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Oxygen kinetics

Qin Xiang, Yuping Liu, Xuefeng Zou, Bingbing Hu, Yujie Qiang, Danmei Yu, Wei Yin, Changguo Chen
In this work, g-C3N4@GO gel-like hybrid is obtained by assembling intentionally exfoliated g-C3N4 sheets on graphene oxide (GO) sheets under a hydrothermal condition. A specific N-doping process is firstly designed by heating the g-C3N4@GO interlaced hybrid in vacuum to form nitrogen-doped graphene nanosheets (NGS) with high level of pyridinic-N (56.0%) and edge-rich defect structure. The prepared NGS exhibited a great electrocatalysis for oxygen reduction reaction (ORR) in terms of the activity, durability, methanol tolerance, and the reaction kinetics...
March 16, 2018: ACS Applied Materials & Interfaces
Peter L Cummins, Babu Kannappan, Jill E Gready
The ubiquitous enzyme Ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBisCO) fixes atmospheric carbon dioxide within the Calvin-Benson cycle that is utilized by most photosynthetic organisms. Despite this central role, RuBisCO's efficiency surprisingly struggles, with both a very slow turnover rate to products and also impaired substrate specificity, features that have long been an enigma as it would be assumed that its efficiency was under strong evolutionary pressure. RuBisCO's substrate specificity is compromised as it catalyzes a side-fixation reaction with atmospheric oxygen; empirical kinetic results show a trend to tradeoff between relative specificity and low catalytic turnover rate...
2018: Frontiers in Plant Science
Andy A Thomas, Andrew F Zahrt, Connor P Delaney, Scott E Denmark
The Suzuki-Miyaura reaction is the most practiced palladium-catalyzed, cross-coupling reaction because of its broad applicability, low toxicity of the metal (B), and the wide variety of commercially available boron substrates. A wide variety of boronic acids and esters, each with different properties, have been developed for this process. Despite the popularity of the Suzuki-Miyaura reaction, the precise manner in which the organic fragment is transferred from boron to palladium has remained elusive for these reagents...
March 15, 2018: Journal of the American Chemical Society
Robert T Mankowski, Victor M Niemeijer, Jasper P Jansen, Lotte Spraakman, Henk J Stam, Stephan F E Praet
Purpose: It is still equivocal whether oxygen uptake recovery kinetics are limited by oxygen delivery and can be improved by supplementary oxygen. The present study aimed to investigate whether measurements of muscle and pulmonary oxygen uptake kinetics can be used to assess oxygen delivery limitations in healthy subjects. Methods: Sixteen healthy young adults performed three sub-maximal exercise tests (6 min at 40% Wmax ) under hypoxic (14%O2 ), normoxic (21%O2 ) and hyperoxic (35%O2 ) conditions on separate days in randomized order...
June 2017: Journal of Exercise Science and Fitness
Juan Pan, Minakshi Bhardwaj, Bo Zhang, Wei-Chen Chang, Christopher Lewis Schardl, Carsten Krebs, Robert B Grossman, J Martin Bollinger
The core of the loline family of insecticidal alkaloids is the bicyclic pyrrolizidine unit with an additional strained ether bridge between carbons 2 and 7. Previously reported genetic and in vivo biochemical analyses showed that the presumptive iron- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, LolO, is required for installation of the ether bridge upon the pathway intermediate, 1- exo-acetamidopyrrolizidine (AcAP). Here we show that LolO is, in fact, solely responsible for this biosynthetic four-electron oxidation...
March 14, 2018: Biochemistry
Bo You, Yujie Sun
Electrocatalytic water splitting driven by renewable energy input to produce clean H2 has been widely viewed as a promising strategy of the future energy portfolio. Currently, the state-of-the-art electrocatalysts for water splitting in acidic solutions are IrO2 or RuO2 for the O2 evolution reaction (OER) and Pt for the H2 evolution reaction (HER). Realization of large-scale H2 production from water splitting requires competent nonprecious electrocatalysts. Despite the advances of decades in this field, several challenges still exist and need to be overcome: (1) Most efforts in the design of nonprecious electrocatalysts have focused on developing HER catalysts for acidic conditions but OER catalysts for alkaline conditions owing to their thermodynamic convenience, potentially resulting in incompatible integration of the two types of catalysts and thus inferior overall performance...
March 14, 2018: Accounts of Chemical Research
Daniele Missio, Natália Picolli Folchini, Fabio Gallas Leivas, Cecília Isabel Inês Urquiza Machado Pavin, Hirya Fernandes Pinto, Francielli Weber Santos Cibin, Daniela Dos Santos Brum
The aim of the present study was to evaluate the effects of Percoll volume on recovery rate, sperm quality, and embryo development kinetics in in vitro production of cattle embryos. Straws of conventional and sex-sorted semen were allocated to three different volumes of Percoll: 300 μL of each Percoll gradient (90%, 60%, and 30%), Control; 100 μL of each Percoll gradient, P100; and 200 μL of each Percoll gradient, P200. Sperm quality, fertilization rate, and embryo morpho-kinetic development using time lapse cinematography up to 48 h post-insemination were evaluated...
