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https://www.readbyqxmd.com/read/28534630/an-approach-to-study-the-interactions-between-ellagitannins-and-oxygen-during-oak-wood-aging
#1
Ignacio García-Estévez, Cristina Alcalde-Eon, Ana María Martínez-Gil, Julian C Rivas-Gonzalo, M Teresa Escribano-Bailon, Ignacio Nevares, Maria Del Alamo-Sanza
During the aging of red wine in oak wood barrels, or in alternative aging systems, interactions between the compounds released from wood, the compounds of the wine and oxygen can take place. The main objective of the present work was to study oxygen-ellagitannin interactions by monitoring their levels in three model systems all containing the same amounts of French oak chips and only differing in the oxygen content: total absence, only the oxygen released from the chips and air-saturated (model systems F, OW and OS, respectively)...
May 23, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28534609/au-promoted-nickel-iron-layered-double-hydroxide-nanoarrays-a-modular-catalyst-enabling-high-performance-oxygen-evolution
#2
Wenxin Zhu, Lizhi Liu, Zhihao Yue, Wentao Zhang, Xiaoyue Yue, Jing Wang, Shaoxuan Yu, Li Wang, Jianlong Wang
Oxygen evolution reaction (OER) has played a pivotal role in many energy conversion and storage technologies like water electrolysis, fuel cells, and metal-air batteries. However, the slow kinetics of OER limit the performance and commercialization of such devices. Herein, we report on NiFe LDH@Au hybrid nanoarrays on Ni foam for much enhanced OER. By hybridization of electronegative Au and NiFe LDH with intrinsic remarkable OER catalytic activity, this modular electrode could drive an overall ultrahigh-performance and robust OER in base with the demand of overpotentials of only 221, 235 and 270 mV to afford 50, 100 and 500 mA cm-2, respectively...
May 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28530798/heterogeneous-molecular-catalysis-of-electrochemical-reactions-volcano-plots-and-catalytic-tafel-plots
#3
Cyrille Costentin, Jean-Michel Savéant
We analyze here, in the framework of heterogeneous mo-lecular catalysis the reasons of occurrence or non-occurrence of volcanoes upon plotting the kinetics of the catalytic reaction versus the stabilization free energy of the primary intermediate of the catalytic process. As in the case of homogeneous molecular catalysis or catalysis by surface active metallic sites, a strong motivation of such studies relates to modern energy challenges, particularly those involving small molecules such as water, hydrogen, oxygen, proton and carbon dioxide...
May 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28530505/ingestion-of-sodium-bicarbonate-nahco3-following-a-fatiguing-bout-of-exercise-accelerates-post-exercise-acid-base-balance-recovery-and-improves-subsequent-high-intensity-cycling-time-to-exhaustion
#4
Lewis A Gough, Steven Rimmer, Callum J Osler, Matthew F Higgins
This study evaluated the ingestion of sodium bicarbonate (NaHCO3) on post-exercise acid-base balance recovery kinetics and subsequent high-intensity cycling time to exhaustion. In a counterbalanced, crossover design, nine healthy and active males (age: 23±2 years, height: 179±5 cm, body mass: 74±9 kg, peak mean minute power (WPEAK) 256±45 W, peak oxygen uptake (V̇O2PEAK) 46±8 ml.kg(-1).min(-1)) performed a graded incremental exercise test, two familiarisation and two experimental trials. Experimental trials consisted of cycling to volitional exhaustion (TLIM1) at 100% WPEAK on two occasions (TLIM1 and TLIM2) interspersed by a 90 min passive recovery period...
May 22, 2017: International Journal of Sport Nutrition and Exercise Metabolism
https://www.readbyqxmd.com/read/28530476/time-trials-versus-time-to-exhaustion-tests-effects-on-critical-power-w-and-oxygen-uptake-kinetics
#5
Bettina Karsten, Jonathan Baker, Fernando Naclerio, Andreas Klose, Antonino Bianco, Alfred Nimmerichter
PURPOSE: To investigate single-day time-to-exhaustion (TTE) and time trial (TT) based laboratory tests values of critical power (CP), Wprime (W') and respective oxygen kinetics responses. METHODS: Twelve cyclists performed a maximal ramp test followed by three TTE and three TT efforts interspersed by a 60-min recovery between efforts. Oxygen uptake was measured during all trials. The mean response time (MRT) was calculated as a description of the overall V̇O2 kinetic response from the onset to 2 min of exercise...
