Putative ammonia-oxidizing Crenarchaeota in suboxic waters of the Black Sea : a basin-wide ecological study using 16S ribosomal and functional genes and membrane lipids

Author Posting. © Blackwell, 2007. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Environmental Microbiology 9 (2007): 1001-1016, doi:10.1111/j.1462-2920.2006.01227.x.Within the upper 400 m at western, central, and eastern stations in the world’s largest stratified basin, the Black Sea, we studied the qualitative and quantitative distribution of putative nitrifying Archaea based on their genetic markers (16S rDNA, amoA encoding for the alfa-subunit of archaeal ammonia monooxygenase), and crenarchaeol, the specific glycerol diphytanyl glycerol tetraether (GDGT) of pelagic Crenarchaeota within the Group I.1a. Marine Crenarchaeota were the most abundant Archaea (up to 98% of the total archaeal 16S rDNA copies) in the suboxic layers with oxygen levels as low as 1 μM including layers where previously anammox bacteria were described (Kuypers et al., 2003). Different marine crenarchaeotal phylotypes (both 16S rDNA and amoA) were found at the upper part of the suboxic zone as compared to the base of the suboxic zone and the upper 15-30 m of the anoxic waters with prevailing sulfide concentrations of up to 30 μM. Crenarchaeol concentrations were higher in the sulfidic chemocline as compared to the suboxic zone. These results indicate an abundance of putative nitrifying Archaea at very low oxygen levels within the Black Sea and might form an important source of nitrite for the anammox reaction.This work was supported by a grant from the Netherlands Organization for Scientific Research (VENI Innovational Research Grant nr. 813.13.001 to MJLC), an U. S. National Science Foundation grant OCE0117824 to SGW and the Spinoza award to JSSD, which we greatly acknowledge

The north-eastern Black Sea redox zone hydrochemical structure: observed concentrations and estimated fluxes

peer reviewedThe fine structure of the hydrophysical and hydrochemical parameters observed in the northeastern Black Sea during the 1999-2002 RV ”Akvanavt” cruises is discussed. The observed increase of organic phosphorus and urea at the boundary of oxic and anoxic waters testify that the hydrochmical structure is significantly influenced by chemosynthesis. The calculated nitrogen compound fluxes support the idea that organic nitrogen can be the significant part of total nitrogen in the oxic/anoxic interface

Nanostructured PtZn intermetallic compound: Controlled formation from PtZn(CH₃COO)₄ molecular precursor and tests of catalytic properties

Phase transformations of a newly synthesized heterobimetallic ZnPt(OOCMe)4(H2O)(MeCOOH)2 acetate in a chemically reductive atmosphere at mildly elevated temperatures are thoroughly studied in order to optimize conditions for the formation of nanostructured PtZn intermetallic compound. According to XAFS and XRD data, the first stage of reductive thermolysis is the reduction of the noble metal, while zinc remains in an oxygen environment. At the second stage the reduction of Zn and the formation of the bimetallic solid solution with the fcc lattice occur. It is shown that recrystallization of solid solution to ordered PtZn intermetallic compound with the tetragonal structure occurs in a narrow temperature range of 250–275 °C. Based on these results, the optimum reduction temperature for the preparation of supported bimetallic Pt–Zn/Al2O3 catalyst was determined to be 300 °C. Results of catalytic tests of the supported material are reported

Nanostructured PtZn intermetallic compound: Controlled formation from PtZn(CH3COO)4 molecular precursor and tests of catalytic properties

Phase transformations of a newly synthesized heterobimetallic ZnPt(OOCMe)4(H2O)(MeCOOH)2 acetate in a chemically reductive atmosphere at mildly elevated temperatures are thoroughly studied in order to optimize conditions for the formation of nanostructured PtZn intermetallic compound. According to XAFS and XRD data, the first stage of reductive thermolysis is the reduction of the noble metal, while zinc remains in an oxygen environment. At the second stage the reduction of Zn and the formation of the bimetallic solid solution with the fcc lattice occur. It is shown that recrystallization of solid solution to ordered PtZn intermetallic compound with the tetragonal structure occurs in a narrow temperature range of 250–275 °C. Based on these results, the optimum reduction temperature for the preparation of supported bimetallic Pt–Zn/Al2O3 catalyst was determined to be 300 °C. Results of catalytic tests of the supported material are reported. © 2021 Elsevier Lt

On the Possibility of Aerobic Methane Production by Pelagic Microbial Communities of the Laptev Sea

