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Oxygen kinetics

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https://www.readbyqxmd.com/read/27914644/comparison-of-bacterial-growth-in-response-to-photodegraded-terrestrial-chromophoric-dissolved-organic-matter-in-two-lakes
#1
Yaling Su, En Hu, Muhua Feng, Yongdong Zhang, Feizhou Chen, Zhengwen Liu
Terrestrial chromophoric dissolved organic matter (CDOM) could subsidize lake food webs. Trophic state and altitude have a pronounced influence on the CDOM concentration and composition of a lake. The impact of future changes in solar radiation on high-altitude lakes is particularly alarming because these aquatic ecosystems experience the most pronounced radiation variation worldwide. Photodegradation experiments were conducted on terrestrial CDOM samples from oligotrophic alpine Lake Tiancai and low-altitude eutrophic Lake Xiaohu to investigate the response of bacterial growth to photodegraded CDOM...
November 30, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27913171/effects-of-hydraulic-retention-time-hrt-on-denitrification-using-waste-activated-sludge-thermal-hydrolysis-liquid-and-acidogenic-liquid-as-carbon-sources
#2
Yiding Guo, Liang Guo, Mei Sun, Yangguo Zhao, Mengchun Gao, Zonglian She
Waste activated sludge (WAS) internal carbon source can efficiently and economically enhance denitrification, and hydraulic retention time (HRT) is one of the most important operational parameters for denitrification. The effects of HRT on denitrification were investigated with WAS thermal hydrolysis liquid and acidogenic liquid as carbon sources in this study. The optimal HRT was 12h for thermal hydrolysis liquid and 8h for acidogenic liquid, with NO3(-)-N removal efficiency of 91.0% and 97.6%, respectively...
November 15, 2016: Bioresource Technology
https://www.readbyqxmd.com/read/27912190/nanostructured-3d-porous-graphene-hydrogel-based-ti-sb-sno2-gr-electrode-with-enhanced-electrocatalytic-activity
#3
Sumreen Asim, Yunqing Zhu, Masud Rana, Jiao Yin, Muhammad Wajid Shah, Yingxuan Li, Chuanyi Wang
Nanostructured highly porous 3D-Ti/Sb-SnO2-Gr electrode, based on 3D porous graphene hydrogel was fabricated via a fast-evaporation technique through layer by layer (LBL) deposition. The 3D pores are uniformly distributed on the high fidelity of substrate with pore sizes of 7-12 nm, as confirmed by SEM analysis. Compared to Ti/Sb-SnO2 electrode, the fabricated 3D porous electrode possesses high oxygen evolution potential (2.40 V), smaller charge transfer resistance (29.40 Ω cm(-2)), higher porosity (0...
November 29, 2016: Chemosphere
https://www.readbyqxmd.com/read/27911826/structural-insights-into-the-lcib-protein-family-reveals-a-new-group-of-%C3%AE-carbonic-anhydrases
#4
Shengyang Jin, Jian Sun, Tobias Wunder, Desong Tang, Asaph B Cousins, Siu Kwan Sze, Oliver Mueller-Cajar, Yong-Gui Gao
Aquatic microalgae have evolved diverse CO2-concentrating mechanisms (CCMs) to saturate the carboxylase with its substrate, to compensate for the slow kinetics and competing oxygenation reaction of the key photosynthetic CO2-fixing enzyme rubisco. The limiting CO2-inducible B protein (LCIB) is known to be essential for CCM function in Chlamydomonas reinhardtii To assign a function to this previously uncharacterized protein family, we purified and characterized a phylogenetically diverse set of LCIB homologs...
December 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27909686/lipofuscins-prepared-by-modification-of-photoreceptor-cells-via-glycation-or-lipid-peroxidation-show-the-similar-phototoxicity
#5
Alexander Dontsov, Anna Koromyslova, Mikhail Ostrovsky, Natalia Sakina
AIM: To investigate the effect of two ways of lipofuscin production (lipid peroxidation and glycation) on lipofuscin fluorescence characteristics and phototoxicity and to compare them with the properties of natural lipofuscin. METHODS: Model lipofuscins were prepared on the basis of bovine photoreceptor outer segments (POS) with bisretinoid A2E addition. One set of samples was prepared from POS modified by lipid peroxidation, while another set from POS modified by glycation with fructose...
