear and casting doubts about the magnitude of the recent increase in recruitment. Earlier studies identified main factors impacting on cod reproductive success to be related to the loss of two out of three spawning areas in the 1980s caused by lack of major Baltic inflows with a concurrent reduction in salinity and oxygen. Other important factors include prey availability for first-feeding larvae, egg predation by sprat and herring and cannibalism on juveniles, all in one way or the other related to the prevailing hydrographic conditions. These factors cannot explain increased reproductive success in the last decade, as the period was characterized by an absence of large-scale Baltic inflows since 2003 and persistent anoxic conditions in the bottom water of the deep Baltic basins. This questions the perception of the increased recruitment in later years and challenges our present understanding of cod recruitment dynamics in the Baltic Sea. In this contribution, we review evidence from the recent literature supplemented by information from latest research cruises to elucidate whether cod reproductive success indeed has increased during the last decade, and we suggest the key processes responsible for the recent dynamics in cod recruitment and outline directions for future research.

Linear and nonlinear optical investigations of nano-scale Si-doped ZnO thin films: spectroscopic approach

Pure and Si-doped ZnO (SZO) thin films at different concentration of Si (1.9 and 2.4 wt%) were deposited on highly cleaned glass substrate by radio frequency (DC/RF) magnetron sputtering. The morphological and structural investigations have been performed by atomic force electron microscope (AFM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy was employed to study the composition and the change in the chemical state of Si-doped ZnO thin films. The optical observations like transmittance, energy band gap, extinction coefficient, refractive index, dielectric loss of pure and Si-doped ZnO thin films have been calculated. The linear optical susceptibility, nonlinear refractive index, and nonlinear optical susceptibility were also studied by the spectroscopic approach rather than conventional Z-scan method. The energy gap of Si-doped ZnO thin films was found to increase as compared to pure ZnO thin films. The crystallinity of the ZnO thin films was effected by the Si doping. The O1s spectra in pure and Si-doped ZnO revealed the bound between O−2 and Zn+2 ions and reduction in the surface oxygen with the Si doping. The chemical state analysis of Si 2p showed the conversation of Si to SiOx and SiO2. The increase in the first-order linear optical susceptibility χ (1) and third-order nonlinear optical susceptibility χ (3) was observed with the Si doping. The nonlinear studies gave some details about the applications of metal oxides in nonlinear optical devices. In short, this study showed that Si doping through sputtering has effected on the structural, surface and optical properties of ZnO thin films which could be quite useful for advanced applications such as metal-oxide-based optical devices.

Impact of semidiurnal tidal variability during SSWs on the mean state of the ionosphere and thermosphere

AbstractObservations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites reveal a global reduction in the zonal and diurnal mean F region peak electron density (NmF2) during sudden stratosphere warmings (SSWs). The present study investigates the source of the global NmF2 decrease by performing numerical experiments with the National Center for Atmospheric Research (NCAR) thermosphere‐ionosphere‐electrodynamics general circulation model. The simulations reveal that the NmF2 reduction coincides with a depletion of thermospheric [O]/[N2], indicating that the NmF2 depletion is related to changes in thermospheric composition during SSWs. Numerical experiments further illustrate that the short‐term (∼10 day) enhancement of the migrating semidiurnal solar tide (SW2) during SSWs is the source of the variability in thermospheric composition. In particular, the enhancement of the SW2 during SSWs alters the lower thermosphere zonal mean circulation, leading to a reduction in atomic oxygen in the lower thermosphere. The atomic oxygen reduction propagates into the upper thermosphere through molecular diffusion, leading to a decrease in [O]/[N2] throughout the low‐ to middle‐latitude thermosphere. It is anticipated that the effects of the SW2 on the ionosphere and thermosphere investigated herein will be modulated by SSW related enhancements of the migrating semidiurnal lunar tide (M2). The magnitude of the combined impact of the SW2 and M2 on the ionosphere‐thermosphere mean state will depend on the relative phasing of the solar and lunar tides. The results demonstrate that in addition to modulating the low‐latitude electrodynamics, tidal variability during SSWs can significantly impact the mean state of the ionosphere and thermosphere.

