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Oxygen kinetics

Tatiane Piucco, Rogério Soares, Fernando Diefenthaeler, Guillaume Millet, Juan Murias
PURPOSE: this study aimed to compare the oxygen uptake (V̇O2) kinetics during skating on a treadmill and skating on a slide board and discuss potential mechanisms that might control the V̇O2 kinetics responses during skating. METHODS: breath-by-breath pulmonary V̇O2 and near-infrared spectroscopy-derived muscle deoxygenation ([HHbMb]) were monitored continuously in 12 well-trained young long track speed skaters. On-transient V̇O2 and [HHbMb] responses to skating on a treadmill and skating on a slide board at 80% of the estimated gas exchange threshold were fitted as mono-exponential function...
November 15, 2017: International Journal of Sports Physiology and Performance
Marianna Basso Jorge, Adalto Bianchini, Chris M Wood, Patricia L Gillis
The early life stages of freshwater mussels are particularly sensitive to Cu contamination. We measured the acute toxicity, bioaccumulation and sublethal effects of Cu in glochidia. Additionally, we used radiolabeled Cu ((64) Cu) to examine the time-dependent kinetics of uptake over 24 h. (64) Cu uptake by live and dead glochidia exposed to 0.11 μmol/L exhibited similar hyperbolic patterns over the first 40 min, indicating an adsorptive phase independent of larval metabolism. Thereafter, uptake was linear with time, with a 10-fold lower bioaccumulation rate in live than in dead animals, representing a close to steady state of Cu regulation...
November 15, 2017: Environmental Toxicology and Chemistry
Antonio Garcia-Jimenez, Jose Antonio Teruel-Puche, Pedro Antonio Garcia-Ruiz, Adrian Saura-Sanmartin, Jose Berna, Francisco Garcia-Canovas, José Neptuno Rodriguez-Lopez
Deoxyarbutin, a potent inhibitor of tyrosinase, could act as substrate of the enzyme. Oxytyrosinase is able to hydroxylate deoxyarbutin and finishes the catalytic cycle by oxidizing the formed o-diphenol to quinone, while the enzyme becomes deoxytyrosinase, which evolves to oxytyrosinase in the presence of oxygen. This compound is the only one described that does not release o-diphenol after the hydroxylation step. Oxytyrosinase hydroxylates the deoxyarbutin in ortho position of the phenolic hydroxyl group by means of an aromatic electrophilic substitution...
2017: PloS One
Liang Jing, Bing Chen, Diya Wen, Jisi Zheng, Baiyu Zhang
In this study, a UV/O3 hybrid advanced oxidation system was used to remove chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and atrazine (ATZ) from ATZ production wastewater. The removal of COD and NH3-N, under different UV and O3 conditions, was found to follow pseudo-first-order kinetics with rate constants ranging from 0.0001-0.0048 and 0.0015-0.0056 min(-1), respectively. The removal efficiency of ATZ was over 95% after 180 min treatment, regardless the level of UV power. A kinetic model was further proposed to simulate the removal processes and to quantify the individual roles and contributions of photolysis, direct O3 oxidation, and hydroxyl radical (OH·) induced oxidation...
November 13, 2017: Environmental Science and Pollution Research International
M Butler, Ing U Reichl
The glycan profile of therapeutic recombinant proteins such as monoclonal antibodies is a critical quality attribute, which affects the efficacy of the final product. The cellular glycosylation process during protein expression is dependent upon a number of factors such as the availability of substrates in the media, the intracellular content of nucleotide sugars, and the enzyme repertoire of the host cells. In order to control the variability of glycosylation it is important to understand the critical process parameters and their acceptable range of values to enable reproducible production of proteins with a predetermined glycan profile providing the desired biological function or therapeutic effect...
October 3, 2017: Advances in Biochemical Engineering/biotechnology
Frank B Jensen, Karsten Nielsen
Red blood cells (RBCs) possess methemoglobin reductase activity that counters the ongoing oxidation of hemoglobin (Hb) to methemoglobin (metHb), which in circulating blood is caused by Hb autoxidation or reactions with nitrite. We describe an assay for determining metHb reductase activity in intact RBCs in physiological saline at normal Pco2 and pH. After initial loading of oxygenated RBCs with nitrite (partly oxidizing Hb to metHb), the nitrite is removed by three washes of the RBCs in nitrite-free physiological saline to enable the detection of RBC metHb reductase activity in the absence of counteracting oxidation...
November 10, 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
Birgit Koehler, Francesco Barsotti, Marco Minella, Tomas Landelius, Claudio Minero, Lars J Tranvik, Davide Vione
Lake water constituents, such as chromophoric dissolved organic matter (CDOM) and nitrate, absorb sunlight which induces an array of photochemical reactions. Although these reactions are a substantial driver of pollutant degradation in lakes they are insufficiently understood, in particular on large scales. Here, we provide for the first time comprehensive photochemical maps covering a large geographic region. Using photochemical kinetics modeling for 1048 lakes across Sweden we simulated the steady-state concentrations of four photoreactive transient species, which are continuously produced and consumed in sunlit lake waters...
