scholarly journals Disentangle Kinetic From Equilibrium Fractionation Using Primary (δ17O, δ18O, δD) and Secondary (Δ17O, dex) Stable Isotope Parameters on Samples From the Swiss Precipitation Network

2021 ◽  
Vol 9 ◽  
Author(s):  
Markus C. Leuenberger ◽  
Shyam Ranjan
Keyword(s):  
Isotope Ratio ◽  
Meteorological Parameters ◽  
Isotope Ratios ◽  
Temperature Dependent ◽  
University Of Bern ◽  
Turbulence Factor ◽  
The University ◽  
Precipitation Network ◽  
Equilibrium Fractionation ◽  
Model Approach

Since 1971 water isotope measurements are being conducted by the Climate and Environmental Physics Division at the University of Bern on precipitation, river- and groundwater collected at several places within Switzerland. The water samples were stored in glass flasks for later analyses with improved instrumentation. Conventional isotope ratio measurements on precipitated water from all stations of the network are well correlated as expected. However, Δ17O as well as dex is anticorrelated to these isotope ratio. The combination of these parameters allow to investigate dependencies on temperature, turbulence factor, and humidity of these values as well as to look into the importance and relative contributions of kinetic to equilibrium fractionations. We used published temperature dependent fractionation factors in combination with a simple Rayleigh model approach to investigate the importance of the meteorological parameters on the isotope ratios. A direct comparison of measured and modeled isotope ratios for primary (δ17O, δ18O and (δD) as well as secondary isotope parameters (Δ17O and dex) is shown.

Authenticity of sugar – Identification of plant source and determination of geographical origin of sucrose

2015 ◽  
pp. 40-43 ◽  
Author(s):  
Andreas G. Degenhardt
Keyword(s):  
Metabolic Pathways ◽  
Isotope Ratio ◽  
Geographical Origin ◽  
Hydrological Cycle ◽  
Isotope Ratios ◽  
Saccharum Officinarum ◽  
Mass Spectrometric ◽  
C3 And C4 Plants ◽  
Plant Source

The isotope ratios of water, organic matter and micronutrients from food are dependent on the circumstances and sites of their origin and production. Analytical methods, based on mass spectrometry, are established for routine determination of isotopes. Differentiation between metabolic pathways of C3 and C4 plants is realizable by determination 13C/12C ratios which can distinguish and identify sucrose from pure beet (Beta vulgaris) and pure cane (Saccharum officinarum). Influenced by the worldwide hydrological cycle the isotope ratios of 2H/1H and 18O/16O vary systematically, the variations give information about geographical origin. The exemplarily determination of authenticity is demonstrated by using mass spectrometric isotope ratio evaluation for identification of plant source and geographical origin with the help of selected sugar samples with known origin.

scholarly journals The BernClim plant phenological data set from the canton of Bern (Switzerland) 1970–2018

2019 ◽  
Vol 11 (4) ◽  
pp. 1645-1654 ◽  
Author(s):  
This Rutishauser ◽  
François Jeanneret ◽  
Robert Brügger ◽  
Yuri Brugnara ◽  
Christian Röthlisberger ◽  
...  
Keyword(s):  
Growing Season ◽  
Data Set ◽  
Urban And Regional Planning ◽  
Phenological Data ◽  
Observation Network ◽  
Good Internal Consistency ◽  
Change Impact ◽  
University Of Bern ◽  
The University

Abstract. In 1970, the Institute of Geography of the University of Bern initiated the phenological observation network BernClim. Seasonality information from plants, fog and snow was originally available for applications in urban and regional planning and agricultural and touristic suitability and is now a valuable data set for climate change impact studies. Covering the growing season, volunteer observers record the dates of key development stages of hazel (Corylus avellana), dandelion (Taraxacum officinale), apple tree (Pyrus malus) and beech (Fagus sylvatica). All observations consist of detailed site information, including location, altitude, exposition (aspect) and inclination, that makes BernClim unique in its richness in detail on decadal timescales. Quality control (QC) by experts and statistical analyses of the data have been performed to flag impossible dates, dates outside the biologically plausible range, repeated dates in the same year, stretches of consecutive identical dates and statistically inconsistent dates (outliers in time or in space). Here, we report BernClim data of 7414 plant phenological observations from 1970 to 2018 from 1304 sites at 110 stations, the QC procedure and selected applications (Rutishauser et al., 2019: https://doi.org/10.1594/PANGAEA.900102). The QC points to very good internal consistency (only 0.2 % were flagged as internally inconsistent) and likely high quality of the data. BernClim data indicate a trend towards an extended growing season. They also track the regime shift in the late 1980s well to pronounced earlier dates like numerous other phenological records across the Northern Hemisphere.

