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Oxygen kinetics

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https://www.readbyqxmd.com/read/28937947/wastewater-treatment-by-means-of-thermophilic-aerobic-membrane-reactors-respirometric-tests-and-numerical-models-for-determination-of-stoichiometric-kinetic-parameters
#1
Maria Cristina Collivignarelli, Giorgio Bertanza, Alessandro Abbà, Vincenzo Torretta, Ioannis Anastasios Katsoyiannis
The present work considers the pollution abatement of wastewaters, the efficiency of which is depending on stringent verification of the performance of wastewater treatment plants. This is very important especially given that eExisting wastewater/aqueous waste treatment plants often need to be upgraded in order to improve their performance. The satisfactory operation of biological treatment plants requires appropriate monitoring, and respirometric techniques are needed to determine the kinetic parameters that regulate biological processes...
September 22, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28937637/adsorption-mechanisms-of-dodecylbenzene-sulfonic-acid-by-corn-straw-and-poplar-leaf-biochars
#2
Nan Zhao, Xixiang Yang, Jing Zhang, Ling Zhu, Yizhong Lv
Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer-Emmett-Teller N₂ surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA)...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28936989/diffusion-of-interstitials-in-metallic-systems-illustration-of-a-complex-study-case-aluminum
#3
Matthieu David, Damien Connetable
While diffusion mechanisms of interstitial elements in fcc systems are generally well-known, especially in the case of H atoms, we show in this work that even in the case of a simple metallic system (aluminum), the diffusion of interstitials exhibits a wide variety of paths and mechanisms that depend on the specie. We used an approach based on first-principles calculations associated with kinetic Monte-Carlo simulations and a multi-state diffusion formalism to compute the diffusion coefficients of five interstitial elements: hydrogen, boron, carbon, nitrogen and oxygen...
September 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28936518/microscopic-time-resolved-imaging-of-singlet-oxygen-by-delayed-fluorescence-in-living-cells
#4
Marek Scholz, Roman Dědic, Jan Hála
Singlet oxygen is a highly reactive species which is involved in a number of processes, including photodynamic therapy of cancer. Its very weak near-infrared emission makes imaging of singlet oxygen in biological systems a long-term challenge. We address this challenge by introducing Singlet Oxygen Feedback Delayed Fluorescence (SOFDF) as a novel modality for semi-direct microscopic time-resolved wide-field imaging of singlet oxygen in biological systems. SOFDF has been investigated in individual fibroblast cells incubated with a well-known photosensitizer aluminium phthalocyanine tetrasulfonate...
September 22, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28935942/oxygen-evolution-reaction-dynamics-monitored-by-an-individual-nanosheet-based-electronic-circuit
#5
Peiyao Wang, Mengyu Yan, Jiashen Meng, Gengping Jiang, Longbing Qu, Xuelei Pan, Jefferson Zhe Liu, Liqiang Mai
The oxygen evolution reaction involves complex interplay among electrolyte, solid catalyst, and gas-phase and liquid-phase reactants and products. Monitoring catalysis interfaces between catalyst and electrolyte can provide valuable insights into catalytic ability. But it is a challenging task due to the additive solid supports in traditional measurement. Here we design a nanodevice platform and combine on-chip electrochemical impedance spectroscopy measurement, temporary I-V measurement of an individual nanosheet, and molecular dynamic calculations to provide a direct way for nanoscale catalytic diagnosis...
September 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28934911/characterization-and-phenol-adsorption-performance-of-activated-carbon-prepared-from-tea-residue-by-naoh-activation
#6
Jun Tao, Peili Huo, Zongheng Fu, Jin Zhang, Zhen Yang, Dengfeng Zhang
The preparation of activated carbon (AC) using tea residue as precursor was fully addressed in this work. The preparation process mainly incorporated two-step pyrolysis and activation using NaOH. The influence of activation temperature ranging between 500 and 700 (o)C on the properties of the obtained AC sample was investigated. The physicochemical properties of the prepared AC sample were characterized using N2 adsorption/desorption, scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)...
September 22, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28933825/the-surface-chemistry-of-perovskite-type-electrodes-during-high-temperature-co2-electrolysis-investigated-by-operando-photoelectron-spectroscopy
#7
Alexander Karl Opitz, Andreas Nenning, Christoph Rameshan, Markus Kubicek, Thomas Götsch, Raoul Blume, Michael Hävecker, Axel Knop-Gericke, Gunther Rupprechter, Bernhard Klötzer, Juergen Fleig
Any substantial move of energy sources from fossil fuels to renewable resources requires large scale storage of excess energy, for example via power to fuel processes. In this respect electrochemical reduction of CO2 may become very important, since it offers a method of sustainable CO production, which is a crucial prerequisite for synthesis of sustainable fuels. Carbon dioxide reduction in solid oxide electrolysis cells (SOECs) is particularly promising owing to the high operating temperature, which leads to both improved thermodynamics and fast kinetics...