November 20, 2016: World Journal of Experimental Medicine
https://www.readbyqxmd.com/read/27908452/kinetics-and-mechanisms-of-nitrate-and-ammonium-formation-during-ozonation-of-dissolved-organic-nitrogen
#6
Glen Andrew de Vera, Wolfgang Gernjak, Howard Weinberg, Maria José Farré, Jurg Keller, Urs von Gunten
Dissolved organic nitrogen (DON) is an emerging concern in oxidative water treatment because it exerts oxidant demand and may form nitrogenous oxidation/disinfection by-products. In this study, we investigated the reactions of ozone with DON with a special emphasis on the formation of nitrate (NO3(-)) and ammonium (NH4(+)). In batch ozonation experiments, the formation of NO3(-) and NH4(+) was investigated for natural organic matter standards, surface water, and wastewater effluent samples. A good correlation was found between NO3(-) formation and the O3 exposure (R(2) > 0...
October 8, 2016: Water Research
https://www.readbyqxmd.com/read/27907122/biodegradation-of-methyl-tertiary-butyl-ether-mtbe-by-a-microbial-consortium-in-a-continuous-up-flow-packed-bed-biofilm-reactor-kinetic-study-metabolite-identification-and-toxicity-bioassays
#7
Guadalupe Alfonso-Gordillo, César Mateo Flores-Ortiz, Liliana Morales-Barrera, Eliseo Cristiani-Urbina
This study investigated the aerobic biodegradation of methyl tertiary-butyl ether (MTBE) by a microbial consortium in a continuous up-flow packed-bed biofilm reactor using tezontle stone particles as a supporting material for the biofilm. Although MTBE is toxic for microbial communities, the microbial consortium used here was able to resist MTBE loading rates up to 128.3 mg L-1 h-1, with removal efficiencies of MTBE and chemical oxygen demand (COD) higher than 90%. A linear relationship was observed between the MTBE loading rate and the MTBE removal rate, as well as between the COD loading rate and the COD removal rate, within the interval of MTBE loading rates from 11...
2016: PloS One
https://www.readbyqxmd.com/read/27905597/mechanism-for-the-enhanced-oxygen-reduction-reaction-of-la0-6sr0-4co0-2fe0-8o3-%C3%AE-by-strontium-carbonate
#8
Mei Li, Zhongti Sun, Wenqiang Yang, Tao Hong, Zhesheng Zhu, Yanxiang Zhang, Xiaojun Wu, Changrong Xia
Strontium doped lanthanum cobalt ferrite (LSCF) is a widely applied electrocatalyst for the oxygen reduction reaction (ORR) in solid-oxide fuel cells (SOFCs) operated at intermediate temperatures. Sr surface segregation in long-term operation has been reported to have contradicting effects that either degrade or improve the reaction. Thus, it is critical to understand the mechanism of surface Sr compounds on ORR kinetics. This work aims to verify the effect and propose the mechanism by decorating SrCO3 nanoparticles using the infiltration method...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27905295/desensitization-of-idiopathic-pulmonary-fibrosis-fibroblasts-to-alternaria-alternata-extract-mediated-necrotic-cell-death
#9
Jintaek Im, Kyutae Kim, Ji Young Yhee, Scott M O'Grady, Richard S Nho
Alternaria alternata is an allergenic fungus and known to cause an upper respiratory tract infection and asthma in humans with compromised immunity. Although A. alternata's effect on airway epithelial cells has previously been examined, the potential role of A. alternata on lung fibroblast viability is not understood. Since lung fibroblasts derived from patients with idiopathic pulmonary fibrosis (IPF) display a distinct phenotype that is resistant to stress and cell death inducing conditions, the investigation of the role of Alternaria on pathological IPF fibroblasts provides a better understanding of the fibrotic process induced by an allergenic fungus...
November 2016: Physiological Reports
https://www.readbyqxmd.com/read/27904989/respirometric-response-and-microbial-succession-of-nitrifying-sludge-to-m-cresol-pulses-in-a-sequencing-batch-reactor
#10
Alberto Ordaz, Mariana Sánchez, Rodrigo Rivera, Rafael Rojas, Alejandro Zepeda
A nitrifying consortium was kinetically, stoichiometrically and molecularly characterized via the in situ pulse respirometric method and pyrosequencing analysis before and after the addition of m-cresol (25 mg C L(-1)) in a sequencing batch reactor (SBR). Five important kinetic and stoichiometric parameters were determined: the maximum oxygen uptake rate, the maximum nitrification rate, the oxidation yield, the biomass growth yield, and the substrate affinity constant. An inhibitory effect was observed in the nitrification process with a recovery of this by up to eight SBR cycles after m-cresol was added to the system...