October 30, 2017: Water Research
Jing Sun, Bing-Jie Ni, Keshab Raj Sharma, Qilin Wang, Shihu Hu, Zhiguo Yuan
Reliable modelling of sulfide and methane production in sewer systems is required for efficient sewer emission management. Wastewater compositions affect sulfide and methane production kinetics through both its short-term variation influencing the substrate availability to sewer biofilms, and its long-term variation affecting the sewer biofilm structure. While the short-term effect is well considered in existing sewer models with the use of Monod or half-order equations, the long-term effect has not been explicitly considered in current sewer models suitable for network modelling...
November 3, 2017: Water Research
Valerii P Tarasov, Gayana А Kirakosyan, Konstantin E German
(99) Tc NMR has been suggested as an original method of evaluating the content of oxygen isotopes in oxygen-18 enriched water, a precursor for the production of radioisotope fluorine-18 used in positron emission tomography. To this end, solutions of NH4 TcO4 or NaTcO4 (up to 0.28 mol/L) with natural abundance of oxygen isotopes in virgin or recycled (18) O-enriched water have been studied by (99) Tc NMR. The method is based on (16) O/(17) O/(18) O intrinsic isotope effects in the (99) Tc NMR chemical shifts and the statistical distribution of oxygen isotopes in the coordination sphere of TcO4(-) and makes it possible to quantify the composition of enriched water by measuring the relative intensities of the (99) Tc NMR signals of the Tc(16) O4 - n(18) On(-) isotopologues...
November 11, 2017: Magnetic Resonance in Chemistry: MRC
Simeng Li, Gang Chen
Microbial fuel cell (MFC) is a novel technology for landfill leachate treatment with simultaneous electric power generation. In recent years, more and more modern landfills are operating as bioreactors to shorten the time required for landfill stabilization and improve the leachate quality. For landfills to operate as biofilters, leachate is recirculated back to the landfill, during which time the organics of the leachate can be decomposed. Continuous recirculation typically results in evolving leachate quality, which chronologically corresponds to evolution stages such as hydrolysis, acidogenesis, acetogenesis, methanogenesis, and maturation...
November 1, 2017: Waste Management & Research
Bing Tan, Huimin Zhao, Yaobin Zhang, Xie Quan, Zehao He, Wenting Zheng, Bingyu Shi
Phytic acid (PA) induced graphene macrostructures were synthesized and investigated for the sorption characteristics and mechanisms of mercury. The as-synthesized graphene foam possessed large specific surface area and amphiphilicity. FTIR and XPS analysis revealed that the as-prepared graphene macrostructure retained oxygen-containing functional groups after hydrothermal reduction and also captured new phosphorus-containing groups because of the introduction of PA. Different experimental parameters, such as pH, PA fractions and contact time were applied to probe into the Hg(II) adsorption performance of as-synthesized macrostructure...
October 26, 2017: Journal of Colloid and Interface Science
Haiying Qin, Longxia Lin, Junkang Jia, Huangliang Ni, Yan He, Juan Wang, Aiguo Li, Zhenguo Ji, Jiabin Liu
Transition metal-based composites are one of the most important electrocatalysts because of their rich redox chemistry. The reaction kinetics of a redox couple is dependent on the chemical valence and is a key issue in electrocatalytic performance. In this study, a metallic Co catalyst was synthesized by pyrolyzing Co(OH)2. The effect of the chemical valence of Co on the oxygen reduction reaction (ORR) was investigated by comparing the electrocatalytic properties of three Co-based catalysts containing Co(0), Co(2+), and Co(3+)...
November 10, 2017: Physical Chemistry Chemical Physics: PCCP
Bin Lee, Dong Gun Lee
Silibinin is the major active component of silymarin, extracted from medicinal plant Silybum marianum. Silibinin has potent antibacterial activity; however, the exact mechanism underlying its activity has not been elucidated. Here, we investigated the novel mechanism of silibinin against Escherichia coli. Time-kill kinetic assay showed that silibinin possess a bactericidal effect at minimal inhibitory concentration (MIC) and higher concentrations (two and four-fold MIC). At the membrane depolarization and increased intracellular Ca²⁺ levels were observed, considered as characteristics of bacterial apoptosis...
November 9, 2017: Journal of Microbiology and Biotechnology
Yang Li, Lei Li, Zi-Xi Chen, Jie Zhang, Li Gong, Yi-Xuan Wang, Han-Qing Zhao, Yang Mu
Advanced oxidation processes offer effective solutions in treating wastewater from various industries. This study is the first time to investigate the potential of carbonate-activated hydrogen peroxide (CAP) oxidation process for the removal of organic pollutant from highly alkaline wastewaters. Azo dye acid orange 7 (AO7) was selected as a model pollutant. The influences of various parameters on AO7 decolorization by the CAP oxidation were evaluated. Furthermore, the active species involved in AO7 degradation were explored using scavenger experiments and electron spin resonance analysis...