March 4, 2018: Animal Reproduction Science
Konrad Skotnicki, Julio Ramón De la Fuente, Alvaro Cañete, Eduardo Berrios, Krzysztof Bobrowski
The absorption-spectral and kinetic behavior of radical ions and neutral hydrogenated radicals of seven 3-styryl-quinoxalin-2(1 H)-one (3-SQ) derivatives, one without substituents in styryl moiety, four others with electron donating (R = -CH3 , -OCH3 , -N(CH3 )2) or electron withdrawing (R = -OCF3 ) substituents in para-position in benzene ring, and remaining two with double methoxy substituents (-OCH3 ), however, at different position (meta/para and ortho/meta) have been studied by UV-vis spectrophotometric pulse radiolysis in a neat acetonitrile saturated with argon (Ar) and oxygen (O2 ) and in 2-propanol saturated with Ar, at room temperature...
March 13, 2018: Journal of Physical Chemistry. B
Dhissanuvach Chaikhot, Matthew J D Taylor, Florentina J Hettinga
An awareness of sex differences in gait can be beneficial for detecting the early stages of gait abnormalities that may lead to pathology. The same may be true for wheelchair propulsion. The aim of this study was to determine the effect of sex on wheelchair biomechanics and mechanical efficiency in novice young able-bodied wheelchair propulsion. Thirty men and 30 women received 12  min of familiarisation training. Subsequently, they performed two 10-m propulsion tests to evaluate comfortable speed (CS). Additionally, they performed a 4-min submaximal propulsion test on a treadmill at CS, 125% and 145% of CS...
March 13, 2018: European Journal of Sport Science
Jonas J Neumeier, Matthias T Elm, Bjoern Luerßen, Jürgen Janek
To better understand the electrode kinetics of oxygen reduction and oxidation of gadolinia doped ceria (GDC), the electrochemical properties of platinum electrodes on GDC single crystals and polycrystalline samples were investigated with geometrically well-defined microelectrodes. For comparison measurements were also performed on polycrystalline samples using platinum interdigital electrodes in order to access the effect of the electrode geometry on the electrochemical properties. The transport properties were characterised using impedance spectroscopy, allowing to separate the transport processes of the electrode and the electrolyte...
March 13, 2018: Physical Chemistry Chemical Physics: PCCP
Laimonas Kelbauskas, Shashaanka P Ashili, Kristen B Lee, Haixin Zhu, Yanqing Tian, Deirdre R Meldrum
Functional and genomic heterogeneity of individual cells are central players in a broad spectrum of normal and disease states. Our knowledge about the role of cellular heterogeneity in tissue and organism function remains limited due to analytical challenges one encounters when performing single cell studies in the context of cell-cell interactions. Information based on bulk samples represents ensemble averages over populations of cells, while data generated from isolated single cells do not account for intercellular interactions...
March 12, 2018: Scientific Reports
Jianjun Zhou, Xionghui Ji, Xiaohui Zhou, Jialin Ren, Yaochi Liu
A novel magnetic bio-adsorbent (MCIA) was developed, characterized and tested for its Cd(II) removal from aqueous solution. MCIA could be easily separated from the solution after equilibrium adsorption due to its super-paramagnetic property. The functional and magnetic bio-material was an attractive adsorbent for the removal of Cd(II) from aqueous solution owing to the abundant adsorption sites, amino-group and oxygen-containing groups on the surface of Cyclosorus interruptus. The experimental results indicated that the MCIA exhibited excellent adsorption ability and the adsorption process was spontaneous and endothermic...
March 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Yuesheng Shen, Wenjin Zhu, Mengye Zhao, Guige Zhao, Geng Niu, Yuwei Bai, Bo Yang, Chao Chen, Hongli Zhu
Polymerized porcine hemoglobin (pPolyHb), a kind of glutaraldehyde-polymerized haemoglobin-based oxygen carrier, was developed as a potential red blood substitute for clinical applications. Assessment of its absorption, distribution, and metabolism is a major determinant of its safety and efficacy. In this study, a series of pharmacokinetic parameters of pPolyHb were measured and calculated in different animal models, such as the top-load model, the 50% exchange transfusion model and the haemorrhagic shock model...
