The Experts below are selected from a list of 14724 Experts worldwide ranked by ideXlab platform
Woeilih Jeng - One of the best experts on this subject based on the ideXlab platform.
-
a comparison of sedimentary Aliphatic Hydrocarbon distribution between east china sea and southern okinawa trough
Continental Shelf Research, 2008Co-Authors: Woeilih Jeng, Chihan HuhAbstract:Abstract In this study, 34 surface sediments were collected from the East China Sea (ECS) shelf, and their Aliphatic Hydrocarbon concentrations measured. The Hydrocarbon distribution of the ECS was compared with that of the southern Okinawa Trough (SOT) to explore for possible relations between the two coastal marine areas. Results from principal component analysis performed on Hydrocarbon data of ECS and SOT sediments indicated that the first two components explained 74% of the total variance and that the score plot of the two components showed three groups. The first group defined by the 12 SOT sediments contained three sediments on the ECS inner shelf. Eight sediments except one on the ECS inner shelf formed group II, and the remaining 21 sediments located away from the inner shelf (mainly on the mid-to-outer shelf) formed group III. Even though three inner shelf sediments cluster with group I, the separation between groups I and II suggests that the Hydrocarbon relation between the inner shelf and the SOT is very weak. Groups II and III do not cluster together; their separation is supported by previous studies showing that Changjiang River sediment tends to remain in the coastal waters and is transported to the south by the coastal currents along the Chinese coast. Also, group I does not cluster with group III, signifying a great difference between them; this can be attributed to little material exchange between the ECS and the SOT because of the Kuroshio Current. In addition, the SOT and ECS inner shelf had carbon preference index values averaging 2.92±0.79 ( n =12) and 4.56±0.93 ( n =8), terrestrial/aquatic ratios averaging 9.64±4.33 ( n =12) and 50.4±58.0 ( n =8), and ( n C 27 + n C 29 + n C 31 )/TOC ratios averaging 1731±482×10 −7 g(g C) −1 ( n =12) and 3016±868×10 −7 g(g C) −1 ( n =8), respectively; strongly indicating considerable differences between the two areas. Based on the present results, Hydrocarbon export from the ECS inner shelf to the SOT appears to be unlikely.
-
Aliphatic Hydrocarbon concentrations in short sediment cores from the southern okinawa trough implications for lipid deposition in a complex environment
Continental Shelf Research, 2007Co-Authors: Woeilih JengAbstract:Abstract Seven short sediment cores from the southern Okinawa Trough were collected and analyzed for the Aliphatic Hydrocarbon concentrations by capillary gas chromatography to explore the deposition of Hydrocarbons to this area. For all cores studied, ratios of ΣHydrocarbons/TOC, (nC27+nC29+nC31)/TOC, terrigenous/aquatic, and diploptene/ΣC25–33 n-alkanes fluctuated around a mean value with coefficients of variation ranging from 9.0% to 19.7%, 4.9% to 20.0%, 27.3% to 129%, and 3.8% to 163%, respectively. For the nC31/(nC27+nC29+nC31) ratio, only station 21 showed fluctuation. Moreover, the carbon preference indexes in the C25–C33 n-alkane range also exhibited fluctuating values with coefficients of variation of 1.9–14.4%. These results indicate that concentrations of Hydrocarbon inputs to the sampling sites vary with time; this may result from complex current flow and sediment transport, leading to variable lipid deposition. In addition, significant correlation between diploptene (hop-22(29)-ene) and higher plant n-alkanes was found for cores 21, 42 and 46, indicating that diploptene was predominantly from higher plant sources. However, no correlation between diploptene and higher plant n-alkanes was found for cores 20, 36, 43 and 44; autochthonous sources of diploptene in these cores were quite probable.
