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Oxygen kinetics

Annamaria Ricciardi, Rocco Gerardo Ianniello, Eugenio Parente, Teresa Zotta
Catalases reduce oxidative stress by degrading hydrogen peroxide to molecular oxygen and water. The presence of heme-dependent or manganese-dependent catalases was observed for a long time in lactic acid bacteria (LAB) but, to date, knowledge on the factors affecting gene expression and enzymatic functionality are limited to a very few strains. In this study, the effect of atmosphere of incubation (not aerated static growth vs aerated shaken growth) and supplementation with Fe2+ , hemin, Mn2+ or their combinations on the catalase production of respiration-competent strain Lactobacillus casei N87 was evaluated using a 24 factorial design...
May 8, 2018: International Journal of Food Microbiology
Nemanja Anicˇić, Marija Vukomanović, Tilen Koklicˇ, Danilo Suvorov
Magnesium oxide (MgO) is recognised as exhibiting a contact-based antibacterial activity. However, a comprehensive study of the impact of atomic-scale surface features on MgO's antibacterial activity is lacking. In this study, the nature and abundance of the native surface defects on different MgO powders are thoroughly investigated. Their impacts on the hydrolysis kinetics, antibacterial activity against Escherichia coli (ATCC 47076), Staphylococcus epidermidis and Pseudomonas aeruginosa and the reactive oxygen species (ROS) generation potential are determined and explained...
May 21, 2018: Small
Matthias Gilbert, Hanno Bährs, Christian E W Steinberg, Christian Wilhelm
Humic substances (HSs) can influence the growth and composition of freshwater phytoplankton assemblage. Since HSs contain many phenolic and quinonic moieties and cause growth reductions in eco-physiological field experiments, HSs are considered photosystem II herbicides. To test this specific mode of action in vivo and in vitro, respectively, we used intact cells of the green alga Desmodesmus armatus, as well as thylakoids isolated from spinach (Spinacia oleracea) as a model system for the green algal chloroplast...
May 18, 2018: Photosynthesis Research
Byeongho Park, Heehong Yang, Tai Hwan Ha, Hyun Seo Park, Seung Ja Oh, Yong-Sang Ryu, Youngho Cho, Hyo-Suk Kim, Juyeong Oh, Dong Kyu Lee, Chulki Kim, Taikjin Lee, Minah Seo, Jaebin Choi, Young Min Jhon, Deok Ha Woo, Seok Lee, Seok Hwan Kim, Hyuk-Jae Lee, Seong Chan Jun, Hyun Seok Song, Tai Hyun Park, Jae Hun Kim
Photosensitive materials contain biologically engineered elements and are constructed using delicate techniques, with special attention devoted to efficiency, stability, and biocompatibility. However, to date, no photosensitive material has been developed to replace damaged visual-systems to detect light and transmit the signal to a neuron in the human body. In the current study, artificial nanovesicle-based photosensitive materials are observed to possess the characteristics of photoreceptors similar to the human eye...
May 18, 2018: Advanced Materials
Vidar Skaug, Einar Eilertsen, Asbjørn Skogstad, Finn E S Levy, Balázs Berlinger, Yngvar Thomassen, Dag G Ellingsen
INTRODUCTION: Shotgun pellets containing bismuth (Bi) as substitute for lead (Pb) are increasingly being used due to environmental concerns. Information on toxicokinetics of Bi is lacking for the assessment of humans accidentally shot by Bi-containing shotgun alloy pellets. METHODS: Male Wistar rats were exposed to miniature alloy pellets containing Bi, tin (Sn) and minor amounts of Pb by implantation in muscle tissues of the hind legs. RESULTS: The concentrations of Bi in whole blood and urine increased up to 53 weeks after implantation...
July 2018: Journal of Trace Elements in Medicine and Biology
Tobias Michael Hedison, Sam Hay, Nigel Shaun Scrutton
The three mammalian isoforms of nitric oxide synthase (NOS) produce the signalling molecule nitric oxide (NO) from L-arginine, molecular oxygen, and NADPH. NOS-generated NO is essential for many key biochemical processes and aberrant NO production is linked to the pathophysiology of many diseases. Over the past 40 years, the mechanism and structure of NOS have been studied extensively and there are many quality reviews and perspectives documenting the current hypotheses in the field. In this review, as an alternative perspective, we will describe some novel techniques and methodologies that have been used to trap functionally relevant conformational and kinetic states in the catalytic cycles of NOS and some structurally related diflavin oxidoreductase...
