The matrix conversion of natural gas into synthesis gas, in which the autothermal oxidation occurs in the surface combustion mode in a cavity of a closed three-dimensional matrix made of a ...gas-permeable material, was studied experimentally. The specific volumetric productivity of such converters considerably exceeds that of traditional types of converters and allows conversion of hydrocarbon gases of virtually any composition into synthesis gas. Prospects for practical use of the new type of converters are discussed.
Two already known representatives of Holospora-like bacteria, “Candidatus Gortzia yakutica” from Paramecium putrinum and Preeria caryophila, originally retrieved from the Paramecium aurelia complex, ...were found in new hosts: Paramecium nephridiatum and Paramecium polycaryum, respectively. In the present study, these bacteria were investigated using morphological and molecular methods. For “Ca. G. yakutica”, the first details of the electron microscopic structure in the main and new hosts were provided. Regarding Pr. caryophila, the ultrastructural description of this species was implemented by several features previously unknown, such as the so called “membrane cluster” dividing periplasm from cytoplasm and fine composition of infectious forms before and during its releasing from the infected macronucleus. The new combinations of these Holospora-like bacteria with ciliate hosts were discussed from biogeographical and ecological points of view. Host specificity of symbionts as a general paradigm was critically reviewed as well.
Different variants of preconditioning of wet and associated petroleum gases and controlling the characteristics of the resulting fuel gases have been considered. Introduction of an additional step of ...preliminary oxidative conversion (prereforming) of natural and associated petroleum gases makes it possible to oxidize selectively the “heavy” low-octane components of a complex hydrocarbon mixture and obtain fuel gas for power plants with a high methane number and a required lower heating value. Fuel characteristics of the gases obtained via partial oxidation can be further improved by admixture of gas-piston engine exhaust gas in an amount of about 100 m
3
/1000 m
3
to the air–fuel mixture. The version of controlling the fuel characteristics of complex gas mixtures, as described in the paper, is characterized by simplicity of engineering design, high feedstock flexibility, and the possibility to create simple-to-use modular automated systems for conditioning hydrocarbon gases in small gas fields or fields distant far from power plants.
Molecular surveys of eukaryotic microbial communities employing high-throughput sequencing (HTS) techniques are rapidly supplanting traditional morphological approaches due to their larger data ...output and reduced bench work time. Here, we directly compare morphological and Illumina data obtained from the same samples, in an effort to characterize ciliate faunas from sediments in freshwater environments. We show how in silico processing affects the final outcome of our HTS analysis, providing evidence that quality filtering protocols strongly impact the number of predicted taxa, but not downstream conclusions such as biogeography patterns. We determine the abundance distribution of ciliates, showing that a small fraction of abundant taxa dominates read counts. At the same time, we advance reasons to believe that biases affecting HTS abundances may be significant enough to blur part of the underlying biological picture. We confirmed that the HTS approach detects many more taxa than morphological inspections, and highlight how the difference varies among taxonomic groups. Finally, we hypothesize that the two datasets actually correspond to different conceptions of “diversity,” and consequently that neither is entirely superior to the other when investigating environmental protists.
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•Combination of micro-CT and nano-CT used to study methane-hydrate formation in coal.•Hydrates grow differently in coal (thin shells) and sand (shells, pore and water ...volumes).•Observed water extraction from coal particles along channels during competitive sorption.•Micro-porosity channels in coal particles are confirmed by nano-CT.•Water movement in thin pores at speed 3–4 mm/s observed from synchrotron micro-CT.
Fast 3D X-ray imaging has proved to provide crucial insights into multi-phase dynamic processes in various geo-materials. In particular, many in situ imaging experiments have been made to study gas-hydrate formation in porous sandy samples. Such imaging is challenging for the methane gas-hydrate formation in coal samples because of the coal micro-porosity structure and lower X-ray contrast. Here we present results of the first dynamic in situ micro-computed tomography experiment of methane-hydrate formation in coal samples. Synchrotron phase-contrast tomography techniques allowed to achieve necessary contrast levels to separate all the materials of interest (gas, water, coal, and gas hydrate) in reconstructed images with high spatial and temporal resolution. The imaging results are compared to the ones from a similar tomographic experiment with sand samples. Methane-hydrate formation is accompanied by the water movements caused by cryogenic water suction that happens in sequences of short fast movements with longer equilibrium states in between. Only one type of the hydrate formation was observed in coal (growth as shells on grain boundaries) as opposed to three types in sand (shells, growth into gas pockets, and inside water volumes). In particular, this leads to a slower hydrate-formation speed in coal. For the coal sample, we also observed water extraction from grains, and interpreted it as competitive sorption of methane. We visualized the dynamic behavior of this water extraction via micro-channels inside the coal grains, and performed nano-tomography imaging of these channels for a better understanding of this phenomenon.
Symbioses between bacteria and eukaryotes are widespread and may have significant impact on the evolutionary history of symbiotic partners. The order Rickettsiales is a lineage of intracellular ...Alphaproteobacteria characterized by an obligate association with a wide range of eukaryotic hosts, including several unicellular organisms, such as ciliates and amoebas. In this work, we characterized the Rickettsiales symbionts associated with two different genotypes of the freshwater ciliate Paramecium caudatum originated from freshwater environments in distant geographical areas. Phylogenetic analyses based on 16S rRNA gene showed that the two symbionts are closely related to each other (99.4% identity), belong to the family Rickettsiaceae, but are far-related with respect to previously characterized Rickettsiales. Consequently, they were assigned to a new species of a novel genus, namely “Candidatus Spectririckettsia obscura.” Screening on a database of short reads from 16S rRNA gene ampliconbased profiling studies confirmed that bacterial sequences related to the new symbiont are preferentially retrieved from freshwater environments, apparently with extremely scarce occurrence (< 0.1% positive samples). The present work provides new information on the still under-explored biodiversity of Rickettsiales, in particular those associated to ciliate host cells.
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