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  • Analytical Chemistry and Spectroscopy  (4)
  • *Ecosystem  (2)
  • 1
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    Increase in forest water-use efficiency as atmospheric carbon dioxide concentrations rise (2013)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2013-07-12
    Description: Terrestrial plants remove CO2 from the atmosphere through photosynthesis, a process that is accompanied by the loss of water vapour from leaves. The ratio of water loss to carbon gain, or water-use efficiency, is a key characteristic of ecosystem function that is central to the global cycles of water, energy and carbon. Here we analyse direct, long-term measurements of whole-ecosystem carbon and water exchange. We find a substantial increase in water-use efficiency in temperate and boreal forests of the Northern Hemisphere over the past two decades. We systematically assess various competing hypotheses to explain this trend, and find that the observed increase is most consistent with a strong CO2 fertilization effect. The results suggest a partial closure of stomata-small pores on the leaf surface that regulate gas exchange-to maintain a near-constant concentration of CO2 inside the leaf even under continually increasing atmospheric CO2 levels. The observed increase in forest water-use efficiency is larger than that predicted by existing theory and 13 terrestrial biosphere models. The increase is associated with trends of increasing ecosystem-level photosynthesis and net carbon uptake, and decreasing evapotranspiration. Our findings suggest a shift in the carbon- and water-based economics of terrestrial vegetation, which may require a reassessment of the role of stomatal control in regulating interactions between forests and climate change, and a re-evaluation of coupled vegetation-climate models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keenan, Trevor F -- Hollinger, David Y -- Bohrer, Gil -- Dragoni, Danilo -- Munger, J William -- Schmid, Hans Peter -- Richardson, Andrew D -- England -- Nature. 2013 Jul 18;499(7458):324-7. doi: 10.1038/nature12291. Epub 2013 Jul 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA. tkeenan@oeb.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23842499" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere/chemistry ; Carbon Dioxide/*analysis ; *Ecosystem ; Plant Leaves/chemistry ; Trees/*chemistry ; Water/*analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Keenan et al. reply (2014)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2014-03-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keenan, Trevor F -- Hollinger, David Y -- Bohrer, Gil -- Dragoni, Danilo -- Munger, J William -- Schmid, Hans Peter -- Richardson, Andrew D -- England -- Nature. 2014 Mar 13;507(7491):E2-3. doi: 10.1038/nature13114.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia. ; USDA Forest Service, Northern Research Station, Durham, New Hamphire 03824, USA. ; Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, Ohio 43210, USA. ; Department of Geography, Indiana University, Bloomington, Indiana 47405, USA. ; School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. ; Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen 82467, Germany. ; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24622207" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon Dioxide/*analysis ; *Ecosystem ; Trees/*chemistry ; Water/*analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
    Electronic Resource
    Electronic Resource
    Glass capillary GC/MS of butter triglycerides (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 675-676 
    Details
    ISSN: 0935-6304
    Keywords: Triglycerides ; GC/MS of triglycerides ; Capillary, glass ; All-glass GC/MS interface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240021109
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation and evaluation of OV-240-OH coated glass capillary columns for isomer specific determination of PCDDs and PCDFs (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 548-552 
    Details
    ISSN: 0935-6304
    Keywords: Glass capillary gas chromatography ; Immobilization ; OV-240-OH cyanopropylpolysiloxane ; Isomer specificity ; Polychlorinated dibenzo-p-dioxins ; Polychlorinated dibenzofurans ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillaries were leached, dehydrated, persilylated with 1, 3-bis (3-cyanopropyl) tetramethyldisiloxane, and coated with OV-240-OH. After crosslinking and binding the phase to the glass surface the columns showed high separation efficiency, high temperature stability, and inertness comparable to persilylated apolar columns. Column performance is shown to be superior to liquid phase cyanopropyl columns such as SP 2330. The excellent separation capabilities together with the selectivity of the phase makes OV-240-OH coated columns a valuable tool for the determination of toxic isomers in complex mixtures of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The order of elution of individual TCDD isomers was found to be similar to that described for SP 2330 or Silar 10c. The detection of PCDDs and PCDFs in a fly ash extract further illustrates the utility of OV-240-OH coated columns. The high temperature limit of these columns opens the way for the analysis of high boiling compounds such as mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240101004
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  • 5
    Electronic Resource
    Electronic Resource
    Chromatographic properties of various polysiloxane stationary phases for separation of 2,3,7,8-chloro-substituted dibenzo-p-dioxin and dibenzofuran isomers-a systematic comparison (1989)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 665-668 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Glass capillary columns ; OH-Terminated polysiloxane phases ; PS-347.5, OV-17-OH, OV-240-OH ; SP-2330 ; Polychlorinated dibenzo-p-dioxin ; Polychlorinated dibenzofuran ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillaries coated with four crosslinked and surface-bonded OH-terminated polysiloxanes [PS 347.5, OV-17-OH, OV-225-OH, and OV-240-OH] were compared with commonly used methyl-terminated SP-2330-coated columns with respect to their selectivity for the separation of 2,3,7,8-chloro-substituted dibenzo-p-dioxins and dibenzofurans. The methyl- and phenyl-substituted phases [PS 347.5 and OV-17-OH] exhibit only moderate isomer selectivity which limits their applicability in this field. The examined 3-cyanopropyl-substituted phases [OV-225-OH, OV-240-OH, and SP-2330] allow complete separation of all 2,3,7,8-chlorosubstituted PCDDs and PCDFs. With SP-2330 longer columns are required (50 m) for baseline separation of critical groups of isomers. OV-225-OH was found to be the most suitable phase as to isomer selectivity. In comparison to SP-2330, the analysis times can be reduced by a factor of two.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240121007
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  • 6
    Electronic Resource
    Electronic Resource
    A versatile all-glass GC/MS interface for capillary columns (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 225-228 
    Details
    ISSN: 0935-6304
    Keywords: GC/MS Interface ; Glass ; Open split ; HMDS glass surface deactivation ; Glass capillary columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new all-glass interface for GC/MS designed to fully exploit the potential of glass capillary columns is described. The system works in the open split mode and has high versatility with respect to column changing. It is especially suitable for mass spectrometers, which are not exclusively dedicated to GC/MS work. Two chromatograms illustrate the properties of the described interface.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020506
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