September 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28933817/unusual-spinel-to-layered-transformation-in-limn2o4-cathode-explained-by-electrochemical-thermal-stability-investigation
#8
Liubin Ben, Hailong Yu, Bin Chen, Yuyang Chen, Yue Gong, Xinan Yang, Lin Gu, Xuejie Huang
Distorted surface regions (5-6 nm) with an unusual layered-like structure on LiMn2O4 cathode material were directly observed after it was cycled (3-4.9 V), indicating a possible spinel-to-layered structural transformation. Formation of these distorted regions severely degrades LiMn2O4 cathode capacity. Getting a better understanding of the exact crystal structure of the distorted regions, the structural transformation pathways and the origins of the distortion is made difficult by the regions' nanoscopic size...
September 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28933550/boron-heteroatom-addition-reactions-via-borylative-heterocyclization-oxyboration-aminoboration-and-thioboration
#9
Adena Issaian, Kim N Tu, Suzanne A Blum
Organoboron compounds and heterocycles are powerful building blocks and precursors for organic synthesis, including for drug discovery and agrochemical and material synthesis. The common strategy for the synthesis of borylated heterocycles involves two separate synthetic steps: first, synthesis of the heterocyclic core, and second, borylation of the core through established methods such as transition-metal-catalyzed C-H or C-X activation/borylation or lithiation/borylation. In this Account, we describe our laboratory's development of borylative heterocyclization reactions that access the heterocyclic core and install boron in one synthetic step...
September 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28933544/conformational-dynamics-and-exchange-kinetics-of-n-formyl-and-n-acetyl-groups-substituting-3-amino-3-6-dideoxy-%C3%AE-d-galactopyranose-a-sugar-found-in-bacterial-o-antigen-polysaccharides
#10
Olof Engström, Hani Mobarak, Jonas Ståhle, Göran Widmalm
Three dimensional shape and conformation of carbohydrates are important factors in molecular recognition events and the N-acetyl group of a monosaccharide residue can function as a conformational gatekeeper whereby it influences the overall shape of the oligosaccharide. NMR spectroscopy and quantum mechanics (QM) calculations are used herein to investigate both the conformational preferences and the dynamic behavior of N-acetyl and N-formyl substituents of 3-amino-3,6-dideoxy-α-D-galactopyranose, a sugar and substitution patterns found in bacterial O-antigen polysaccharides...
September 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28925951/transparent-pullulan-mica-nanocomposite-coatings-with-outstanding-oxygen-barrier-properties
#11
Ilke Uysal Unalan, Derya Boyacı, Silvia Trabattoni, Silvia Tavazzi, Stefano Farris
This study presents a new bionanocomposite coating on poly(ethylene terephthalate) (PET) made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α), at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite). A very small amount of mica (0.02 wt %, which is ϕ ≈ 0.00008) in pullulan coatings dramatically improved the oxygen barrier performance of the nanocomposite films under dry conditions, however, this performance was partly lost as the environmental relative humidity (RH) increased...
September 19, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28925377/applied-upper-airway-resistance-instantly-affects-breath-components-a-unique-insight-into-pulmonary-medicine
#12
Pritam Sukul, Jochen Schubert, Svend Kamysek, Phillip Trefz, Wolfram Miekisch
Respiratory parameters such as flow or rate have complex effects onto exhalation of volatile substances and can hamper clinical interpretation of breath biomarkers. We investigated effects of progressively applied upper-airway resistances onto exhalation of volatile organic compounds (VOCs) in healthy humans. We performed real-time mass-spectrometric determination of breath volatiles in 50 subjects with parallel non-invasive hemodynamic monitoring, breath-resolved spirometry and capnometry during controlled tidal breathing (12 breaths/min)...
September 19, 2017: Journal of Breath Research
https://www.readbyqxmd.com/read/28924618/optical-studies-of-the-solution-phase-reduction-and-stabilization-of-indigo-tetrasulfonate-in-polyelectrolyte-complexes
#13
Becca Hoene, Dion Rivera
Ultraviolet-visible (UV-vis) and fluorescence spectroscopy have been used to characterize the polyelectrolyte complexes (PECs) formed when potassium indigo tetrasulfonate (ITS) interacts with poly diallydimethylammonium chloride (PDADMAC) through columbic attraction in the presence of the reducing agent sodium bisulfite, NaHSO3. The PDADMAC facilitates both the reduction of the ITS and the stabilization of the reduced state of the ITS in an atmospheric oxygen environment. Dilutions of the dye solution show that the PEC is stable to dilutions of at least 1 to 1000...
September 2017: Heliyon
https://www.readbyqxmd.com/read/28923730/kinetics-analysis-of-interfacial-electron-transfer-processes-in-goethite-suspensions-systems
#14
Jianzhong Ma, Chengzhu Zhu, Jun Lu, Bin Ouyang, Qiaoqin Xie, Haibo Liu, Shuchuan Peng, Tianhu Chen
The photochemical behavior of goethite has been one of the most important topics in the field of environmental science due to it plays a significant role in the removal and transformation process of numerous pollutants. However, the interfacial electron transfer process of goethite is not clear. Using a nanosecond laser flash photolysis spectrometer, we report the transient spectroscopic observations of interfacial electron-transfer reactions in goethite dispersion under UV irradiation. Excitation of goethite generated conduction-band electron (ecb(-)) and hole (h(+))...
