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  • 1
    Publication Date: 2016-02-02
    Description: Reaction of ZrC with Pd at temperatures up to 1500°C was examined using ZrC/Pd composite, Pd/ZrC-coated TRISO particles, and Pd/ZrC bulk diffusion couples experiments. Intermetallic phase (Pd 3 Zr) and amorphous carbon at the ZrC–Pd interfaces were identified by X-ray diffraction (XRD), Raman and scanning electron microscope (SEM). Moreover, thicknesses of Pd 3 Zr layers were measured by energy-dispersive X-ray spectrometry (EDS). The validity of the reaction was proved by thermodynamic calculation. The reaction kinetics parameters, i.e., the activation energy (208.2–266.5 kJ/mol) and the reaction order (3.38–3.78) for Pd attacking through a ZrC coating in TRISO particles were determined based on both the DSC curves and the growth of the Pd 3 Zr layer.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
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  • 2
    Publication Date: 2012-09-08
    Description: ABSTRACT Small patterned-ground features (PGFs) in the Arctic have unique soil properties that vary with latitude and may greatly affect tundra biogeochemistry. Because nitrogen availability can strongly limit arctic vegetation growth, we examined how soil nitrogen transformations differ between PGFs and the surrounding inter-PGF tundra along an arctic latitudinal gradient. We collected soils at eight sites from the Alaskan Low Arctic to the Canadian High Arctic. The soils were incubated for 21 days at 9 °C and 15 °C and analysed for changes in total inorganic nitrogen, nitrate and extractable organic nitrogen (EON). We found greater nitrogen immobilisation in the surrounding inter-PGF soils than in the PGF soils. Along the latitudinal gradient, differences in net nitrogen mineralisation and EON cycling between PGF and inter-PGF soils were strongly influenced by the presence of a pH boundary within the Low Arctic and the transition between the High and Low Arctic, with greater immobilisation in the nonacidic and Low Arctic sites, respectively. Incubation temperature affected EON flux but did not affect net nitrogen mineralisation or nitrification. These results show that spatial heterogeneity at several scales can influence soil nitrogen dynamics, and is therefore an important influence on arctic ecosystem function. Copyright © 2012 John Wiley & Sons, Ltd.
    Print ISSN: 1045-6740
    Electronic ISSN: 1099-1530
    Topics: Geography , Geosciences
    Published by Wiley
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  • 3
    Publication Date: 2012-07-12
    Description: Two new clerodane-type diterpenes, solidagocanins A and B ( 1 and 2 , resp.), as well as two known compounds, mellein ( 3 ) and physcion ( 4 ), were isolated from the aerial parts of Solidago canadensis. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D-NMR techniques.
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 4
    Publication Date: 2011-04-12
    Description: Sampsone A ( 1 ), a novel prenylated aromatic lactone, and sampsone B ( 2 ), an unusual dihydrodibenzodioxinone, together with sampsone C ( 3 ), a new xanthone, were isolated from the aerial parts of Hypericum sampsonii. Their structures were determined by spectroscopic methods which were mainly 1D- and 2D-NMR techniques, and the structure of sampsone B ( 2 ) was also confirmed by X-ray crystallographic analysis. All of these compounds were evaluated for in vitro antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Only sampsone A showed moderate antibacterial activities at a minimum inhibitory concentration ( MIC ) of 32 μg/ml.
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
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  • 5
    Publication Date: 2011-04-20
    Description: Carbon, nitrogen, and material fluxes were quantified at 48 sampling locations along the 1957 km coastline of the Beaufort Sea, Alaska. Landform characteristics, soil stratigraphy, cryogenic features, and ice contents were determined for each site. Erosion rates for the sites were quantified using satellite images and aerial photos, and the rates averaged across the coastline increased from 0.6 m yr−1 during circa 1950–1980 to 1.2 m yr−1 during circa 1980–2000. Soils were highly cryoturbated, and organic carbon (OC) stores ranged from 13 to 162 kg OC m−2 in banks above sea level and averaged 63 kg OC m−2 over the entire coastline. Long-term (1950–2000) annual lateral fluxes due to erosion were estimated at −153 Gg OC, −7762 Mg total nitrogen, −2106 Tg solids, and −2762 Tg water. Total land area loss along the Alaska Beaufort Sea coastline was estimated at 203 ha yr−1. We found coastal erosion rates, bank heights, soil properties, and material stores and fluxes to be extremely variable among sampling sites. In comparing two classification systems used to classifying coastline types from an oceanographic, coastal morphology perspective and geomorphic units from a terrestrial, soils perspective, we found both systems were effective at differentiating significant differences among classes for most material stores, but the coastline classification did not find significant differences in erosion rates because it lacked differentiation of soil texture.