-
a comparison of sedimentary Aliphatic Hydrocarbon distribution between the southern okinawa trough and a nearby river with high sediment discharge
Estuarine Coastal and Shelf Science, 2006Co-Authors: Woeilih Jeng, Chihan HuhAbstract:Twelve surface sediments from the southern Okinawa Trough (OT) and nine surface sediments from a nearby river, the Lanyang River (LR), with high sediment discharge were analyzed for comparison of their Aliphatic Hydrocarbon distributions. Performing cluster analysis on all Hydrocarbon data of LR and OT sediments showed that the two areas had a similarity level of only 0.15, meaning that they were quite dissimilar. The average ratio of terrigenous to aquatic n-alkanes was 0.99 for LR sediments and 9.64 for OT sediments, indicating that the concentrations of n-alkanes in LR and OT sediments were quite different. Furthermore, the mean pristane/phytane ratios for LR and OT sediments were 1.01 and 2.57, respectively; the difference between them was significant (Student’s t test, at the 99% significance level). The carbon preference index (CPI) of C25eC33 n-alkanes averaged 3.26 (range 2.16e4.59) for LR sediments and 2.92 (range 2.35e5.24) for OT sediments; no significant difference was found between the two CPI averages (Student’s t test, at the 99% confidence level). However, higher plant n-alkanes generally maximized at C29 for LR sediments, but maximized at C31 for all OT sediments, strongly indicating significant differences in the origins of the Hydrocarbons in these two areas. All present results appear to suggest that LR sediments are not a major Hydrocarbon source for OT sediments. In addition, there was no positive, linear correlation between diploptene (hop-22(29)-ene) and terrestrial higher plant n-alkanes for LR and OT sediments.
Chihan Huh - One of the best experts on this subject based on the ideXlab platform.
-
a comparison of sedimentary Aliphatic Hydrocarbon distribution between east china sea and southern okinawa trough
Continental Shelf Research, 2008Co-Authors: Woeilih Jeng, Chihan HuhAbstract:Abstract In this study, 34 surface sediments were collected from the East China Sea (ECS) shelf, and their Aliphatic Hydrocarbon concentrations measured. The Hydrocarbon distribution of the ECS was compared with that of the southern Okinawa Trough (SOT) to explore for possible relations between the two coastal marine areas. Results from principal component analysis performed on Hydrocarbon data of ECS and SOT sediments indicated that the first two components explained 74% of the total variance and that the score plot of the two components showed three groups. The first group defined by the 12 SOT sediments contained three sediments on the ECS inner shelf. Eight sediments except one on the ECS inner shelf formed group II, and the remaining 21 sediments located away from the inner shelf (mainly on the mid-to-outer shelf) formed group III. Even though three inner shelf sediments cluster with group I, the separation between groups I and II suggests that the Hydrocarbon relation between the inner shelf and the SOT is very weak. Groups II and III do not cluster together; their separation is supported by previous studies showing that Changjiang River sediment tends to remain in the coastal waters and is transported to the south by the coastal currents along the Chinese coast. Also, group I does not cluster with group III, signifying a great difference between them; this can be attributed to little material exchange between the ECS and the SOT because of the Kuroshio Current. In addition, the SOT and ECS inner shelf had carbon preference index values averaging 2.92±0.79 ( n =12) and 4.56±0.93 ( n =8), terrestrial/aquatic ratios averaging 9.64±4.33 ( n =12) and 50.4±58.0 ( n =8), and ( n C 27 + n C 29 + n C 31 )/TOC ratios averaging 1731±482×10 −7 g(g C) −1 ( n =12) and 3016±868×10 −7 g(g C) −1 ( n =8), respectively; strongly indicating considerable differences between the two areas. Based on the present results, Hydrocarbon export from the ECS inner shelf to the SOT appears to be unlikely.
-
a comparison of sedimentary Aliphatic Hydrocarbon distribution between the southern okinawa trough and a nearby river with high sediment discharge
Estuarine Coastal and Shelf Science, 2006Co-Authors: Woeilih Jeng, Chihan HuhAbstract:Twelve surface sediments from the southern Okinawa Trough (OT) and nine surface sediments from a nearby river, the Lanyang River (LR), with high sediment discharge were analyzed for comparison of their Aliphatic Hydrocarbon distributions. Performing cluster analysis on all Hydrocarbon data of LR and OT sediments showed that the two areas had a similarity level of only 0.15, meaning that they were quite dissimilar. The average ratio of terrigenous to aquatic n-alkanes was 0.99 for LR sediments and 9.64 for OT sediments, indicating that the concentrations of n-alkanes in LR and OT sediments were quite different. Furthermore, the mean pristane/phytane ratios for LR and OT sediments were 1.01 and 2.57, respectively; the difference between them was significant (Student’s t test, at the 99% significance level). The carbon preference index (CPI) of C25eC33 n-alkanes averaged 3.26 (range 2.16e4.59) for LR sediments and 2.92 (range 2.35e5.24) for OT sediments; no significant difference was found between the two CPI averages (Student’s t test, at the 99% confidence level). However, higher plant n-alkanes generally maximized at C29 for LR sediments, but maximized at C31 for all OT sediments, strongly indicating significant differences in the origins of the Hydrocarbons in these two areas. All present results appear to suggest that LR sediments are not a major Hydrocarbon source for OT sediments. In addition, there was no positive, linear correlation between diploptene (hop-22(29)-ene) and terrestrial higher plant n-alkanes for LR and OT sediments.
