Hydrate Phase Equilibria and Structure Identification of the CH4 + CO2 + Thermodynamic Hydrate Promoter Systems for Application to CO2 Capture from Natural Gas

Some natural gas fields located in Southeast Asia contain high levels of CO2 content which can reduce energy density and increase production cost. Gas hydrate-based separation can be a good candidate for capturing CO2 from natural gas because the gas is obtained from high pressure reserviors. In this study, thermodynamic and structural analyses of the CH4 + CO2 hydrate were conducted in the presence of various thermodynamic hydrate promoters (THPs) such as tetrahydrofuran (THF), neohexane (NH), and tetra-n-butyl ammonium chloride (TBAC) in order to investigate CO2 capture characteristics depending on the structure. Three-phase (H-LW-V) or four-phase (H-LW-LNH-V) equilibria of the CH4 (50%) + CO2 (50%) + THP hydrates were measured to determine hydrate stability conditions. The phase equilibrium results showed that the addition of TBAC to the system resulted in the most significant thermodynamic promotion. Powder X-ray diffraction (PXRD) and Raman spectroscopy revealed that for the CH4 (50%) + CO2 (50%) gas mixture the addition of TBAC, THF, and NH induced the formation of semiclathrate, sII, and sH hydrate, respectively

Enclathration of CO2 as a Co-guest in sH Hydrates Formed from the CO2 + N2 + Methylcyclopentane Mixtures

Among the well-known three types of gas hydrates, structure H (sH) hydrates have several noteworthy features compared to structure I (sI) and structure II (sII) hydrates. sH hydrates can capture large-sized liquid hydrocarbon guests in the presence of help gases such as CH4 and N2. sH hydrates have a higher gas storage potential in their smaller cages compared to sI and sII hydrates, but the function of CO2 as a co-guest molecule in sH hydrate has been still controversial. In order to investigate the enclathration of CO2 as a co-guest in sH hydrates, the four-phase equilibria of the CO2 + N2 + methylcyclopentane (MCP) + water mixtures were measured and compared with three-phase equilibria of the corresponding CO2 + N2 + water mixtures. Furthermore, the structural transition according to the compositions of the gas mixtures (10, 20, 40, 60, and 80% CO2) was verified using Raman spectroscopy and powder X-ray diffraction (PXRD). At lower CO2 concentrations, CO2 was found to function as a co-guest of sH hydrates and due to the enclathration of MCP, four-phase equilibria showed a slight thermodynamic promotion. The structural transition from sH to sI was observed at CO2 concentrations higher than 20%

Contrasting life histories contribute to divergent patterns of genetic diversity and population connectivity in freshwater sculpin fishes

Abstract Background Life history characteristics are considered important factors influencing the evolutionary processes of natural populations, including the patterns of population genetic structure of a species. The sister species Cottus hangiongensis and C. koreanus are small bottom-dwelling freshwater sculpin fishes from South Korea that display marked life history divergence but are morphologically nearly indistinguishable. Cottus hangiongensis evolved an ‘amphidromous’ life history with a post-hatching pelagic larval phase. They spawn many small eggs in the low reaches of rivers, and hatched larvae migrate to the sea before returning to grow to maturity in the river mouth. In contrast, C. koreanus evolved a ‘fluvial’ landlocked type with benthic larvae. They release a smaller number of larger eggs, and the larvae undergo direct development, remaining benthic in the upstream rivers throughout their entire lives. We tested whether there were differences in patterns and levels of within-population genetic diversities and spatial population structure between the two closely related Korean sculpins using mitochondrial DNA control region sequences and seven nuclear microsatellite loci. Results The combined analyses of both marker sets revealed that C. hangiongensis harboured considerably higher levels of within-population genetic diversities (e.g. haplotype/allelic richness, heterozygosities) than C. koreanus. In contrast, the fluvial sculpin exhibited noticeably more spatial population structure than did the amphidromous sculpin, as suggested by pairwise F ST statistics. The finding that C. hangiongensis individuals comprised a single random mating population across the east-flowing river basins in the Korean Peninsula, whereas C. koreanus individuals comprised genetically discrete individual populations, was further supported by an individual-based Bayesian population assignment and also factorial correspondence analyses. Conclusions The higher genetic diversity, but lower population structure, of the amphidromous sculpin relative to the fluvial sculpin may have resulted from its greater larval dispersal and also possibly, higher fecundity accompanied by an amphidromous life history. Hence, we conclude that contrasting early life histories – including the presence or absence of the pelagic larval phase – may have led to divergent patterns of within-population genetic diversities and spatial population structure between the sister Cottus species following speciation from a common ancestor of marine sculpin

Application of the international league against rheumatism classification criteria for systemic juvenile idiopathic arthritis as a prognostic factor in patients with adults-onset Still’s disease