May 22, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28527627/a-kinetic-study-on-the-reactivity-of-azanone-hno-toward-its-selected-scavengers-insight-into-its-chemistry-and-detection
#6
Renata Smulik-Izydorczyk, Adrianna Mesjasz, Angelika Gerbich, Jan Adamus, Radosław Michalski, Adam Sikora
Recently, azanone (HNO), which is the protonated one-electron reduction product of (·)NO, has gained considerable attention due to its unique pharmacological effects. Although there has been much progress in understanding HNO biology and chemistry, it remains the most elusive reactive nitrogen species. Herein, we applied the competition kinetics method, based on two parallel HNO reactions with the different scavengers and molecular oxygen (kO2 = (1.8 ± 0.3) × 10(4) M(-1) s(-1)), to determine the rate constants for the reactions of HNO with its selected co-reactants...
May 17, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/28526768/direct-comparison-of-the-enzymatic-characteristics-and-superoxide-production-of-the-four-aldehyde-oxidase-enzymes-present-in-mouse
#7
Gokhan Kucukgoze, Mineko Terao, Enrico Garattini, Silke Leimkuhler
Aldehyde oxidases (AOXs) are molybdoflavoenzymes with an important role in the metabolism and detoxification of heterocyclic compounds and aliphatic as well as aromatic aldehydes. The enzymes use oxygen as the terminal electron acceptor and produce reduced oxygen species during turnover. Four different enzymes, mAOX1, mAOX3, mAOX4 and mAOX2, which are the products of distinct genes, are present in the mouse. A direct and simultaneous comparison of the enzymatic properties and characteristics of the four enzymes has never been performed...
May 19, 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28525861/an-experimental-and-theoretical-study-of-solvent-hydrogen-bond-donating-capacity-effects-on-ultrafast-intramolecular-charge-transfer-of-ld-490
#8
Hui Li, Hang Yin, Xiaochun Liu, Ying Shi, Mingxing Jin, Dajun Ding
The excited-state intramolecular charge transfer (ICT) of LD 490 were investigated in different hydrogen-bond-donating solvents (α scale) on the basis of the Kamlet-Taft solvatochromic parameters (π*, α, β). The femtosecond transient absorption spectra and the kinetics decay rate reveal that with an increase of solvent's α capacity, the long-lived picosecond process, which is attributed to the ICT, becomes much faster. Combining with time-dependent density functional theory (TDDFT) calculations, we demonstrate that the enhancement of α acidity substantially increases the electronegativity of the carbonyl oxygen in LD 490, which strengthen excited-state intermolecular hydrogen bonding interactions and consequently facilitate the ICT process...
May 15, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28524207/untangling-surface-oxygen-exchange-effects-in-yba2cu3o6-x-thin-films-by-electrical-conductivity-relaxation
#9
P Cayado, C F Sánchez-Valdés, A Stangl, M Coll, P Roura, A Palau, T Puig, X Obradors
The kinetics of oxygen incorporation (in-diffusion process) and excorporation (out-diffusion process), in YBa2Cu3O6+x (YBCO) epitaxial thin films prepared using the chemical solution deposition (CSD) methodology by the trifluoroacetate route, was investigated by electrical conductivity relaxation measurements. We show that the oxygenation kinetics of YBCO films is limited by the surface exchange process of oxygen molecules prior to bulk diffusion into the films. The analysis of the temperature and oxygen partial pressure influence on the oxygenation kinetics has drawn a consistent picture of the oxygen surface exchange process enabling us to define the most likely rate determining step...
May 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28521517/dynamic-model-of-vascular-targeted-photodynamic-therapy
#10
Xiao-Ming Hu, Linhuan He, Yi Zhao
Vascular-targeted photodynamic therapy has shown efficiency in treating port wine stains. A dynamic model that incorporates blood flow, kinetic diffusion, oxygen and photosensitizer consumption and reaction, and light modulation is proposed to reveal the interactions among light, photosensitizer, and oxygen. Simulation results show that pulse light modulation synchronized with heartbeats hold the advantage of increased singlet oxygen accumulation, higher oxygen concentration and lower temperature. Meanwhile, constant light treatment is advantageous in terms of higher temperature, lower total oxygen concentration and singlet oxygen accumulation...
