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Simultaneous nitrification and autotrophic denitrification in fluidized bed reactors using pyrite and elemental sulfur as electron donors

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Water Science and Engineering 2023年第2期16卷 143-153页

作者： maria f.carboni Sonia Arriaga Piet N.L.Lens National University of Ireland Galway H91 TK33 GalwayIreland Instituto Potosino de Investigación Científica y Tecnológica 78216 San Luis PotosíMexico

In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was evaluated at different ammonium (12-40 mg/L of NH4+-N), nitrate (35-45 mg/L of NO3--N), and dissolved oxygen (DO) (0.1-1.5 mg/L) concentrations, with a hydraulic retention time of 12 h. The pyrite reactor supported the SNAD process with a maximum nitrogen removal efficiency of 139.5 mg/(L·d) when the DO concentration was in the range of 0.8-1.5 mg/L. This range, however, limited the denitrification efficiency of the reactor, which decreased from 90.0% ± 5.3% in phases II-V to 67.9% ± 7.2% in phases VI and VII. Sulfate precipitated as iron sulfate (feSO4/fe2(SO4)3) and sodium sulfate (Na2SO4) minerals during the experiment. The sulfur reactor did not respond well to nitrification with a low and unstable ammonium removal efficiency, while denitrification occurred with a nitrate removal efficiency of 97.8%. In the pyrite system, the nitrifying bacterium Nitrosomonas sp. was present, and its relative abundance increased from 0.1% to 1.1%, while the autotrophic denitrifying genera Terrimonas, ferruginibacter, and Denitratimonas dominated the community. Thiobacillus, Sulfurovum, and Trichlorobacter were the most abundant genera in the sulfur reactor during the entire experiment.

关键词： Pyrite Elemental sulfur Simultaneous nitrification and denitrification Nitrogen removal 16S rRNA

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Protein tyrosine phosphorylation of the human sperm head during capacitation： immunolocalization and relationship with acquisition of sperm-fertilizing ability

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Asian Journal of Andrology 2010年第6期12卷 853-861页

作者： Arcangelo Barbonetti maria Rosaria C. Vassallo Giuliana Cordeschi Dimitrios Venetis Andrea carboni Alessandra Sperandio Giorgio felzani Sandro francavilla felice francavilla Andrology Unit Department of Internal Medicine University of L＇Aquila Coppito 67100 L＇Aquila Italy Istituto di Ricovero e Cura a Carattere Scientifico S.Raffaele Sulmona 67039 Italy

The occurrence of tyrosine phosphorylation （TP） in the sperm head during capacitation has been poorly investigated, and no data exist on the relationship of its dynamics with the acquisition of sperm fertilizing ability. This study localized TP of head proteins in human spermatozoa during capacitation and explored its relationship with acquisition of the ability to display progesterone （P）-stimulated acrosome reactions （ARs） and to penetrate zona-free hamster oocytes. By immunofluorescence, TP immunoreactivity was revealed in the acrosomal region of formaldehyde-fixed/unpermeabilized samples, whereas it was abolished in fixed/permeabilized samples, in which TP immunoreactivity was high in the principal piece. No TP immunoreaetivity was detectable in unfixed spermatozoa. Head TP immunoreactivity was localized externally to the acrosome, close to the cytoplasmic membrane, as assessed by transmission electron microscopy. The increase in head TP was an early event during capacitation, occurring within 1 h in capacitating conditions. At this time, the P-stimulated ARs were also increased, whereas egg penetration was as poor as in uncapacitated spermatozoa. At 5 h of capacitation, the extent of neither head TP nor the P-induced ARs were greater than that at 1 h, whereas egg penetration had significantly increased. Seminal plasma inhibited head TP, P-induced ARs and egg penetration. None of these inhibitory effects, unlike those on tail TP, were prevented by the cAMP analogue dbcAMP （N,2-O-dibutyryladenosine 3＇,5＇-cyclic monophosphate）. In conclusion, head TP is a subsurface event occurring early during capacitation and is closely related to acquisition of the ability to display P-stimulated ARs, whereas the ability to fuse with oolemma and to decondense is a later capacitation-related event.

关键词： acrosome reaction capacitation human spermatozoa sperm-oocyte fusion tyrosine phosphorylation

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