November 30, 2016: Biodegradation
https://www.readbyqxmd.com/read/27904934/part-2-analytical-expressions-of-concentrations-of-glucose-oxygen-and-gluconic-acid-in-a-composite-membrane-for-closed-loop-insulin-delivery-for-the-non-steady-state-conditions
#11
N Mehala, L Rajendran, V Meena
A mathematical model developed by Abdekhodaie and Wu (J Membr Sci 335:21-31, 2009), which describes a dynamic process involving an enzymatic reaction and diffusion of reactants and product inside glucose-sensitive composite membrane has been discussed. This theoretical model depicts a system of non-linear non-steady state reaction diffusion equations. These equations have been solved using new approach of homotopy perturbation method and analytical solutions pertaining to the concentrations of glucose, oxygen, and gluconic acid are derived...
November 30, 2016: Journal of Membrane Biology
https://www.readbyqxmd.com/read/27901149/co-oxidation-by-the-atomic-oxygen-on-silver-clusters-structurally-dependent-mechanisms-generating-free-or-chemically-bonded-co2
#12
Xizi Cao, Mengyi Chen, Jun Ma, Baoqi Yin, Xiaopeng Xing
Atomic oxygen on silver is the crucial active species in many catalytic oxidation processes, while it is a big challenge to explore the relationship between its activity and molecular-level structures in condensed phases. We carried out kinetic measurements of the gas phase reactions between AgnO(-) (n = 1-8) and CO, in which the oxygen atoms were predicted to be terminal ones in AgO(-) and Ag2O(-), in quasi-Ag-O-Ag chains for Ag3O(-) and Ag4O(-), and on the two-fold or three-fold bridging positions in AgnO(-) (n = 5-8)...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27896527/an-enzyme-kinetics-study-of-the-ph-dependence-of-chloride-activation-of-oxygen-evolution-in-photosystem-ii
#13
Sergei Baranov, Alice Haddy
Oxygen evolution by photosystem II (PSII) involves activation by Cl(-) ion, which is regulated by extrinsic subunits PsbQ and PsbP. In this study, the kinetics of chloride activation of oxygen evolution was studied in preparations of PSII depleted of the PsbQ and PsbP subunits (NaCl-washed and Na2SO4/pH 7.5-treated) over a pH range from 5.3 to 8.0. At low pH, activation by chloride was followed by inhibition at chloride concentrations >100 mM, whereas at high pH activation continued as the chloride concentration increased above 100 mM...
November 28, 2016: Photosynthesis Research
https://www.readbyqxmd.com/read/27896020/identification-of-phenolic-secondary-metabolites-from-schotia-brachypetala-sond-fabaceae-and-demonstration-of-their-antioxidant-activities-in-caenorhabditis-elegans
#14
Mansour Sobeh, Esraa ElHawary, Herbenya Peixoto, Rola M Labib, Heba Handoussa, Noha Swilam, Ahmed H El-Khatib, Farukh Sharapov, Tamer Mohamed, Sonja Krstin, Michael W Linscheid, Abdel Nasser Singab, Michael Wink, Nahla Ayoub
BACKGROUND: Schotia brachypetala Sond. (Fabaceae) is an endemic tree of Southern Africa whose phytochemistry and pharmacology were slightly studied. The present work aimed at profiling the major phenolics compounds present in the hydro-alcohol extract from S. brachypetala leaves (SBE) using LC/HRESI/MS/MS and NMR and prove their antioxidant capabilities using novel methods. METHODS: In vitro assays; DPPH, TEAC persulfate decolorizing kinetic and FRAP assays, and in vivo assays: Caenorhabditis elegans strains maintenance, Intracellular ROS in C...
2016: PeerJ
https://www.readbyqxmd.com/read/27886327/in-situ-tem-observation-on-the-interface-type-resistive-switching-by-electrochemical-redox-reactions-at-a-tin-pcmo-interface
#15
Kyungjoon Baek, Sangsu Park, Jucheol Park, Young-Min Kim, Hyunsang Hwang, Sang Ho Oh
The interface-type resistive switching devices exhibiting bipolar and multi-level resistive switching have been considered as the key component for neuromorphic device applications. To directly observe the microscopic details of underlying electrochemical redox reactions occuring at a metal/oxide interface, we implemented in situ resistive switching of TiN/Pr0.7Ca0.3MnO3 (PCMO)/Pt junction devices in a transmission electron microscope (TEM). The in situ TEM observations directly show that an intermediate reaction layer (TiOxNy), growing and shrinking in the thickness range of a few nanometers at the TiN/PCMO interface in response to the applied voltage, mainly determines the device resistance by limiting the transport of charge carriers via the Poole-Frenkel conduction mechanism...