May 19, 2017: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/28521161/visible-light-photo-fenton-oxidation-of-phenol-with-rgo-%C3%AE-feooh-supported-on-al-doped-mesoporous-silica-mcm-41-at-neutral-ph-performance-and-optimization-of-the-catalyst
#11
Ying Wang, Mingxing Liang, Jiasheng Fang, Jun Fu, Xiaochun Chen
In this study, α-FeOOH on reduced graphene oxide (rGO-α-FeOOH) supported on an Al-doped MCM-41 catalyst (RFAM) was optimized for the visible-light photo-Fenton oxidation of phenol at neutral pH. The stability of the catalysts, effect of bubbling aeration, and degradation intermediates were investigated. Results indicated that RFAM with a large Brunauer-Emmett-Teller (BET) area and mesoporous structure displayed excellent catalytic activity for the visible-light-driven (VLD) photo-Fenton process. Phenol degradation was well described by a pseudo-first-order reaction kinetics model...
May 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28515572/a-family-of-fe-n-c-oxygen-reduction-electrocatalysts-for-microbial-fuel-cell-mfc-application-relationships-between-surface-chemistry-and-performances
#12
Carlo Santoro, Alexey Serov, Rohan Gokhale, Santiago Rojas-Carbonell, Lydia Stariha, Jonathan Gordon, Kateryna Artyushkova, Plamen Atanassov
Different iron-based cathode catalysts have been studied for oxygen reduction reaction (ORR) in neutral media and then applied into microbial fuel cells (MFC). The catalysts have been synthesized using sacrificial support method (SSM) using eight different organic precursors named Niclosamide, Ricobendazole, Guanosine, Succinylsulfathiazole, Sulfacetamide, Quinine, Sulfadiazine and Pyrazinamide. Linear Sweep Voltammetry (LSV) curves were obtained for the catalysts using a O2 saturated in 0.1 M potassium phosphate buffer and 0...
May 15, 2017: Applied Catalysis. B, Environmental
https://www.readbyqxmd.com/read/28515001/in-vitro-extracellular-matrix-accumulation-of-nasal-and-articular-chondrocytes-for-intervertebral-disc-repair
#13
S Vedicherla, C T Buckley
Chondrocyte based regenerative therapies for intervertebral disc repair such as Autologous Disc Cell Transplantation (ADCT, CODON) and allogeneic juvenile chondrocyte implantation (NuQu(®), ISTO Technologies) have demonstrated good outcomes in clinical trials. However concerns remain with the supply demand reconciliation and issues surrounding immunoreactivity which exist for allogeneic-type technologies. The use of stem cells is challenging due to high growth factor requirements, regulatory barriers and differentiation towards a stable phenotype...
May 8, 2017: Tissue & Cell
https://www.readbyqxmd.com/read/28514247/corneal-equilibrium-flux-as-a-function-of-corneal-surface-oxygen-tension
#14
Vicente Compañ, Marcel Aguilella-Arzo, Barry A Weissman
PURPOSE: Oxygen is essential for aerobic mammalian cell physiology. Oxygen tension (PO2) should reach a minimum at some position within the corneal stroma, and oxygen flux should be zero, by definition, at this point as well. We found the locations and magnitudes of this "corneal equilibrium flux" (xmin) and explored its physiological implications. METHODS: We used an application of the Monod kinetic model to calculate xmin for normal human cornea as anterior surface PO2 changes from 155 to 20 mmHg...
May 16, 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28513886/regulating-water-reduction-kinetics-in-cobalt-phosphide-for-enhancing-her-catalytic-activity-in-alkaline-solution
#15
Kun Xu, Hui Ding, Mengxing Zhang, Min Chen, Zikai Hao, Lidong Zhang, Changzheng Wu, Yi Xie
Electrochemical water splitting to produce hydrogen renders a promising pathway for renewable energy storage. Considering limited electrocatalysts have good oxygen-evolution reaction (OER) catalytic activity in acid solution while numerous economical materials show excellent OER catalytic performance in alkaline solution, developing new strategies that enhance the alkaline hydrogen-evolution reaction (HER) catalytic activity of cost-effective catalysts is highly desirable for achieving highly efficient overall water splitting...