    Print ISSN: 0148-0227
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2014-10-31
    Description: Objective To obtain microRNA (miRNA) profile and clarify their biological function in tumorigenic Sca-1 + CD34 + cells during carcinogenesis of lung adenocarcinoma. Methods After intranasal infection with recombinant Adeno-Cre viruses (AdV-Cre), lung adenocarcinoma was identified pathologically in Lox-stop-lox Kras (LSL-Kras) G12D mice. Sca-1 + CD34 + cells were sorted by flow cytometry and tested for tumor-initiating ability, self-renewal and tumorigenicity. MiRNA profiles were obtained using microarray and further confirmed by real-time RT-PCR (qRT-PCR). MiRNA functions were predicted bioinformatically, and miR-294 function was verified to explore its role in tumor migration and invasion. Results Lung adenocarcinoma was induced in LSL-Kras G12D mice within 30 days. In vivo, the tumorigenicity of Sca-1 + CD34 + cells was 25 times stronger than Sca-1 - CD34 - cells. During tumorigenesis of lung adenocarcinoma, the expression of 145 miRNAs in Sca-1 + CD34 + cells increased and 72 miRNAs decreased ( P  〈 0.01). Four successively up-regulated miRNAs (miR-15a*, miR-203, miR-294 and miR-295*) and three successively down-regulated ones (miR-19b, miR-483 and miR-615–5p) were identified. Among them, miR-294 could constitutively bind to 3'-UTR of matrix metalloproteinase 3 (MMP3), and down-regulate MMP3 protein expression. MiR-294 also significantly inhibited migration and invasion of Lewis lung cancer cells. Conclusion MiRNAs are characteristically expressed in tumor-initiating Sca-1 + CD34 + cells of lung adenocarcinoma, and may play important roles during the carcinogenesis of lung adenocarcinoma. J. Cell. Biochem. © 2014 Wiley Periodicals, Inc.
    Electronic ISSN: 0091-7419
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Wiley
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  • 7
    Publication Date: 2013-05-18
    Description: Two new bis-alkaloids, flavifloramides A ( 1 ) and B ( 2 ), as well as two known alkaloids, N - trans -feruloyltyramine ( 3 ) and paprazine ( 4 ), were isolated from the aerial part of Piper flaviflorum. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D-NMR techniques.
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 8
    Publication Date: 2017-06-02
    Description: Northern circumpolar permafrost soils contain more than a third of the global Soil Organic Carbon pool (SOC). The sensitivity of this carbon pool to a changing climate is a primary source of uncertainty in simulation-based climate projections. These projections, however, do not account for the accumulation of soil deposits at the base of hillslopes (hill-toes), and the influence of this accumulation on the distribution, sequestration, and decomposition of SOC in landscapes affected by permafrost. Here we combine topographic models with soil-profile data and topographic analysis to evaluate the quantity and uncertainty of SOC mass stored in perennially frozen hill-toe soil deposits. We show that in Alaska this SOC mass introduces an uncertainty that is 〉200 % than state-wide estimates of SOC stocks (77 PgC), and that a similarly large uncertainty may also pertain at a circumpolar scale. Soil sampling and geophysical-imaging efforts that target hill-toe deposits can help constrain this large uncertainty.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
    Publication Date: 2017-11-14
    Description: The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well-constrained. Here, we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14 C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bedload of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrially-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on Beaufort Shelf.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 10
    Publication Date: 2014-05-15
    Description: Two new iridoids, jatamanvaltrates P and Q ( 1 and 2 , resp.), together with three known iridoids, rupesin B ( 3 ), chlorovaltrate ( 4 ), and valtrate ( 5 ), were isolated from the root and rhizome of Valeriana jatamansi Jones . The structures of the new compounds were elucidated by spectroscopic analyses, including 2D-NMR techniques.
    Print ISSN: 0018-019X
    Electronic ISSN: 1522-2675
    Topics: Chemistry and Pharmacology
    Published by Wiley
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