November 6, 2017: Chemosphere
Tan Huang, Yu Chen, Jong-Min Lee
Developing highly efficient electrocatalysts for oxygen evolution is vital for renewable and sustainable energy production and storage. Herein, nitrogen-doped carbon encapsulated CoOx-MoC heterostructures are reported for the first time as high performance oxygen evolution electrocatalysts. The composition can be tuned by the addition of a Mo source to form a nanowire-assembled hierarchically porous microstructure, which can enlarge the specific surface area, thus exposing more active sites, facilitating mass transport and charge transfer...
November 9, 2017: Small
Fábio J Lanferdini, Renata L Krüger, Bruno M Baroni, Caetano Lazzari, Pedro Figueiredo, Alvaro Reischak-Oliveira, Marco A Vaz
Some evidence supports that low-level laser therapy (LLLT) reduces neuromuscular fatigue, so incrementing sports performance. A previous randomized controlled trial of our group showed increased exercise tolerance in male competitive cyclists treated with three different LLLT doses (3, 6, and 9 J/diode; or 135, 270, and 405 J/thigh) before time-to-exhaustion cycling tests. Now, the present study was designed to evaluate the effects of these LLLT doses on the VO2 kinetics of athletes during cycling tests. Twenty male competitive cyclists (29 years) participated in a crossover, randomized, double-blind, and placebo-controlled trial...
November 9, 2017: Lasers in Medical Science
Jitandrakumar R Patel, Gregory P Barton, Rudolf K Braun, Kara N Goss, Kristin Haraldsdottir, Alexandria Hopp, Gary Diffee, Timothy A Hacker, Richard L Moss, Marlowe W Eldridge
Infants born premature are at increased risk for development of bronchopulmonary dysplasia (BPD), pulmonary hypertension (PH), and ultimately right ventricular (RV) dysfunction, which together carry a high risk of neonatal mortality. However, the role alveolar simplification and abnormal pulmonary microvascular development in BPD affects RV contractile properties is unknown. We used a rat model of BPD to examine the effect of hyperoxia-induced PH on RV contractile properties. We measured in vivo RV pressure as well as passive force, maximum Ca(2+) activated force, calcium sensitivity of force (pCa50) and rate of force redevelopment (ktr) in RV skinned trabeculae isolated from hearts of 21-and 35-day old rats pre-exposed to 21% oxygen (normoxia) or 85% oxygen (hyperoxia) for 14 days after birth...
2017: Frontiers in Physiology
Florent Baty, Christian Ritz, Signe Marie Jensen, Lukas Kern, Michael Tamm, Martin Hugo Brutsche
6-min walk tests (6MWT) are routinely performed in patients with chronic obstructive pulmonary disease (COPD). Oxygen uptake ([Formula: see text]) kinetics during 6MWT can be modeled and derived parameters provide indicators of patients' exercise capacity. Post-exercise [Formula: see text] recovery also provides important parameters of patients' fitness which has not been extensively investigated in COPD. Several nonlinear regression models with different underlying biological assumptions may be suitable for describing recovery kinetics...
2017: PloS One
Quan Yuan, Linda Lorraine Pearce, Jim Peterson
In aqueous media at neutral pH, the binding of two cyanide molecules per cobinamide can be described by two formation constants, Kf1 = 1.1 (±0.6) × 105 M-1 and Kf2 = 8.5 (±0.1) × 104 M-1, or an overall cyanide binding constant of ~1 × 1010 M-2. In comparison, the cyanide binding constants for cobalamin and a fully oxidized form of cytochrome c oxidase, each binding a single cyanide anion, were found to be 7.9 (±0.5) × 104 M-1 and 1.6 (±0.2) × 107 M-1, respectively. An examination of the cyanide-binding properties of cobinamide at neutral pH by stopped-flow spectrophotometry revealed two kinetic phases, rapid and slow, with apparent second-order rate constants of 3...
November 8, 2017: Chemical Research in Toxicology
Chongliang Gao, Gianluca Catucci, Silvia Castrignanò, Gianfranco Gilardi, Sheila J Sadeghi
Human flavin-containing monooxygenase 3 (hFMO3) catalyses the oxygenation of a wide variety of compounds including drugs as well as dietary compounds. It is the major hepatic enzyme involved in the production of the N-oxide of trimethylamine (TMAO) and clinical studies have uncovered a striking correlation between plasma TMAO concentration and cardiovascular disease. Certain mutations within the hFMO3 gene cause defective trimethylamine (TMA) N-oxygenation leading to trimethylaminuria (TMAU) also known as fish-odour syndrome...
November 7, 2017: Scientific Reports
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