June 1, 2018: Frontiers in Bioscience (Landmark Edition)
Ying Shi, Li Liu, Yuanyuan Yu, Yijuan Long, Huzhi Zheng
Nanomaterials have triggered tremendous interest to mimick peroxidase but rarely attention has been paid to small molecules. Herein we first found that acidic amino acids including l-glutamic acid (L-Glu) and l-aspartic acid (L-Asp) exhibited an intrinsic peroxidase-like activity, endowing acidic amino acids with the capability of catalysing the oxidation of the peroxidase substrates 3,3',5,5'-tetramethylbenzidine (TMB) to produce color reaction in the presence of H2 O2 . Reaction mechanism was further investigated by means of electron spin resonance spectroscopy (ESR), enzyme kinetics assay and quantum theoretical calculations, to verify and provide a good deal of insight into the catalytic process...
May 8, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Imran Ali, Omar M L Alharbi, Zeid A Alothman, Ahmad Yacine Badjah
Titanium oxide nanoparticles were doped with copper and characterized by XRD, FT-IR, TEM and SEM. The surface morphology was spherical with 15-26 nm as particle size. The doped titanium oxide (Co/TiO2 ) nanomaterial was used for photodegradation of amido black dye in water. The maximum photodegradation of amido black obtained was 90%. The values of free energy, and enthalpy were negative, indicating spontaneous photodegradation of amido black dye. The photodegradation of amido black dye obeyed first order kinetic model...
May 16, 2018: Photochemistry and Photobiology
Yanzhou Wang, Panpan Gao, Xiaoxu Wang, Jinrong Huo, Lu Li, Yajing Zhang, Alex A Volinsky, Ping Qian, Yanjing Su
The pursuit of catalysts to promote effective water oxidization to produce oxygen has become a research subject of high priority for water splitting. Here, first-principles calculations are employed to study the water-splitting oxygen evolution reaction (OER) on ∼1.5 nm diameter Au13@Ni120P50 core-shell nanoclusters. Water splitting to produce oxygen proceeds in four intermediate reaction steps (OH*, O*, OOH* and O2). Adsorption configurations and adsorption energies for the species involved in OER on both Au13@Ni120P50 cluster and Ni12P5(001) supported by Au are presented...
May 16, 2018: Physical Chemistry Chemical Physics: PCCP
Meizhen Tang, Zhengtao Li, Yuewei Yang, Junfeng Chen, Jie Jiang
Constructed wetlands (CWs) have been used globally in wastewater treatment for years. CWs represent an efficient ecological system which is both energy-saving and low in investment for construction and operational cost. In addition, CWs also have the advantage of being easy to operate and maintain. However, the operation of CWs at northern latitudes (both mid and high) is sometimes quite demanding, due to the inhibitory effect of low temperatures that often occur in winter. To evaluate the wastewater treatment performance of a culture of mixed Psychrotrophic bacteria strains in an integrated vertical-flow CW, the removal rates of ammonia nitrogen (NH3 -N), chemical oxygen demand (COD), nitrite nitrogen [Formula: see text], nitrate nitrogen [Formula: see text] and total phosphorus (TP) were quantified at different bacterial dosages to determine the best bacterial dosage and establish kinetic degradation models of the mixed strains...
April 2018: Royal Society Open Science
P Rahul, K Prasanna, Prosenjit Ghosh, N Anilkumar, Kei Yoshimura
Stable Hydrogen and Oxygen isotopic composition of water vapor, rainwater and surface seawater show a distinct trend across the latitude over the Southern Indian Ocean. Our observations on isotopic composition of surface seawater, water vapor and rainwater across a transect covering the tropical Indian Ocean to the regions of the Southern Ocean showed a strong latitudinal dependency; characterized by the zonal process of evaporation and precipitation. The sampling points were spread across diverse zones of SST, wind speed and rainfall regimes...
May 15, 2018: Scientific Reports
Rui Li, Yu Jiang, Beidou Xi, Mingxiao Li, Xiaoguang Meng, Chuanping Feng, Xuhui Mao, Hongliang Liu, Yonghai Jiang
Microorganisms from paddy soils and raw hematite are used for enhancing natural Fe(III) bio-reduction, in order to remove macromolecular organic pollutants from humified landfill leachate. Based on batch experiments, 60% of refractory organics can be adsorbed by hematite in 12 days. In the presence of Fe(III)-reducing bacteria, 489.60 ± 0.14 mg L-1 of dissolved organic matters can be degraded to 51.90 ± 3.96 mg L-1 within 50 days; twelve types of semi volatile organic compounds can be degraded; hereby, the reaction follows a first-order kinetics...
May 3, 2018: Journal of Hazardous Materials
Bo You, Guanqun Han, Yujie Sun
Renewable energy-driven hydrogen production from electrocatalytic and photocatalytic water splitting has been widely recognized as a promising approach to utilize green energy resources and hence reduces our dependence on legacy fossil fuels as well as alleviates net carbon dioxide emissions. The realization of large-scale water splitting, however, is mainly impeded by its slow kinetics, particularly because of its sluggish anodic half reaction, the oxygen evolution reaction (OER), whose product O2 is ironically not of high value...