Towards SI-traceable Isotope Ratios of Greenhouse Gases

2021 ◽  
Author(s):  
Lukas Flierl ◽  
Javis Nwaboh ◽  
Olaf Rienitz ◽  
Olav Werhahn ◽  
Volker Ebert
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gases ◽  
Isotope Ratio ◽  
Isotope Ratio Mass Spectrometry ◽  
Isotope Ratios ◽  
Oxygen Isotope Ratios ◽  
Carbon And Oxygen Isotope ◽  
First Results ◽  
Buoyancy Correction ◽  
The Impact

<p>The emission of greenhouse gases and the resulting global warming is one of the most important and challenging issues of the 21<sup>st</sup> century. Carbon dioxide is one of the major contributors to the greenhouse effect and its atmospheric abundance has growing constantly since the beginning of the industrialization. The isotope ratios n(<sup>13</sup>C)/n(<sup>12</sup>C) and n(<sup>18</sup>O)/n(<sup>16</sup>O) are important tools for studying the impact of anthropogenic CO<sub>2</sub>. Usually, isotopic compositions of CO<sub>2</sub> are reported as δ-values, that express isotope ratios relative to an artifact based on a fossil calcite called VPDB. This relative VPDB scale was necessary, since absolute and SI-traceable isotope ratios of CO<sub>2</sub> are currently not available, neither by isotope ratio mass spectrometry (IRMS) nor by optical isotope ratio spectroscopy (OIRS). In this study we present a potential way of deriving absolute carbon and oxygen isotope ratios of carbon dioxide via IRMS based on the gravimetric mixture approach. Besides practical improvements like an air buoyancy correction scheme for masses of gases, we show first results applying our method which demonstrate its feasibility, limitations, and achievable uncertainties. Also, we show the mathematics behind our approach and discuss further improvements and applications. Furthermore, we show how these absolute ratios can be used in field applications by OIRS methods including a new approach on OIRS uncertainty assessments according to the GUM. For this contribution we report on our recent results within in the European metrology research projects SIRS (16ENV06). and STELLAR (19ENV05).</p>

Impact of low-degree gravity field estimation in the SLR data processing of spherical satellites at AIUB

2021 ◽  
Author(s):  
Linda Geisser ◽  
Ulrich Meyer ◽  
Daniel Arnold ◽  
Adrian Jäggi ◽  
Daniela Thaller
Keyword(s):  
Gravity Field ◽  
Lower Altitude ◽  
Earth’S Gravity Field ◽  
Low Degree ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Field Estimation ◽  
University Of Bern ◽  
The University ◽  
The Impact

<p>The Astronomical Institute of the University of Bern (AIUB) collaborates with the Federal Agency for Cartography and Geodesy (BKG) in Germany to develop new procedures to generate products for the International Laser Ranging Service (ILRS). In this framework the SLR processing of the standard ILRS weekly solutions of spherical geodetic satellites at AIUB, where the orbits are determined in 7-day arcs together with station coordinates and other geodetic parameters, is extended from LAGEOS-1/2 and the Etalon-1/2 satellites to also include the LARES satellite orbiting the Earth at much lower altitude. Since a lower orbit experiences a more variable enviroment, e.g. it is more sensitive to time-variable Earth's gravity field, the orbit parametrization has to be adapted and also the low degree spherical harmonic coefficients of Earth's gravity field have to be co-estimated. The impact of the gravity field estimation is studied by validating the quality of other geodetic parameters such as geocenter coordinates, Earth Rotation Parameters (ERPs) and station coordinates. The analysis of the influence of LARES on the SLR solution shows that a good datum definition is important.</p>

Functionalization and Homologation of Alkenes

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Hong Kong ◽  
Free Radical ◽  
Ni Catalyst ◽  
Ru Catalyst ◽  
University Of Utah ◽  
Practical Procedure ◽  
Heck Arylation ◽  
Osaka Prefecture ◽  
University Of Bern ◽  
The University

