Natural gas hydrate has been a critical risk to the safety of offshore oil and gas well test and subsea transportation. Herein, the effect of three quaternary ammonium salt (QAS) surfactants with monoethylene glycol (MEG) to methane hydrate agglomeration in water-oil system was experimentally studied by a rocking cell. Based on the hydrate volume fraction and the slider trajectory, a classification method of the gas hydrate anti-agglomerants was established. All the QASs in this work show the capability of reducing hydrate agglomeration, among which N¹,N³-didodecyl-N¹,N¹,N³,N³-tetramethylpropane-1,3-diaminium chloride (AA-2) has the best anti-agglomerating performance, and the slider moved at a large trajectory of 61-174 mm. The three QASs were compounded with 5, 10, and 15 wt% (based on water) MEG, respectively. Experimental results showed that AA-2 compounded with MEG (10 wt%) can effectively prevent hydrate agglomeration. The slider moved in the cell at the full trajectory range, showing the compound of grade A performance. The compound of QAS and MEG shows a synergistic effect. The addition of QAS can significantly reduce the required MEG dosage for the hydrate blockage prevention than the MEG only situation. Considering the economic factors of the filed hydrate management, the combination application of QAS + MEG may provide a promising option.

2015-01-01·Pharmacognosy magazine4区 · 医学

Region-selective biosynthesis of artemisinic acid glycosides by crown galls of Panax quinquefolium and their in vitro antitumor activities

4区 · 医学

Article

作者: Song, Liyan ; Chen, Lijia ; Yu, Rongmin ; Zhu, Jianhua ; Hu, Xianjing ; Wang, Mingxuan

BACKGROUND:

The biosynthesis of artemisinin derivatives is one of the interesting subjects. Artemisinic acid (AA) has been widely studied as a supposed intermediate in the biosynthetic pathway leading to artemisinin in Artemisia annua.

OBJECTIVE:

To investigate the bioconversion of AA by transgenic crown galls of Panax quinquefolium.

MATERIALS AND METHODS:

AA was administered into crown galls of P. quinquefolium and co-cultured for 2 days. The methanol extract was separated by column chromatography, and the structures of two biosynthesis products were elucidated by physicochemical and spectroscopic methods. Co-culture time curves on conversion were also established. In addition, the effects of AA on the growth and ginsenosides production of crown galls of P. quinquefolium were investigated. Furthermore, the in vitro antitumor activities of AA and two glycosides against HepG2 cell line were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay.

RESULTS:

Glycosylation of AA by crown galls of P. quinquefolium was observed, and two region-selectively glycosylated products were obtained (AA-1, AA-2), involving one new compound (AA-2). Their structures were elucidated to be AA β-D-glucopyranosyl ester (AA-1) and AA β-D-glucopyranosyl-(2 → 1)-β-D-glucopyranosyl ester (AA-2). The maximum yield of AA-1 was 19.3% on the 1(st) co-culture day while that of AA-2 was 59.1% on the 2(nd) day. MTT assay showed that the activity of monosaccharide glycoside (AA-1) was better than that of disaccharide glycoside (AA-2).

CONCLUSION:

Two AA glycosides involved one new compound with potential antitumor activity were obtained by region-selective biosynthesis with crown galls of P. quinquefolium.

2006-09-01·Systematic and applied microbiology2区 · 生物学

Tepidimonas thermarum sp. nov., a new slightly thermophilic betaproteobacterium isolated from the Elisenquelle in Aachen and emended description of the genus Tepidimonas

2区 · 生物学

Article

作者: Igor Tiago ; Milton S. da Costa ; António Veríssimo ; Luciana Albuquerque

Several non-pigmented bacterial isolates, with an optimum growth temperature of about 50-55 degrees C, were recovered from the Elisenquelle at Aachen, Germany. Phylogenetic analysis of the 16S rRNA gene sequence of strains AA-1(T) and AA-2 indicated that these organisms represent a new species of the genus Tepidimonas. The major fatty acids of strains AA-1(T) and AA-2 are 16:0 and 16:1 omega7c. Ubiquinone 8 is the major respiratory quinone, the major polar lipids are phosphotidylethanolamine and phosphotidylglycerol. The new isolates are aerobic; thiosulfate is oxidized to sulfate in the presence of a metabolizable carbon source. The organism assimilated organic acids and amino acids, but did not assimilate carbohydrates or polyols. On the basis of the phylogenetic analyses, physiological and biochemical characteristics, we propose that strains AA-1(T) (=LMG 23094(T); =CIP 108777(T)) and AA-2 (=LMG 23095; =CIP 108778) represents a new species for which we recommend the name Tepidimonas thermarum.

100 项与 AA-002 相关的药物交易

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