March 11, 2018: Artificial Cells, Nanomedicine, and Biotechnology
Xuebo Zheng, Zhiman Yang, Xiaohui Xu, Xiaoshuang Shi, Meng Dai, Rongbo Guo
The aim of this work was to explore the potential application of biochar from distillers' grains anaerobic digestion residue pyrolyzed at 700 °C (ADR-DG700 ) to ammonium (NH4 + ) adsorption from aqueous solution, as well as its effect on NH4 + leaching from an Ultisol. The adsorption kinetic of NH4 + on the ADR-DG700 could be described by an Elovich model (R2  = 0.995), and the combined Langmuir-Freundlich model (R2  = 0.997) fitted the isotherm data better than the Langmuir, Freundlich, Redlich-Peterson, and Temkin models with a maximum adsorption of 11...
March 11, 2018: Environmental Science and Pollution Research International
Vincenzo Mirabello, Fernando Cortezon-Tamarit, Sofia I Pascu
Hypoxia has been identified as one of the hallmarks of tumor environments and a prognosis factor in many cancers. The development of ideal chemical probes for imaging and sensing of hypoxia remains elusive. Crucial characteristics would include a measurable response to subtle variations of pO2 in living systems and an ability to accumulate only in the areas of interest (e.g., targeting hypoxia tissues) whilst exhibiting kinetic stabilities in vitro and in vivo . A sensitive probe would comprise platforms for applications in imaging and therapy for non-communicable diseases (NCDs) relying on sensitive detection of pO2 ...
2018: Frontiers in Chemistry
Mara Fiorani, Andrea Guidarelli, Valentina Capellacci, Liana Cerioni, Rita Crinelli, Orazio Cantoni
Arsenite toxicity is in numerous cellular systems dependent on the formation of reactive oxygen and or nitrogen species. This is also true in U937 cells in which the metalloid selectively promotes the formation of mitochondrial superoxide (mitoO2 - ) rapidly converted to diffusible H2 O2 . We tested the hypothesis that, under the same conditions, mitoO2 - also mediates the triggering of a parallel survival signaling. We found that a low concentration of the metalloid causes an early activation of nuclear factor erythroid 2 p45-related factor 2 (Nrf2), and a downstream signaling leading to enhanced GSH biosynthesis, via a mechanism sensitive to various treatments/strategies selectively preventing mitoO2 - formation...
March 8, 2018: Toxicology and Applied Pharmacology
Cole S Bailey, Luke T Wooster, Mary Buswell, Sarvagna Patel, Paul P Pappagianopoulos, Kristian Bakken, Casey White, Melissa Tanguay, Jasmine B Blodgett, Aaron L Baggish, Rajeev Malhotra, Gregory D Lewis
OBJECTIVES: This study sought to characterize the functional and prognostic significance of oxygen uptake (VO2 ) kinetics following peak exercise in individuals with heart failure (HF). BACKGROUND: It is unknown to what extent patterns of VO2 recovery following exercise reflect circulatory response during exercise in HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). METHODS: We investigated patients (30 HFpEF, 20 HFrEF, and 22 control subjects) who underwent cardiopulmonary exercise testing with invasive hemodynamic monitoring and a second distinct HF cohort (n = 106) who underwent noninvasive cardiopulmonary exercise testing with assessment of long-term outcomes...
March 1, 2018: JACC. Heart Failure
Eric L Vu, Emad B Mossad
No abstract text is available yet for this article.
February 3, 2018: Journal of Cardiothoracic and Vascular Anesthesia
Helen Hernández, Alejandra Parra, Nicolas Tobar, Jessica Molina, Violeta Kallens, Miltha Hidalgo, Diego Varela, Jorge Martínez, Omar Porras
Aerobic metabolism brings inexorably the production of reactive oxygen species (ROS), which are counterbalanced by intrinsic antioxidant defenses avoiding deleterious intracellular effects. Redox balance is the resultant of metabolic functioning under environmental inputs (i.e. diet, pollution) and the activity of intrinsic antioxidant machinery. Monitoring of intracellular hydrogen peroxide has been successfully achieved by redox biosensor advent; however, to track the intrinsic disulfide bond reduction capacity represents a fundamental piece to understand better how redox homeostasis is maintained in living cells...
March 2, 2018: Redox Biology
Rok Sekirnik, Sarah E Wilkins, Jacob Bush, Hanna Tarhonskaya, Martin Münzel, Aayan Hussein, Emily Flashman, Shabaz Mohammed, Michael A McDonough, Christoph Loenarz, Christopher J Schofield
YcfD from Escherichia coli is a homologue of the human ribosomal oxygenases NO66 and MINA53, which catalyse histidyl-hydroxylation of the 60S subunit and affect cellular proliferation (Ge et al., Nat Chem Biol 12:960-962, 2012). Bioinformatic analysis identified a potential homologue of ycfD in the thermophilic bacterium Rhodothermus marinus (ycfDRM ). We describe studies on the characterization of ycfDRM , which is a functional 2OG oxygenase catalysing (2S,3R)-hydroxylation of the ribosomal protein uL16 at R82, and which is active at significantly higher temperatures than previously reported for any other 2OG oxygenase...
March 9, 2018: Extremophiles: Life Under Extreme Conditions
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