Wolfram Thiemann - One of the best experts on this subject based on the ideXlab platform.
-
Gas chromatographic separation of saturated Aliphatic Hydrocarbon enantiomers on permethylated β‐cyclodextrin
Chirality, 2003Co-Authors: Uwe J. Meierhenrich, Mai‐julie Nguyen, Bernard Barbier, André Brack, Wolfram ThiemannAbstract:Enantiomers of chiral Aliphatic Hydrocarbons are generally difficult to separate because they lack functional groups to be derivatized in order to generate diastereomers. The systematic and quantitative separation of a series of branched Hydrocarbon enantiomers using a chiral cyclodextrin stationary phase and a cryostat-controlled gas chromatograph is described. The use of a cryogenic system allows the improvement of separations for various chiral Aliphatic Hydrocarbons. The molecular cyclodextrin-based mechanism of the achieved enantiomeric separations is discussed briefly. Possible applications of this analytical technique are summarized, with special emphasis on the planned enantiomeric separation experiment on a cometary nucleus.
-
Gas chromatographic separation of saturated Aliphatic Hydrocarbon enantiomers on permethylated beta-cyclodextrin.
Chirality, 2003Co-Authors: Uwe J. Meierhenrich, Bernard Barbier, André Brack, Mai-julie Nguyen, Wolfram ThiemannAbstract:Enantiomers of chiral Aliphatic Hydrocarbons are generally difficult to separate because they lack functional groups to be derivatized in order to generate diastereomers. The systematic and quantitative separation of a series of branched Hydrocarbon enantiomers using a chiral cyclodextrin stationary phase and a cryostat-controlled gas chromatograph is described. The use of a cryogenic system allows the improvement of separations for various chiral Aliphatic Hydrocarbons. The molecular cyclodextrin-based mechanism of the achieved enantiomeric separations is discussed briefly. Possible applications of this analytical technique are summarized, with special emphasis on the planned enantiomeric separation experiment on a cometary nucleus.
-
gas chromatographic separation of saturated Aliphatic Hydrocarbon enantiomers on permethylated β cyclodextrin
Chirality, 2003Co-Authors: Uwe J. Meierhenrich, Bernard Barbier, André Brack, Mai-julie Nguyen, Wolfram ThiemannAbstract:Enantiomers of chiral Aliphatic Hydrocarbons are generally difficult to separate because they lack functional groups to be derivatized in order to generate diastereomers. The systematic and quantitative separation of a series of branched Hydrocarbon enantiomers using a chiral cyclodextrin stationary phase and a cryostat-controlled gas chromatograph is described. The use of a cryogenic system allows the improvement of separations for various chiral Aliphatic Hydrocarbons. The molecular cyclodextrin-based mechanism of the achieved enantiomeric separations is discussed briefly. Possible applications of this analytical technique are summarized, with special emphasis on the planned enantiomeric separation experiment on a cometary nucleus.
Miwa Goto - One of the best experts on this subject based on the ideXlab platform.