May 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28513669/the-open-cubane-oxo-oxyl-coupling-mechanism-dominates-photosynthetic-oxygen-evolution-a-comprehensive-dft-investigation-on-o-o-bond-formation-in-the-s4-state
#16
Yu Guo, Hui Li, Lan-Lan He, Dong-Xia Zhao, Li-Dong Gong, Zhong-Zhi Yang
The dioxygen formation mechanism of biological water oxidation in nature has long been the focus of argument; many diverse mechanistic hypotheses have been proposed. Based on a recent breakthrough in the resolution of the electronic and structural properties of the oxygen-evolving complex in the S3 state, our density functional theory (DFT) calculations reveal that the open-cubane oxo-oxyl coupling mechanism, whose substrates preferably originate from W2 and O5 in the S2 state, emerges as the best candidate for O-O bond formation in the S4 state...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28508560/anionic-regulated-nife-oxy-sulfide-electrocatalysts-for-water-oxidation
#17
Bo-Quan Li, Shu-Yuan Zhang, Cheng Tang, Xiaoyang Cui, Qiang Zhang
The construction of active sites with intrinsic oxygen evolution reaction (OER) is of great significance to overcome the limited efficiency of abundant sustainable energy devices such as fuel cells, rechargeable metal-air batteries, and in water splitting. Anionic regulation of electrocatalysts by modulating the electronic structure of active sites significantly promotes OER performance. To prove the concept, NiFeS electrocatalysts are fabricated with gradual variation of atomic ratio of S:O. With the rise of S content, the overpotential for water oxidation exhibits a volcano plot under anionic regulation...
May 16, 2017: Small
https://www.readbyqxmd.com/read/28508468/visible-light-responsive-color-switching-driven-by-photocatalytic-self-doped-sno2-x-nanocrystals
#18
Dan Han, Baolai Jiang, Ji Feng, Yadong Yin, Wenshou Wang
Visible light-responsive reversible color switching systems are attractive to many applications since visible light has superior penetration and causes far less damages to organic molecules than UV. Here we report that self-doping of Sn2+ in SnO2-x nanocrystals red shifts their absorption to visible region and simultaneously produces oxygen vacancies, which can effectively scavenge photogenerated holes and thus enable color switching of redox dyes using visible light. Wavelength selective switching can also be achieved by coupling the photocatalytic activity of the SnO2-x NCs with the color switching kinetics of different redox dyes...
May 16, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28508113/doubly-labelled-water-assessment-of-energy-expenditure-principle-practice-and-promise
#19
REVIEW
Klaas R Westerterp
The doubly labelled water method for the assessment of energy expenditure was first published in 1955, application in humans started in 1982, and it has become the gold standard for human energy requirement under daily living conditions. The method involves enriching the body water of a subject with heavy hydrogen ((2)H) and heavy oxygen ((18)O), and then determining the difference in washout kinetics between both isotopes, being a function of carbon dioxide production. In practice, subjects get a measured amount of doubly labelled water ((2)H 2(18) O) to increase background enrichment of body water for (18)O of 2000 ppm with at least 180 ppm and background enrichment of body water for (2)H of 150 ppm with 120 ppm...
May 15, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28508082/a-chlorine-free-protocol-for-processing-germanium
#20
Martin Glavinović, Michael Krause, Linju Yang, John A McLeod, Lijia Liu, Kim M Baines, Tomislav Friščić, Jean-Philip Lumb
Replacing molecular chlorine and hydrochloric acid with less energy- and risk-intensive reagents would markedly improve the environmental impact of metal manufacturing at a time when demand for metals is rapidly increasing. We describe a recyclable quinone/catechol redox platform that provides an innovative replacement for elemental chlorine and hydrochloric acid in the conversion of either germanium metal or germanium dioxide to a germanium tetrachloride substitute. Germanium is classified as a "critical" element based on its high dispersion in the environment, growing demand, and lack of suitable substitutes...
May 2017: Science Advances
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