September 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28921983/the-first-state-in-the-catalytic-cycle-of-the-water-oxidizing-enzyme-identification-of-a-water-derived-%C3%AE-hydroxo-bridge
#15
Thomas Lohmiller, Vera Krewald, Arezki Sedoud, A William Rutherford, Frank Neese, Wolfgang Lubitz, Dimitrios A Pantazis, Nicholas Cox
Nature's water splitting catalyst, an oxygen-bridged tetra-manganese calcium (Mn4O5Ca) complex, sequentially activates two substrate water molecules generating molecular O2. Its reaction cycle is composed of five intermediate (Si) states, where the index i indicates the number of oxidizing equivalents stored by the cofactor. After formation of the S4 state, the product dioxygen is released and the cofactor returns to its lowest oxidation state, S0. Membrane-inlet mass spectrometry measurements suggest that at least one substrate is bound throughout the catalytic cycle, as the rate of (18)O-labeled water incorporation into the product O2 is slow, on a millisecond to second timescale depending on the S state...
September 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28919863/oxygen-uptake-kinetics-is-slower-in-swimming-than-arm-cranking-and-cycling-during-heavy-intensity
#16
Ana Sousa, Fabio Borrani, Ferran A Rodríguez, Grégoire P Millet
Oxygen uptake ([Formula: see text]) kinetics has been reported to be influenced by the activity mode. However, only few studies have compared [Formula: see text]O2 kinetics between activities in the same subjects in which they were equally trained. Therefore, this study compared the [Formula: see text]O2 kinetics response to swimming, arm cranking, and cycling within the same group of subjects within the heavy exercise intensity domain. Ten trained male triathletes (age 23.2 ± 4.5 years; height 180.8 ± 8...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28919528/modification-of-wool-protein-fiber-with-plasma-and-dendrimer-effects-on-dyeing-with-cochineal
#17
Toktam Sajed, Aminoddin Haji, Mohammad Khajeh Mehrizi, Majid Nasiri Boroumand
In this study, plasma treatment and a poly(propylene imine) dendrimer were employed to improve the dyeability of wool fibers with cochineal natural dye. FESEM, EDX, AFM and FTIR techniques were employed to investigate the effects of these treatments on chemical and physical properties of wool fibers. The etching of surface layer of wool fibers and increased roughness after plasma treatment was confirmed by FESEM and AFM images. EDX and FTIR analyses confirmed the creation of oxygen-containing groups and attachment of dendrimer molecules on wool fibers after plasma and dendrimer treatments respectively...
September 14, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28919428/metal-mediated-oxidation-of-fluoroquinolone-antibiotics-in-water-a-review-on-kinetics-transformation-products-and-toxicity-assessment
#18
Mingbao Feng, Zunyao Wang, Dionysios D Dionysiou, Virender K Sharma
Fluoroquinolones (FQs) are among the most potent antimicrobial agents, which have seen their increasing use as human and veterinary medicines to control bacterial infections. FQs have been extensively found in surface water and municipal wastewaters, which has raised great concerns due to their negative impacts to humans and ecological health. It is of utmost importance that FQs are treated before their release into the environment. This paper reviews oxidative removal of FQs using reactive oxygen (O3 and OH), sulfate radicals (SO4(-)), and high-valent transition metal (Mn(VII) and Fe(VI)) species...
August 30, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28919166/kinetic-analysis-of-oxygen-dynamics-under-a-variable-work-rate
#19
Alexander Artiga Gonzalez, Raphael Bertschinger, Fabian Brosda, Thorsten Dahmen, Patrick Thumm, Dietmar Saupe
Measurements of oxygen uptake are central to methods for the assessment of physical fitness and endurance capabilities in athletes. Two important parameters extracted from such data of incremental exercise tests are the maximal oxygen uptake and the critical power. A commonly accepted model of the dynamics of oxygen uptake during exercise at a constant work rate comprises a constant baseline oxygen uptake, an exponential fast component, and another exponential slow component for heavy and severe work rates...
September 14, 2017: Human Movement Science
https://www.readbyqxmd.com/read/28918632/analysis-and-sensory-evaluation-of-the-stereoisomers-of-a-homologous-series-c5-c10-of-4-mercapto-2-alkanols
#20
Svenja Nörenberg, Christiane Kiske, Bastian Reichardt, Verena Andelfinger, Anne Pfeiffer, Franziska Schmidts, Wolfgang Eisenreich, Karl-Heinz Engel
A homologous series of 4-mercapto-2-alkanols (C5-C10) was used to investigate the impact of the stereochemistry on the sensory properties of a class of naturally occurring polyfunctional thiols having a 1,3-oxygen-sulfur functionality. Stereoisomers were obtained via syntheses of racemic mixtures and subsequent lipase-catalyzed kinetic resolutions. Analytical separations of the stereoisomers were achieved by capillary gas chromatography (GC) using chiral stationary phases. The absolute configurations were assigned via NMR analysis...
September 17, 2017: Journal of Agricultural and Food Chemistry
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