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Sujith Kakkattu S, Chelat Narayana Panicker Ramachandran
Natural gas extraction from gas hydrate sediments by injection of hydrate inhibitors involves the decomposition of hydrates. The evolution of dissolved gas from the hydrate melt is an important step in the extraction process. Using classical molecular dynamics simulations, we study the evolution of dissolved methane from its hydrate melt in presence of two thermodynamic hydrate inhibitors, NaCl and CH3OH. An increase in the concentration of hydrate inhibitors is found to promote the nucleation of methane nanobubbles in the hydrate melt...
December 9, 2016: Journal of Physical Chemistry. B
Sepehr Mohammadi, Arjan Pol, Theo A van Alen, Mike Sm Jetten, Huub Jm Op den Camp
Methanotrophs play a key role in balancing the atmospheric methane concentration. Recently, the microbial methanotrophic diversity was extended by the discovery of thermoacidophilic methanotrophs belonging to the Verrucomicrobia phylum in geothermal areas. Here we show that a representative of this new group, Methylacidiphilum fumariolicum SolV, is able to grow as a real 'Knallgas' bacterium on hydrogen/carbon dioxide, without addition of methane. The full genome of strain SolV revealed the presence of two hydrogen uptake hydrogenases genes, encoding an oxygen-sensitive (hup-type) and an oxygen-insensitive enzyme (hhy-type)...
December 9, 2016: ISME Journal
Giovanni Ribaudo, Massimo Bellanda, Ileana Menegazzo, Lando Peter Wolters, Marco Bortoli, Gerardo Ferrer-Sueta, Giuseppe Zagotto, Laura Orian
The oxidation of organic phenylselenides by H₂O₂ is investigated in model compounds, i.e. n-butyl phenyl selenide (PhSe(n-Bu)), bis(phenylselanyl)methane (PhSeMeSePh), diphenyl diselenide (PhSeSePh) and 1,2-bis(phenylselanyl)ethane (PhSeEtSePh). Through a combined experimental (¹H and ⁷⁷Se NMR) and computational approach, we characterize the direct oxidation of monoselenide to selenoxide, the stepwise double oxidation of PhSeMeSePh leading to different diastereomeric diselenoxides, the complete oxidation of the diphenyldiselenide leading to selenium-selenium bond cleavage and subsequent formation of the phenylseleninic product...
December 9, 2016: Chemistry: a European Journal
Andrew W Cook, Thuy-Ai D Nguyen, William R Buratto, Guang Wu, Trevor W Hayton
The group 11 hydride clusters [Ag6H4(dppm)4(OAc)2] (1) and [Cu3H(dppm)3(OAc)2] (2) (dppm = 1,1-bis(diphenylphosphino)methane) were synthesized in moderate yields from the reaction of M(OAc) (M = Ag, Cu) with Ph2SiH2, in the presence of dppm. Complex 1 is the first structurally characterized homometallic polyhydrido silver cluster to be isolated. Both 1 and 2 catalyze the hydrosilylation of (α,β-unsaturated) ketones. Notably, this represents the first example of hydrosilylation with an authentic silver hydride complex...
December 5, 2016: Inorganic Chemistry
Neena Chakrabarti, Serge Ruccolo, Gerard Parkin
Tris(2-pyridylthio)methane ([Tptm]H) has been employed to synthesize a series of cadmium carbatrane compounds that feature an [N3C] coordination environment. Specifically, [Tptm]H reacts with Cd[N(SiMe3)2]2 to afford [Tptm]CdN(SiMe3)2, which thereby provides access to other derivatives. For example, [Tptm]CdN(SiMe3)2 reacts with (i) CO2 to form {[Tptm]Cd(μ-NCO)}2 and (ii) Me3SiOH and Ph3SiOH to form {[κ(3)-Tptm]Cd(μ-OSiMe3)}2 and [Tptm]CdOSiPh3, respectively. The siloxide compound {[κ(3)-Tptm]Cd(μ-OSiMe3)}2 reacts with Me3SiX (X = Cl, Br, O2CMe) to give [Tptm]CdX, while the reaction with PhSiH3 in the presence of CO2 generates the formate complex, [Tptm]CdO2CH, thereby providing evidence for the generation of a proposed cadmium hydride intermediate, {[Tptm]CdH}...
December 5, 2016: Inorganic Chemistry
Joannes D Maasakkers, Daniel J Jacob, Melissa P Sulprizio, Alexander J Turner, Melissa Weitz, Tom Wirth, Cate Hight, Mark DeFigueiredo, Mausami Desai, Rachel Schmeltz, Leif Hockstad, Anthony A Bloom, Kevin W Bowman, Seongeun Jeong, Marc L Fischer
We present a gridded inventory of US anthropogenic methane emissions with 0.1° × 0.1° spatial resolution, monthly temporal resolution, and detailed scale-dependent error characterization. The inventory is designed to be consistent with the 2016 US Environmental Protection Agency (EPA) Inventory of US Greenhouse Gas Emissions and Sinks (GHGI) for 2012. The EPA inventory is available only as national totals for different source types. We use a wide range of databases at the state, county, local, and point source level to disaggregate the inventory and allocate the spatial and temporal distribution of emissions for individual source types...