Onset and progression of soot in high-pressure n-dodecane sprays under diesel engine conditions

Soot onset in n -dodecane sprays is investigated both experimentally, by means of high-speed imaging data from the Sandia spray combustion vessel, and numerically, using the conditional moment closure combustion model and an integrated two-equation soot model in a Reynolds-averaged Navier–Stokes framework. Five operating conditions representative of modern diesel engines are studied at constant density (22.8 kg/m3) with variations in ambient oxygen concentration and temperature. The reference case at 15% O2 and 900 K is compared with measurements in terms of the evolving soot mass distribution and spatiotemporal distributions of formaldehyde and polycyclic aromatic hydrocarbons obtained by 355-nm laser-induced fluorescence (polycyclic aromatic hydrocarbons represented by C2H2 in simulation) and soot optical thickness ( KL) signal obtained by diffused back-illumination extinction imaging. All operating points are validated in terms of ignition delay and lift-off length, soot onset time and location, soot mass evolution, and peak location. Measurements show that time lag between ignition and soot onset is considerably increased by a reduction in ambient oxygen or temperature. The trend of this time lag is captured very well by the simulations, as is the evolving axial distribution of soot, despite the simple soot model employed. Building on the good agreement between spatiotemporal distributions in experiment and simulation, further results from the latter are extracted to provide insight into relevant processes. The advancing soot tip lags behind the fuel–vapor spray tip due to soot oxidation. Tracking the Lagrangian time history of notional fluid particles from the soot onset location back to the injector orifice reveals that their trajectories evolve along rich conditions (φ > 1.5) throughout the entire path. Overall, novel insights obtained from experiments with respect to soot and soot precursor evolutions are complemented by simulations using the integrated conditional moment closure/soot modeling approach, showing encouraging results for prediction and understanding of transient soot processes in high-pressure diesel sprays.

Antioxidant activity and superoxide anion radical interaction with 2-(ferrocenylmethylamino) benzonitrile and 3-(ferrocenylmethylamino) benzonitrile

Cyclic voltammetry was used to explore the interaction of (ferrocenylmethylamino) benzonitrile (FMAB) with superoxide anion radical (\({\text{O}}_{2}^{. - }\)), electrochemically generated by the reduction in commercial molecular oxygen in acetonitrile. The difference in the electrochemical behavior of \({\text{O}}_{2}^{. - }\) in the absence and presence of FMAB, including shifts in peak potential and decrease in anodic peak current, was successfully investigated for the determination of interaction parameters such as the binding constant, ratio of binding constants, binding free energy and mode of interaction. The anodic peak potential shifts and the magnitude of binding free energy ΔG suggest the electrostatic interaction of \({\text{O}}_{2}^{. - }\) with FMAB as the dominant mode, whereas the negative sign of ΔG indicates the spontaneity of the interaction. The antioxidant activity of FMAB derivatives was also evaluated using spectrophotometrical and electrochemical techniques. The spectrophotometrical assays were carried out using 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), while the electrochemical assays were determined by measuring the oxidation peak current of \({\text{O}}_{2}^{. - }\). The activity was found to be highest for 3FMAB in both DPPH and \({\text{O}}_{2}^{. - }\) radicals scavenging methods (0.0183) and (0.0090 mg/mL), respectively, which is equal to half the antioxidant activity of standard antioxidant ascorbic acid (0.0117) and (0.0041 mg/mL).

The effect of environmental hypercapnia and size on nitrite toxicity in the striped catfish (Pangasianodon hypophthalmus)

Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl− for uptake at the branchial HCO3−/Cl− exchanger, causing a drastic reduction in the blood oxygen carrying capacity through the formation of methaemoglobin and nitrosylhaemoglobin. Environmental hypercapnia induces a respiratory acidosis where the branchial HCO3−/Cl− exchange activity is reduced in order to retain HCO3− for pH recovery, which should lead to a reduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in the dorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasma ions and acid-base status during exposure to 0.9mM nitrite alone and in combination with acute and 48h acclimated hypercapnia over a period of 72h. Nitrite uptake was initially reduced during the hypercapnia-induced acidosis, but after pH recovery the situation was reversed, resulting in higher plasma nitrite concentrations and lower functional haemoglobin levels that eventually caused mortality. This suggests that branchial HCO3−/Cl− exchange activity is reduced only during the initial acid-base compensation, but subsequently increases with the greater availability of internal HCO3− counter-ions as pH is compensated. The data further suggest that branchial Na+/H+ exchange plays a significant role in the initial phase of acid-base compensation. Overall, longer term environmental hypercapnia does not protect against nitrite uptake in P. hypophthalmus, but instead enhances it. In addition, we observed a significant size effect in nitrite accumulation, where large fish attained plasma [nitrite] above the ambient concentration, while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], and haemoglobin concentrations, revealing greater capacity for detoxifying nitrite by oxidising it to nitrate.