May 15, 2018: Chemical Communications: Chem Comm
Yongchao Chi, Junjie Xue, Jiankun Zhuo, Dahu Zhang, Mi Liu, Qiang Yao
Fast pyrolysis is one of the most economical and efficient technologies to convert biomass to bio-oil and valuable chemical products. Co-pyrolysis with hydrogen rich materials such as plastics over zeolite catalysts is one of the significant solutions to various problems of bio-oil such as high oxygen content, low heat value and high acid content. This paper studied pyrolysis of cellulose and polypropylene (PP) separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41. The pyrolysis over different heating rates (10K/min, 20K/min, 30K/min) was studied by Thermogravimetry Analysis (TGA) and kinetic parameters were obtained by Coats-Redfern method and isoconversion method...
August 15, 2018: Science of the Total Environment
Sergio Colangiuli, Ana Rodríguez, María Ángeles Sanromán, Francisco J Deive
The definition of halophiles as "the coming stars of industrial biotechnology" in a recent review demands new research efforts for their efficient production at bioreactor scale. In this sense, the scarcity of information about halolipases production has furthered the research on the viability of Halomonas sp. LM1C culture in a mechanically stirred bioreactor. The operating conditions have been optimized by means of a Central Composite Face-Centered (CCFC) design. The operation at low aerations (0...
May 4, 2018: Bioresource Technology
Dejana Popovic, Nikhil Kumar, Sundeep Chaudhry, Akshay Bagai, Ross Arena, Naresh Kumar
PURPOSE: Improvements in cardiorespiratory fitness (VO2peak) post-cardiac rehabilitation (post-CR) are used to gauge therapeutic efficacy. The aim of the present study was to assess the effect of supervised CR on other cardiopulmonary exercise testing (CPX) variables, specifically those that reflect ventilatory efficiency and VO2 changes in relation to changes in work rate (WR). METHODS: Patients (n = 142; mean age 63 ± 9 y; 23% female) with coronary artery disease (CAD) participated in supervised CR for 3 to 6 mo completing 60 ± 17 sessions (range: 32-96 sessions), with intensity derived from the baseline CPX...
May 11, 2018: Journal of Cardiopulmonary Rehabilitation and Prevention
S W How, S Y Lim, P B Lim, A M Aris, G C Ngoh, T P Curtis, A S M Chua
Intensive aeration for nitrification is a major energy consumer in sewage treatment plants (STPs). Low-dissolved-oxygen (low-DO) nitrification has the potential to lower the aeration demand. However, the applicability of low-DO nitrification in the tropical climate is not well-understood. In this study, the potential of low-DO nitrification in tropical setting was first examined using batch kinetic experiments. Subsequently, the performance of low-DO nitrification was investigated in a laboratory-scale sequential batch reactor (SBR) for 42 days using real tropical sewage...
May 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Andrea Benáková, Iva Johanidesová, Petr Kelbich, Vojtěch Pospíšil, Jiří Wanner
This work focuses on the removal of ammonia nitrogen pollution from wastewaters in a two-stage laboratory model based on a combination of the nitritation and anammox processes with the biomass immobilized in a polyvinyl alcohol (PVA) matrix. Owing to the immobilization approach inside the PVA pellets, the bacterial activity remained nearly unchanged on an abrupt change in the environmental conditions. The nitritation kinetics were significantly dependent on the dissolved oxygen concentration. The critical dissolved oxygen concentration at which the nitritation process using the immobilized bacterial culture stops is 0...
May 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Bo Shen, Xianghua Wen, Gregory V Korshin
Herein, the rotating disk electrode technique was used for the first time to investigate the effects of mass-transfer limitations and pH on the electrochemical oxidation of CPX, to determine the kinetics of CPX oxidation and to explore intrinsic mechanisms during the electron transfer process. Firstly, cyclic voltammetry revealed that an obvious irreversible CPX oxidation peak was observed within the potential window from 0.70 to 1.30 V at all pHs. Based on the Levich equation, the electrochemical oxidation of CPX in the electron transfer process was found to be controlled by both diffusion and kinetic processes when pH = 2, 5, 7 and 9; the diffusion coefficient of CPX at pH = 2 was calculated to be 1...
May 14, 2018: Environmental Science. Processes & Impacts
Hongyan Li, Pei Gao, Jianguo Cui, Feng Zhang, Fang Wang, Jici Cheng
Corncob activated carbon (CCAC) was prepared by a H3 PO4 activation method. The optimum conditions for the preparation of CCAC were determined by orthogonal experiments. The effects of pH, reaction time, CCAC dosage, and hexavalent chromium (Cr(VI)) concentrations on Cr(VI) removal by CCAC were studied. Corn straw activated carbon (CSAC) was also prepared using the optimum preparation conditions determined for CCAC. The properties of samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS)...
May 12, 2018: Environmental Science and Pollution Research International
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