December 6, 2016: Environmental Science & Technology
Ke Chen, Shiwen Wu, Lu Zhu, Chengde Zhang, Wensheng Xiang, Zixin Deng, Haruo Ikeda, David E Cane, Dongqing Zhu
In the biosynthesis of pentalenolactone (1), PenE and PntE, orthologous proteins from Streptomyces exfoliatus and S. arenae, respectively, catalyze the flavin-dependent Baeyer-Villiger oxidation of 1-deoxy-11-oxopentalenic acid (4) to the lactone pentalenolactone D (5), in which the less-substituted methylene carbon has migrated. By contrast, the paralogous PtlE enzyme from S. avermitilis catalyzes the oxidation of 4 to neopentalenolactone D (6), in which the more substituted methane substitution has undergone migration...
December 6, 2016: Biochemistry
Yuan Liu, Xiaoyu Liu, Kun Cheng, Lianqing Li, Xuhui Zhang, Jufeng Zheng, Jinwei Zheng, Genxing Pan
Although climate change is predicted to affect methane (CH4) emissions in paddy soil, the dynamics of methanogens and methanotrophs in paddy fields under climate change have not yet been fully investigated. To address this issue, a multifactor climate change experiment was conducted in a Chinese paddy field using the following experimental treatments: (1) enrichment of atmospheric CO2 concentrations (500 ppm, CE), (2) canopy air warming (2°C above the ambient, WA), (3) combined CO2 enrichment and warming (CW), and (4) ambient conditions (CK)...
2016: Frontiers in Microbiology
Joy Buongiorno, Jordan T Bird, Kirill Krivushin, Victoria Oshurkova, Victoria Shcherbakova, Elizaveta M Rivkina, Karen G Lloyd, Tatiana A Vishnivetskaya
A genomic reconstruction belonging to the genus Methanosarcina was assembled from metagenomic data from a methane-producing enrichment of Antarctic permafrost. This is the first methanogen genome reported from permafrost of the Dry Valleys and can help shed light on future climate-affected methane dynamics.
December 8, 2016: Genome Announcements
Panagiotis G Kougias, Laura Treu, Daniela Peñailillo Benavente, Kanokwan Boe, Stefano Campanaro, Irini Angelidaki
Biogas upgrading is envisioned as a key process for clean energy production. The current study evaluates the efficiency of different reactor configurations for ex-situ biogas upgrading and enhancement, in which externally provided hydrogen and carbon dioxide were biologically converted to methane by the action of hydrogenotrophic methanogens. The methane content in the output gas of the most efficient configuration was >98%, allowing its exploitation as substitute to natural gas. Additionally, use of digestate from biogas plants as a cost efficient method to provide all the necessary nutrients for microbial growth was successful...
December 2, 2016: Bioresource Technology
Bahar Ahoughalandari, Alexandre R Cabral
The efficiency of methane oxidation in passive methane oxidation biosystems (PMOBs) is influenced by, among other things, the intensity and distribution of the CH4 loading at the base of the methane oxidation layer (MOL). Both the intensity and distribution are affected by the capillary barrier that results from the superposition of the two materials constituting the PMOB, namely the MOL and the gas distribution layer (GDL). The effect of capillary barriers on the unsaturated flow of water has been well documented in the literature...
December 5, 2016: Waste Management
Camille Baccot, Virginie Pallier, Geneviève Feuillade-Cathalifaud
Many data on anaerobic digestion (AD) and co-digestion of municipal solid waste leachate (MSWL) are already available in literature. They mainly deal with its performances to decrease the chemical oxygen demand (COD) of MSWL and no information is given on the impact of the specific characteristics of the dissolved organic matter (DOM) in leachate on these performances. DOM in leachate evolves towards more aromatic and hydrophobic compounds during landfilling with increasing specific ultra-violet absorbance index (SUVA) and hydrophobic character...
December 5, 2016: Waste Management
Xuan Cheng, Lu Zhang, Nan-Chang Xie, Hong-Liang Xu, Ya-Jun Lian
BACKGROUND: Gastrointestinal dysfunction and vein thrombosis are well-known acute complications after spinal cord injuries (SCI). OBJECTIVE: The aim of this study was to determine the frequency and risk factors for deep vein thrombosis (DVT) and small intestinal bacterial overgrowth (SIBO) in patients with SCI. METHODS: A total of 377 consecutive eligible patients with SCI tested for SIBO using glucose hydrogen (H2)/methane(CH4) breath test from January 2011 to December 2015 and who also had venous ultrasound study for suspected DVT were evaluated within 3 months after admission...