November 25, 2016: Nanoscale
https://www.readbyqxmd.com/read/27883993/stimulation-of-the-nonneuronal-cholinergic-system-by-highly-diluted-acetylcholine-in-keratinocytes
#16
Francesca Uberti, Claudio Bardelli, Vera Morsanuto, Sabrina Ghirlanda, Andrea Cochis, Claudio Molinari
The physiological effects of acetylcholine on keratinocytes depend on the presence of nicotinic and muscarinic receptors. The role of nonneuronal acetylcholine in keratinocytes could have important clinical implications for patients with various skin disorders such as nonhealing wounds. In order to evaluate the efficacy of highly diluted acetylcholine solutions obtained by sequential kinetic activation, we aimed to investigate the effects of these solutions on normal human keratinocytes. Two different concentrations (10 fg/mL and 1 pg/mL) and formulations (kinetically activated and nonkinetically activated) of acetylcholine were used to verify keratinocyte viability, proliferation, and migration and the intracellular pathways involved using MTT, crystal violet, wound healing, and Western blot compared to 147 ng/mL acetylcholine...
November 25, 2016: Cells, Tissues, Organs
https://www.readbyqxmd.com/read/27883312/time-course-analysis-of-gene-expression-during-the-saccharomyces-cerevisiae-hypoxic-response
#17
Nasrine Bendjilali, Samuel MacLeon, Gurmannat Kalra, Stephen D Willis, A K M Nawshad Hossian, Erica Avery, Olivia Wojtowicz, Mark J Hickman
Many cells experience hypoxia, or low oxygen, and respond by dramatically altering gene expression. In the yeast S. cerevisiae, genes that respond are required for many oxygen-dependent cellular processes, such as respiration, biosynthesis and redox regulation. To more fully characterize the global response to hypoxia, we exposed yeast to hypoxic conditions, extracted RNA at different times and performed RNA-seq analysis. Time-course statistical analysis revealed hundreds of genes that changed expression by up to 550-fold...
November 9, 2016: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/27878774/a-model-for-determination-of-operational-conditions-for-successful-shortcut-nitrification
#18
Xiaoguang Liu, Mingu Kim, George Nakhla
Accumulation of nitrite in shortcut nitrification is influenced by several factors including dissolved oxygen concentration (DO), pH, temperature, free ammonia (FA), and free nitrous acid (FNA). In this study, a model based on minimum dissolved oxygen concentration (DOmin), minimum/maximum substrate concentration (Smin and Smax), was developed. The model evaluated the influence of pH (7-9), temperature (10-35 °C), and solids retention time (SRT) (5 days-infinity) on MSC values. The evaluation was conducted either by controlling total ammonium nitrogen (TAN) or total nitrite nitrogen (TNN), concentration at 50 mg N/L while allowing the other to vary from 0 to 1000 mg N/L...
November 23, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27878745/characterization-of-a-marine-microbial-community-used-for-enhanced-sulfate-reduction-and-copper-precipitation-in-a-two-step-process
#19
Octavio García-Depraect, Claudia Guerrero-Barajas, Janet Jan-Roblero, Alberto Ordaz
Marine microorganisms that are obtained from hydrothermal vent sediments present a great metabolic potential for applications in environmental biotechnology. However, the work done regarding their applications in engineered systems is still scarce. Hence, in this work, the sulfate reduction process carried out by a marine microbial community in an upflow anaerobic sludge blanket (UASB) reactor was investigated for 190 days under sequential batch mode. The effects of 1000 to 5500 mg L(-1) of SO4(-2) and the chemical oxygen demand (COD)/SO4(-2) ratio were studied along with a kinetic characterization with lactate as the electron donor...
November 23, 2016: Applied Biochemistry and Biotechnology
https://www.readbyqxmd.com/read/27873068/theoretical-insights-into-nife-hydrogenases-oxidation-resulting-in-a-slowly-reactivating-inactive-state
#20
Raffaella Breglia, Manuel Antonio Ruiz-Rodriguez, Alessandro Vitriolo, Rubén Francisco Gonzàlez-Laredo, Luca De Gioia, Claudio Greco, Maurizio Bruschi
[NiFe]-hydrogenases catalyse the relevant H2 → 2H(+) + 2e(-) reaction. Aerobic oxidation or anaerobic oxidation of this enzyme yields two inactive states called Ni-A and Ni-B. These states differ for the reactivation kinetics which are slower for Ni-A than Ni-B. While there is a general consensus on the structure of Ni-B, the nature of Ni-A is still controversial. Indeed, several crystallographic structures assigned to the Ni-A state have been proposed, which, however, differ for the nature of the bridging ligand and for the presence of modified cysteine residues...
November 21, 2016: Journal of Biological Inorganic Chemistry: JBIC
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