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  • Articles  (25,083)
  • Analytical Chemistry and Spectroscopy  (25,033)
  • FID-GEO-DE-7
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  • 1
    Publication Date: 2022-11-03
    Description: For the first time a multiple connection among Expanding Earth and many phenomena of physics and cosmology.
    Description: From Earth Sciences and geoneutrino experiments Borexino and KamLAND come clues on a role of the aether in the geological evolution of Earth and planets, and of all the structures of the universe. Through the problem of the storage of the aether arriving into the heavenly bodies, hydrodynamic explanation of gravitation is found closely related to the concept of the expanding Earth. Variable radius paleogeography allows a rough evaluation of the amount of ordinary matter that is added to the planet in the time unity, and the statement of some inferences on the Earth’s inner energy balance. With the help of astrophysics the aether’s density, flow rate, and velocity are computed. The origin of the cosmological redshift and the gravitational redshift is unified to the cause of gravitation, with a concept similar, but not coincident, with that of tired light, considered very plausible by cosmologists such as Edwin Hubble and Fritz Zwicky. A superluminal aether’s speed at the Earth’s surface is found. INFN experiments confirm hydrodynamic gravitation and superluminal velocities, and it is possible to highlight an interrelations of aether parameters with the actually known cosmological parameters H0, G, c. The unification of the hydrodynamic gravitation and the expansion of the heavenly bodies, through the existence of a little dissipative force – a non- Newtonian concept – is linked to a revision of the theories of physics and cosmology, in which the actually accepted physics laws are only good approximations of a more complex reality.
    Description: INGV
    Description: Not submitted
    Description: 25
    Description: 1T. Struttura della Terra
    Description: N/A or not JCR
    Keywords: Gravitation ; Hydrodynamic Gravitation ; Redshifts ; Expanding Earth ; Earth's evolution and cosmology ; Hydrodynamic Gravitation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: manuscript
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  • 2
    Publication Date: 2022-11-22
    Description: A realistic view of the Universe
    Description: Earth Science observations and the Borexino and KamLAND geoneutrino experiments provide clues on the role of aether in the evolution of the Earth, planets, and all other universal structures. Analysis of the problem of storage of aether entering celestial bodies led to a hydrodynamic explanation of gravitation which in turn was found to be closely related to the expanding Earth and to several other phenomena. Variable radius paleogeography provides an approximate assessment of the quantity of ordinary matter added to the planet per time unit, and some inferences about the Earth’s inner energy balance. The aether density, flow rate, and velocity are computed with the help of astrophysics. The origins of cosmological and gravitational redshift are unified under the single cause of gravitation. This is linked to the similar but not interchangeable concept of tired light, which was considered very plausible by cosmologists like Edwin Hubble and Fritz Zwicky. A superluminal speed was calculated for aether at the Earth’s surface. INFN experiments confirm hydrodynamic gravitation and superluminal velocities, and it is possible to identify interrelations of aether parameters with the currently known cosmological parameters H0, G, and c . Unification of hydrodynamic gravitation and the expansion of the celestial bodies through the existence of a minor dissipative force, a non-Newtonian concept, involves a revision of the theories of physics and cosmology, in which the currently accepted laws of physics will be only considered good approximations of a more complex reality.
    Description: Silvano Gioca
    Description: Published
    Description: 1411-1439
    Description: 1T. Struttura della Terra
    Description: N/A or not JCR
    Keywords: Gravitation ; Hydrodynamic Gravitation ; Redshifts ; Expanding Earth ; Evolutionary Universe ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2016-05-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hamilton, Douglas P -- England -- Nature. 2016 May 4;533(7602):187-8. doi: 10.1038/nature17896.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of Maryland, College Park, Maryland 20742-2421, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27144360" target="_blank"〉PubMed〈/a〉
    Keywords: Astronomical Phenomena ; Astronomy/*methods ; Gravitation ; *Models, Theoretical ; *Solar System
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2015-03-18
