[Raman spectroscopic investigation of hydrogen storage in nitrogen gas hydrates].

Recently, hydrogen storage using clathrate hydrate as a medium has become a hotspot of hydrogen storage research In the present paper, the laser Raman spectroscopy was used to study the hydrogen storage in nitrogen hydrate. The synthetic nitrogen hydrate was reacted with hydrogen gas under relatively mild conditions (e.g., 15 MPa, -18 degrees C). The Raman spectra of the reaction products show that the hydrogen molecules have enclathrated the cavities of the nitrogen hydrate, with multiple hydrogen cage occupancies in the clathrate cavities. The reaction time is an important factor affecting the hydrogen storage in nitrogen hydrate. The experimental results suggest that nitrogen hydrates are expected to be an effective media for hydrogen storage.

[In situ Raman spectroscopic observation of micro-processes of methane hydrate formation and dissociation].

Micro laser Raman spectroscopic technique was used for in situ observation of the micro-processes of methane hydrate formed and decomposed in a high pressure transparent capillary. The changes in clathrate structure of methane hydrate were investigated during these processes. The results show that, during hydrate formation, the Raman peak (2 917 cm(-1)) of methane gas gradually splits into two peaks (2 905 and 2 915 cm(-1)) representing large and small cages, respectively, suggesting that the dissolved methane molecules go into two different chemical environments. In the meantime, the hydrogen bonds interaction is strengthened because water is changing from liquid to solid state gradually. As a result, the O-H stretching vibrations of water shift to lower wavenumber. During the decomposition process of methane hydrates, the Raman peaks of the methane molecules both in the large and small cages gradually clear up, and finally turn into a single peak of methane gas. The experimental results show that laser Raman spectroscopy can accurately demonstrate some relevant information of hydrate crystal structure changes during the formation and dissociation processes of methane hydrate.

[Determination of hydration number of methane hydrates using micro-laser Raman spectroscopy].

Methane hydrates are clathrate compounds that are formed by methane molecules and water molecules under low temperature and high pressure conditions. It was found that methane hydrates exist widely in sea-shelf floor and permafrost, and are considered as a potential energy resource. In the crystal lattice of clathrate hydrate, the water molecules form both large cages (5(12)6(2)) and small cages (5(12)) under the interaction of the hydrogen-hydrogen bond. In this paper, the authors designed a set of experimental apparatus for methane hydrates formation. Based on this equipment, the authors synthesized a series of methane hydrates in various systems in laboratory, including SDS solution (3% Wt) and methane, powdered ice and methane, and powdered ice and methane and natural sand with various sizes (i. e. 250-350, 180-250, 125-180 and 63-90 microm), under different temperature and pressure. The authors also designed a small device which was proved to be convenient for Raman determination of the methane hydrates. Raman spectroscopy was used to analyze the methane hydrates and to measure the structural parameters such as hydration numbers and cage occupancies. The results show that the methane hydrate samples are all in structure I type, and hydration numbers and cage occupancies are almost independent of the sediment sizes. In the three systems, the large cages of methane hydrate samples are nearly full occupied, with the occupancy ratios larger than 97%, whereas the small cages between 80% and 86%. The hydration numbers of these methane hydrate samples are between 6.05 and 6.15.

Marinobacter segnicrescens sp. nov., a moderate halophile isolated from benthic sediment of the South China Sea.

A Gram-negative, motile, non-spore-forming and moderately halophilic ellipsoid-shaped marine coccobacillus, designated strain SS011B1-4(T), was isolated from benthic sediment of the South China Sea. Optimum growth occurred at 30-37 degrees C, pH 7.5-8.0 and 4-8 % (w/v) NaCl. Strain SS011B1-4(T) utilized a variety of organic substrates as sole carbon sources, but did not utilize toluene, n-tetradecane or crude oil. Strain SS011B1-4(T) had ubiquinone-9 as the major respiratory quinone and C(18 : 1)omega9c, C(16 : 0) and C(12 : 0) 3-OH as the predominant fatty acids. The genomic DNA G+C content was 62.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SS011B1-4(T) belonged to the genus Marinobacter of the Gammaproteobacteria. The results of the phenotypic, phylogenetic and genomic analyses revealed that strain SS011B1-4(T) represents a novel species of the genus Marinobacter. The name Marinobacter segnicrescens sp. nov. is therefore proposed, with strain SS011B1-4(T) (=LMG 23928(T)=CGMCC 1.6489(T)) as the type strain.

Oceanicola nanhaiensis sp. nov., isolated from sediments of the South China Sea.

A Gram-negative, non-motile, rod-shaped bacterium, strain SS011B1-20(T), was isolated from sediments of the South China Sea. Growth occurred at NaCl concentrations between 0 and 10 % and at temperatures between 10 and 37 degrees C. Strain SS011B1-20(T) contained Q-10 as the major respiratory quinone and C(18 : 1)omega7c (81.2 %), C(16 : 0) (7.0 %) and C(18 : 1) methyl (4.3 %) as the predominant fatty acids. The G+C content of the genomic DNA was 64.7 mol%. A phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain SS011B1-20(T) belonged to a clade within the genus Oceanicola in the Alphaproteobacteria, the highest sequence similarities being found with respect to Oceanicola batsensis (96.3 %) and with Oceanicola granulosus (94.9 %). Strain SS011B1-20(T) could be clearly distinguished from other Oceanicola species on the basis of the genotypic, phenotypic and phylogenetic data. Thus, it is proposed that strain SS011B1-20(T) represents a novel species of the genus Oceanicola, with the name Oceanicola nanhaiensis sp. nov. The type strain is SS011B1-20(T) (=LMG 23508(T)=CGMCC 1.6293(T)).