-
spatially resolved 3 micron spectroscopy of iras 22272 5435 formation and evolution of Aliphatic Hydrocarbon dust in proto planetary nebulae
The Astrophysical Journal, 2003Co-Authors: Miwa Goto, Wolfgang Gaessler, Yutaka Hayano, Masanori Iye, Yukiko Kamata, Tomio Kanzawa, Naoto Kobayashi, Y MinowaAbstract:We present medium-resolution 3 lm spectroscopy of the carbon-rich proto–planetary nebula IRAS 22272+5435. Spectroscopy with the Subaru Telescope adaptive optics system revealed a spatial variation of Hydrocarbon molecules and dust surrounding the star. The rovibrational bands of acetylene (C2H2) and hydrogen cyanide (HCN) at 3.0 lm are evident in the central star spectra. The molecules are concentrated in the compact region near the center. The 3.3 and 3.4 lm emission of aromatic and Aliphatic Hydrocarbons is detected at 600–1300 AU from the central star. The separation of spatial distribution between gas and dust suggests that the small Hydrocarbon molecules are indeed the source of solid material and that the gas left over from the grain formation is being observed near the central star. The intensity of Aliphatic Hydrocarbon emission relative to the aromatic Hydrocarbon emission decreases with distance from the central star. The spectral variation is well matched to that of a laboratory analog thermally annealed with different temperatures. We suggest that either the thermal process after the formation of a grain or the variation in the temperature in the dust-forming region over time determines the chemical composition of the Hydrocarbon dust around the proto–planetary nebula. Subject headings: circumstellar matter — dust, extinction — infrared: ISM — ISM: evolution — stars: AGB and post-AGB — stars: individual (IRAS 22272+5435)
-
spatially resolved 3 um spectroscopy of iras 22272 5435 formation and evolution of Aliphatic Hydrocarbon dust in proto planetary nebula
arXiv: Astrophysics, 2003Co-Authors: Miwa Goto, Wolfgang Gaessler, Yutaka Hayano, Masanori Iye, Yukiko Kamata, Tomio Kanzawa, Naoto Kobayashi, Y Minowa, D SaintjacquesAbstract:We present medium-resolution 3 um spectroscopy of the carbon-rich proto-planetary nebula IRAS 22272+5435. Spectroscopy with the Subaru Telescope adaptive optics system revealed a spatial variation of Hydrocarbon molecules and dust surrounding the star. The ro-vibrational bands of acetylene (C2H2) and hydrogen cyanide (HCN) at 3.0 um are evident in the central star spectra. The molecules are concentrated in the compact region near the center. The 3.3 and 3.4 um emission of aromatic and Aliphatic Hydrocarbons is detected at 600--1300 AU from the central star. The separation of spatial distribution between gas and dust suggests that the small Hydrocarbon molecules are indeed the source of solid material, and that the gas leftover from the grain formation is being observed near the central star. The intensity of Aliphatic Hydrocarbon emission relative to the aromatic Hydrocarbon emission decreases with distance from the central star. The spectral variation is well matched to that of a laboratory analog thermally annealed with different temperatures. We suggest that either the thermal process after the formation of a grain or the variation in the temperature in the dust-forming region over time determines the chemical composition of the Hydrocarbon dust around the proto-planetary nebula.
Tianhu Chen - One of the best experts on this subject based on the ideXlab platform.
-
source apportionment of sediment associated Aliphatic Hydrocarbon in a eutrophicated shallow lake china
Environmental Science and Pollution Research, 2012Co-Authors: Jizhong Wang, Zeyu Yang, Tianhu ChenAbstract:Chaohu Lake, one of the most eutrophicated lakes in China, has been suffering from long-term outside pollution, urban sewage, river outflows, and agricultural runoff which expectedly have been the main contributors of Hydrocarbons. However, the contributions from these various sources have not been specified. The present study is aimed at identifying the potential sources of Hydrocarbons in surface sediment around the whole lake and assessing the relative contributions using principal components analysis–multiple linear regression (PCA-MLR). Sixty-one surface sediments covering the whole Chaohu Lake and three main estuaries of inflowing rivers were collected, dried, extracted, and analyzed for 27 normal alkanes (n-alkanes, from C12 to C38, defined Σ27AH) and unresolved complex mixture (UCM) by GC/MS. Diagnostic ratios and PCA-MLR were utilized to apportion their sources. The concentrations of Σ27AH and UCM ranged from 434 to 3,870 ng/g and 11.9 to 325 μg/g dry weight, respectively, for all samples. The concentrations of Σ27AH in western region and estuary of Nanfei River were slightly higher but without statistical significance than those from eastern region and estuaries of Yuxi River and Hangbu River. The concentration of UCM from western region was significantly higher than that obtained from eastern region. These results reflect the importance of input of urban runoff by Nanfei River and serious eutrophication in western region. Aliphatic Hydrocarbons in Chaohu Lake were mainly derived from high plant wax with mixed sources of phytoplankton and petroleum. Weak microbial decomposition of n-alkanes would be expected to occur from the low ratios of isoprenoid Hydrocarbons pristine (pri) and phytane (phy) to n-C17 and n-C18, respectively. Higher plant, fossil combustion, petroleum residue, and phytoplankton were proposed as the main origines of Aliphatic Hydrocarbons by PCA while the contributions of individual n-alkane homologues, pri and phy from the identified sources (31 % from higher plant, 30 % from fossil combustion, 26 % from petroleum, and 19 % from phytoplankton) were well predicted using MLR. The distribution profile and corresponding diagnostic ratios of normal alkanes show the promising potential as a useful proxy for estimating the source and loading of pollutants in Chaohu Lake.