December 8, 2016: Journal of Thrombosis and Haemostasis: JTH
Xin Xu, Zhen Wu, Yubing Dong, Ziqiang Zhou, Zhengqin Xiong
The CH4 emissions from soil were influenced by the changeable CH4 concentrations and diffusions in soil profiles, but that have been subjected to nitrogen (N) and biochar amendment over seasonal and annual time frames. Accordingly, a two-year field experiment was conducted in southeastern China to determine the amendment effects on CH4 concentrations and diffusive effluxes as measured by a multilevel sampling probe in paddy soil during two cycles of rice-wheat rotations. The results showed that the top 7-cm soil layers were the primary CH4 production sites during the rice-growing seasons...
December 8, 2016: Scientific Reports
Yuan-Zhu Zhang, Silvia Gómez-Coca, Andrew J Brown, Mohamed R Saber, Xuan Zhang, Kim R Dunbar
The air-stable mononuclear Co(ii) compounds [Co(II)(Tpm)2][ClO4]2 (1, Tpm = tris(pyrazol-1-yl)methane), [Co(II)(Tpm)2][BPh4]2·2MeCN (2) with trigonal antiprismatic geometry (trigonally elongated octahedral geometry) are reported. Magnetic and theoretical studies reveal that the complexes exhibit single-molecule magnet behavior with uniaxial anisotropy and a huge energy difference between ground and first excited Karmers' doublets (∼200 cm(-1)). Under applied DC fields, compounds 1 and 2 exhibit frequency and temperature dependence of the imaginary susceptibility...
October 19, 2016: Chemical Science
Bhagwan Shamrao Patil, Agnes Anto C, Devendra Narain Singh
Municipal solid waste generation is huge in growing cities of developing nations such as India, owing to the rapid industrial and population growth. In addition to various methods for treatment and disposal of municipal solid waste (landfills, composting, bio-methanation, incineration and pyrolysis), aerobic/anaerobic bioreactor landfills are gaining popularity for economical and effective disposal of municipal solid waste. However, efficiency of municipal solid waste bioreactor landfills primarily depends on the municipal solid waste decomposition rate, which can be accelerated through monitoring moisture content and temperature by using the frequency domain reflectometry probe and thermocouples, respectively...
December 6, 2016: Waste Management & Research
Jie Xu, Ahmed M Mustafa, Kuichuan Sheng
To overcome the biogas inhibition in anaerobic digestion of fish waste (FW), effects of inoculum to substrate (I/S, based on VS) and co-digestion with bagasse on biogas production of fish waste were studied in batch reactors. I/S value was from 0.95 to 2.55, bagasse content in co-digestion (based on VS) was 25%, 50%, 75%. The highest biogas yield (433.4 mL/gVS) with 73.34% methane content was obtained at I/S value of 2.19 in mono-digestion of FW, the biogas production was inhibited and the methane content was below 70% when I/S was below 1...
December 7, 2016: Environmental Technology
D E Holmes, J A Smith
Methanogens are a unique group of strictly anaerobic archaea that are more metabolically diverse than previously thought. Traditionally, it was thought that methanogens could only generate methane by coupling the oxidation of products formed by fermentative bacteria with the reduction of CO2. However, it has recently been observed that many methanogens can also use electrons extruded from metal-respiring bacteria, biocathodes, or insoluble electron shuttles as energy sources. Methanogens are found in both human-made and natural environments and are responsible for the production of ∼71% of the global atmospheric methane...
2016: Advances in Applied Microbiology
Hanno Schmiedt, Per Jensen, Stephan Schlemmer
The concept of molecular structure is traditionally considered to be virtually fundamental. However, it breaks down in extremely flexible molecules, whose dynamics are governed by large-amplitude motions. For the dynamics of molecules with free internal rotations, we therefore propose a five-dimensional rigid rotor model, with states characterized by two generalized angular momentum quantum numbers and a rotational constant B. The quantum numbers characterize a 5D angular-momentum vector, super-j, which describes collective rotations that involve both the internal and the overall rotation...
November 25, 2016: Physical Review Letters
Erin E Duffy, Matthew D Simon
Metabolic labeling of cellular RNA is a useful approach to study RNA biology. 4-Thiouridine (s(4) U) is a convenient nucleoside for metabolic labeling because it is cell permeable and is incorporated into newly transcribed RNA, and the sulfur moiety provides a handle for biochemical purification. However, a critical step in the purification of s(4) U-RNA is the efficiency of the chemistry used to enrich s(4) U-RNA. Here, we present a protocol for s(4) U-RNA enrichment that includes efficient and reversible covalent chemistry to biotinylate s(4) U-RNA using the activated disulfide methane thiosulfonate conjugated to biotin (MTS-biotin), followed by enrichment on streptavidin beads...
December 7, 2016: Current Protocols in Chemical Biology
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