Masahito Ochiai developed (Org. Highlights, March 24, 2008) the iodosobenzene-mediated cleavage of alkenes to keto aldehydes. Thottumkara K. Vinod of Western Illinois University described (Org. Lett. 2010, 12, 5640) a modified protocol that delivered the keto acid 2. Chi-Ming Che of the University of Hong Kong established (J. Am. Chem. Soc. 2010, 132, 13229) a method for the preparative scale Fe-catalyzed cis dihydroxylation of an alkene 3. Ilhyong Ryu of Osaka Prefecture University devised (Synlett 2010, 2014) a practical procedure for the free radical addition of HBr to an alkene 5. Tetsuo Ohta of Doshisha University showed (Tetrahedron Lett. 2010, 51, 2806) that a Ru catalyst could add an aromatic acid to the internal carbon of a terminal alkene 7. Noriki Kutsumura and Takao Saito of the Tokyo University of Science found (Org. Lett. 2010, 12, 3316) conditions for bromination/dehydrobromination to convert 10 to 11. Tsuyoshi Taniguchi of Kanazawa University oxidized (J. Org. Chem. 2010, 75, 8126) the alkene 12 to the nitro alkene 13. Professor Taniguchi added (Angew. Chem. Int. Ed. 2010, 49, 10154) methyl carbazate to 14 to give the β-hydroxy ester 15. Philippe Renaud of the University of Bern effected (J. Am. Chem. Soc. 2010, 132, 17511) the free radical homologation of 16 to the azide 18. Daniel P. Becker of Loyola University described (Tetrahedron Lett. 2010, 51, 3514) the elegant diastereoselective Pd-catalyzed bis-methoxycarbonylation of 19 to the diester 20. Matthew S. Sigman of the University of Utah established (J. Am. Chem. Soc. 2010, 132, 13981) the oxidative Heck arylation of 21 to 23. F. Dean Toste of the University of California, Berkeley, found (Org. Lett. 2010, 12, 4728) that the intermediate in the gold-catalyzed alkoxylation of 24 could couple to an aryl silane 25 to give 26. Chun-Yu Ho of the Chinese University of Hong Kong used (Angew. Chem. Int. Ed. 2010, 49, 9182) a Ni catalyst to add styrene 27 to the alkene 24. Masahiro Miura of Osaka University effected (J. Org. Chem. 2010, 75, 5421) the oxidative coupling of 29 with styrene 27 to give the linear product 30.

Reactions of Alkenes

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Radical Addition ◽  
Aqueous Hydrogen Peroxide ◽  
Metal Centers ◽  
Pincer Complex ◽  
Northwestern University ◽  
Radical Reduction ◽  
Tokyo Institute ◽  
Institute Of Technology ◽  
University Of Bern ◽  
The University

Fung-E Hong of the National Chung Hsing University devised (Adv. Synth. Catal. 2011, 353, 1491) a protocol for the oxidative cleavage of an alkene 1 (or an alkyne) to the carboxylic acid 2. Patrick H. Dussault of the University of Nebraska found (Synthesis 2011, 3475) that Na triacetoxyborohydride reduced the methoxy hydroperoxide from the ozonolysis of 3 to the aldehyde 4. Reductive amination of 4 can be effected in the same pot with the same reagent. Philippe Renaud of the University of Bern used (J. Am. Chem. Soc. 2011, 133, 5913) air to promote the free radical reduction to 6 of the intermediate from the hydroboration of 5. Robert H. Grubbs of Caltech showed (Org. Lett. 2011, 13, 6429) that the phosphonium tetrafluoroborate 8 prepared by hydrophosphonation of 7 could be used directly in a subsequent Wittig reaction. Dominique Agustin of the Université de Toulouse epoxidized (Adv. Synth. Catal. 2011, 353, 2910) the alkene 9 to 10 without solvent other than the commercial aqueous t-butyl hydroperoxide. Justin M. Notestein of Northwestern University effected (J. Am. Chem. Soc. 2011, 133, 18684) cis dihydroxylation of 9 to 11 using 30% aqueous hydrogen peroxide. Chi-Ming Che of the University of Hong Kong devised (Chem. Commun. 2011, 47, 10963) a protocol for the anti-Markownikov oxidation of an alkene 12 to the aldehyde 13. Aziridines such as 14 are readily prepared from alkenes. Jeremy B. Morgan of the University of North Carolina Wilmington uncovered (Org. Lett. 2011, 13, 5444) a catalyst that rearranged 14 to the protected amino alcohol 15. A monosubstituted alkene 16 is particularly reactive both with free radicals and with coordinately unsaturated metal centers. A variety of transformations of monosubstituted alkenes have been reported. Nobuharu Iwasawa of the Tokyo Institute of Technology employed (J. Am. Chem. Soc. 2011, 133, 12980) a Pd pincer complex to catalyze the oxidative monoborylation of 16 to give 17. The 1,1-bis boryl derivatives could also be prepared. Professor Renaud effected (J. Am. Chem. Soc. 2011, 133, 13890) radical addition to 16 leading to the terminal azide 18.

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