The taxonomic diversity and metabolic activity of microbial communities in the Laptev Sea water column above and outside the methane seep field were studied. The concentrations of dissolved methane in the water column at both stations were comparable until the depth of the pycnocline (25 m). At this depth, local methane maxima were recorded, with the highest concentration (116 nM CH4) found at the station outside the methane seep field. Results of the 16S rRNA gene sequencing and measurements of the rates of hydrogenotrophic methanogenesis indicated the absence of methanogenesis caused by the methanogenic archaea in the pycnocline and in other horizons of the water column. The 16S rRNA-based analysis of microbial phylogenetic diversity, as well as radiotracer analysis of the rates of primary production (PP), dark CO2 assimilation (DCA), and methane oxidation (MO), indicated the functioning of a diverse community of pelagic microorganisms capable of transforming a wide range of organic compounds under oligotrophic conditions of the Arctic basin. Hydrochemical prerequisites and possible microbial agents of aerobic methane production via demethylation of methylphosphonate and decomposition of dimethylsulfoniopropionate using dissolved organic matter synthesized in the PP, DCA, and MO processes are discussed

Structural transformation during melting of cast 10R6M5 steel powder

22.00; Translated from Russian (Izv. Vyssh. Uchebn. Chern. Metall. 1986 (6) p. 91-96)SIGLEAvailable from British Library Document Supply Centre- DSC:9022.06(BISI--25312)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The First Heterometallic Acetate-Bridged Pt(II)–Pd(II) Complex: Synthesis, Structure, and Formation of Bimetallic PtPd 2 Nanoparticles

Abstract: The reaction of platinum acetate blue, empirically described as Pt(OOCMe) 2.50 , with palladium(II) acetate Pd 3 (μ-OOCMe) 6 gave the first heterometallic acetate-bridged platinum(II) and palladium(II) complex Pd 2 Pt(μ-OOCMe) 6 (I) as co-crystallizates 17Pd 2 Pt(μ-OOCMe) 6 ⋅ 4Pd 3 (μ-OOCMe) 6 ⋅ 42C 6 H 6 (IIa) and 17Pd 2 Pt(μ-OOCMe) 6 ⋅ 4 Pd 3 (μ-OOCMe) 6 (IIb). Single crystal X-ray diffraction (CIF files CCDC nos. 1568105 and 1852744), EXAFS, and quantum chemical studies (DFT and QTAIM) of complex I revealed a slightly distorted triangular structure similar to the structure of palladium(II) acetate Pd 3 (μ-OOCMe) 6 and hypothetical platinum(II) complex Pt 3 (μ-OOCMe) 6 . The thermal decomposition of complex IIa gives the bimetallic alloy PtPd 2 . A combined X-ray diffraction and EXAFS study demonstrated that the obtained material consists of core (Pt)–shell (Pd) particles with an average size of ~28 nm and a minor amount of smaller (~5 nm) PdO nanoparticles on the surface. The obtained results are useful for the understanding of the nature and structure of the supported phase of heterogeneous Pt–Pd catalysts. © 2019, Pleiades Publishing, Ltd

Heterometallic Palladium(II)-Indium(III) and -Gallium(III) Acetate-Bridged Complexes: Synthesis, Structure, and Catalytic Performance in Homogeneous Alkyne and Alkene Hydrogenation

The reaction of Pd3(OOCMe)6 with indium(III) and gallium(III) acetates was studied to prepare new PdII-based heterometallic carboxylate complexes with group 13 metals. The heterometallic palladium(II)-indium(III) acetate-bridged complexes Pd(OOCMe)4In(OOCMe) (1) and Pd(OOCMe)4In(OOCMe)·MeCOOH (1a) were synthesized and structurally characterized with X-ray crystallography and extended X-ray absorption fine structure in the solid state and solution. A similar Pd-Ga heterometallic complex formed by the reaction of Pd3(OOCMe)6 with gallium(III) acetate in a dilute acetic acid solution, as evidenced by atmospheric pressure chemical ionization mass and UV-vis spectrometry, was unstable at higher concentrations and in the solid state. Complex 1 catalyzes the liquid-phase-selective phenylacetylene and styrene hydrogenation (1 atm of H2 at 20 °C) in acetic acid, ethyl acetate, and N,N-dimethylformamide solutions, while no Pd metal was formed until alkyne and alkene hydrogenation ceased. © 2018 American Chemical Society