Abstract Background Adult-onset Still’s disease (AOSD) is an adult form of systemic juvenile idiopathic arthritis (JIA) that differs from the latter in its classification. This study evaluated the concordance between the International League Against Rheumatism (ILAR) criteria for systemic JIA and the Yamaguchi criteria and then compared their possible prognostic value in patients with AOSD. Methods In a retrospective review of 169 adults with suspected AOSD, patients were classified according to the Yamaguchi or ILAR criteria. Then the concordance in cross-referencing the other group with the different criteria was investigated and the sensitivity and specificity of each set of criteria were determined. Disease activity markers in AOSD patients were correlated with positivity according to both systems. Results Concordance was good in patients with suspected AOSD (k = 0.7144, p <  0.001) and low in those with a diagnosis of AOSD (k = 0.3787, p <  0.001). The sensitivity of the ILAR criteria in AOSD patients was 0.8864 (95% confidence interval (CI): 0.8322–0.9405), and the specificity was 0.7838 (0.6511, 0.9164). Positivity according to the ILAR criteria correlated with the systemic score (r = 0.763, p <  0.0001) and C-reactive protein levels (r = 0.183, p = 0.0356) and was associated with a relapse (odds ratio: 1.589, 95% CI: 1.043–2.421), macrophage activation syndrome (MAS; odds ratio: 1.993, 95% CI: 1.218–3.263) and care in the intensive care unit (ICU; odds ratio: 2.087, 95% CI: 1.086–4.011). Conclusions In AOSD patients, there is fair concordance between the Yamaguchi and ILAR criteria for systemic JIA. Positive ILAR criteria may be useful for identifying AOSD patients at high risk for relapse, MAS and the need for ICU care. Further studies including larger populations from several centers are needed to confirm our results regarding the utility of the ILAR criteria in AOSD patients

Additional file 1: of Contrasting life histories contribute to divergent patterns of genetic diversity and population connectivity in freshwater sculpin fishes

Table S1. Information of sampling localities, population codes, coordinate (latitude/longitude), and river basins. Table S2. Statistical tests for a recent bottleneck in each of the five and 10 populations of C. hangiongensis and C. koreanus, respectively from South Korea. P-values are based on the Wilcoxon test. Allelic frequency distribution shape was normal or shifted for mode-shift distortion. Population abbreviations as in text and Additional file 1: Table S1. (ZIP 26 kb

Species composition, diversity, and distribution of the genus Ulva along the coast of Jeju Island, Korea based on molecular phylogenetic analysis.

Species diversity in the genus Ulva remains understudied worldwide. Using molecular analyses we investigated the species composition, diversity, distribution, and relative frequencies of the genus Ulva along the entire coast of Jeju Island, off the southern tip of Korea. Species identification was performed for 215 samples collected from 23 sites, based on comprehensive phylogenetic and model-based species delimitation analyses using the sequences of two molecular markers, chloroplast elongation factor Tu (tufA) and nuclear rDNA internal transcribed spacer (ITS). We identified 193 specimens as nine Ulva species, 14 specimens as Blidingia spp., and eight samples undetermined, based on the combined analysis of tufA and ITS phylogenies. Two model-based approaches generally supported nine groups of Ulva species. Previously documented species complex, such as U. ohnoi-U. spinulosa and U. procera-U. linza showed discordant relationships between the two phylogenies. The occurrence of U. torta on Jeju Island was first observed, despite its existence on the mainland previously reported. Ulva australis [16 of 23 sites; 34.4% (relative frequency)], U. ohnoi (16; 21.9%), and U. procera (11; 14%) were found to be the predominant species. Our study highlights that molecular analysis is critical for species delimitation in the genus Ulva and provides fundamental information for an understanding of green-tide assemblages on the "biological hotspot" coastal ecosystem, Jeju Island in Korea. This study will also help to monitor and manage local green tides at the areas that are currently encountering rapid climate changes

Effect of fluorescent whitening agent on the transcription of cell damage-related genes in zebrafish embryos

7-Diethylamino-4-methylcoumarin (DEMC) is a fluorescent whitening agent (FWAs). There have been some studies on DEMC&apos;s protective effects against biological activity but there are few papers about the in vivo toxicity of DEMC. In this study, we used wild-type zebrafish embryos 3?days post fertilization (dpf). Test solutions with DEMC concentrations were negative control (without vehicle), 0 (with vehicle, 0.01% v/v ethanol), 0.25, 0.5, 0.75, 1.0, 1.25, 1.5 and 2?ppm. Embryos and larvae were counted for survival rate and hatching rate. Heart rates were also counted at 2.5 and 3.0?dpf. At 3.0?dpf, quantitative RT-PCR was performed with some samples (0, 0.25, 0.75 and 1.25?ppm) to determine the toxic effect to DEMC by detecting the expression levels of toxic-responsive genes. We used 11 genes, which included oxidative stress-related genes [sod(Mn), sod(Cu,Zn) and hsp70], mitochondrial metabolism-related genes (coxI, pyc, cyt and cyclinG1) and apoptosis-related genes (c-jun, bcl2, bax and p53). High-concentration DEMC-treated groups showed significant different survival rate, hatching rate and heart rate compared with low-concentration DEMC-treated groups. The LC50 of this chemical, 0.959?ppm, was calculated. We also confirmed that some genes in the DEMC exposure groups showed significantly up-regulations in expression levels compared with control groups. We concluded that the fluorescence agent, DEMC, has possible developmental toxicities and alteration effect of gene expression, which are related to oxidative stress, mitochondrial metabolism and apoptosis in zebrafish embryos. Copyright (c) 2011 John Wiley &amp; Sons, Ltd.N