    Description: Vertebrates have a unique 3D body shape in which correct tissue and organ shape and alignment are essential for function. For example, vision requires the lens to be centred in the eye cup which must in turn be correctly positioned in the head. Tissue morphogenesis depends on force generation, force transmission through the tissue, and response of tissues and extracellular matrix to force. Although a century ago D'Arcy Thompson postulated that terrestrial animal body shapes are conditioned by gravity, there has been no animal model directly demonstrating how the aforementioned mechano-morphogenetic processes are coordinated to generate a body shape that withstands gravity. Here we report a unique medaka fish (Oryzias latipes) mutant, hirame (hir), which is sensitive to deformation by gravity. hir embryos display a markedly flattened body caused by mutation of YAP, a nuclear executor of Hippo signalling that regulates organ size. We show that actomyosin-mediated tissue tension is reduced in hir embryos, leading to tissue flattening and tissue misalignment, both of which contribute to body flattening. By analysing YAP function in 3D spheroids of human cells, we identify the Rho GTPase activating protein ARHGAP18 as an effector of YAP in controlling tissue tension. Together, these findings reveal a previously unrecognised function of YAP in regulating tissue shape and alignment required for proper 3D body shape. Understanding this morphogenetic function of YAP could facilitate the use of embryonic stem cells to generate complex organs requiring correct alignment of multiple tissues.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720436/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720436/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Porazinski, Sean -- Wang, Huijia -- Asaoka, Yoichi -- Behrndt, Martin -- Miyamoto, Tatsuo -- Morita, Hitoshi -- Hata, Shoji -- Sasaki, Takashi -- Krens, S F Gabriel -- Osada, Yumi -- Asaka, Satoshi -- Momoi, Akihiro -- Linton, Sarah -- Miesfeld, Joel B -- Link, Brian A -- Senga, Takeshi -- Castillo-Morales, Atahualpa -- Urrutia, Araxi O -- Shimizu, Nobuyoshi -- Nagase, Hideaki -- Matsuura, Shinya -- Bagby, Stefan -- Kondoh, Hisato -- Nishina, Hiroshi -- Heisenberg, Carl-Philipp -- Furutani-Seiki, Makoto -- P30 EY001931/EY/NEI NIH HHS/ -- R01 EY014167/EY/NEI NIH HHS/ -- R01 EY016060/EY/NEI NIH HHS/ -- R01EY014167/EY/NEI NIH HHS/ -- Medical Research Council/United Kingdom -- England -- Nature. 2015 May 14;521(7551):217-21. doi: 10.1038/nature14215. Epub 2015 Mar 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK. ; Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan. ; IST Austria, Am Campus 1, A-3400 Klosterneuburg, Austria. ; Department of Genetics and Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan. ; Department of Molecular Biology, School of Medicine, Keio University, Tokyo 160-8582, Japan. ; Japan Science and Technology Agency (JST), ERATO-SORST Kondoh Differentiation Signaling Project, Kyoto 606-8305, Japan. ; Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. ; Division of Cancer Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan. ; Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7FY, UK. ; 1] Japan Science and Technology Agency (JST), ERATO-SORST Kondoh Differentiation Signaling Project, Kyoto 606-8305, Japan [2] Graduate School of Frontier Bioscience, Osaka University, Osaka 565-0871, Japan [3] Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan. ; 1] Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK [2] Japan Science and Technology Agency (JST), ERATO-SORST Kondoh Differentiation Signaling Project, Kyoto 606-8305, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25778702" target="_blank"〉PubMed〈/a〉
    Keywords: Actomyosin/metabolism ; Adaptor Proteins, Signal Transducing/genetics/metabolism ; Animals ; Body Size/*genetics ; Embryo, Nonmammalian/anatomy & histology/embryology/metabolism ; Fish Proteins/genetics/*metabolism ; GTPase-Activating Proteins/metabolism ; Genes, Essential/genetics ; Gravitation ; Humans ; Morphogenesis/*genetics ; Mutation/genetics ; Organ Size/genetics ; Oryzias/*anatomy & histology/*embryology/genetics ; Phenotype ; Protein-Serine-Threonine Kinases/genetics/metabolism ; Signal Transduction ; Spheroids, Cellular/cytology/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2013-03-16
    Description: Determining the atmospheric structure and chemical composition of an exoplanet remains a formidable goal. Fortunately, advancements in the study of exoplanets and their atmospheres have come in the form of direct imaging--spatially resolving the planet from its parent star--which enables high-resolution spectroscopy of self-luminous planets in jovian-like orbits. Here, we present a spectrum with numerous, well-resolved molecular lines from both water and carbon monoxide from a massive planet orbiting less than 40 astronomical units from the star HR 8799. These data reveal the planet's chemical composition, atmospheric structure, and surface gravity, confirming that it is indeed a young planet. The spectral lines suggest an atmospheric carbon-to-oxygen ratio that is greater than that of the host star, providing hints about the planet's formation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Konopacky, Quinn M -- Barman, Travis S -- Macintosh, Bruce A -- Marois, Christian -- New York, N.Y. -- Science. 2013 Mar 22;339(6126):1398-401. doi: 10.1126/science.1232003. Epub 2013 Mar 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada. konopacky@di.utoronto.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23493423" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; *Carbon Monoxide ; *Evolution, Planetary ; Extraterrestrial Environment ; Gravitation ; *Planets ; Spectrum Analysis ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2012-06-30
    Description: We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k(2) = 0.589 +/- 0.150 and k(2) = 0.637 +/- 0.224 (2sigma). Such a large response to the tidal field requires that Titan's interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iess, Luciano -- Jacobson, Robert A -- Ducci, Marco -- Stevenson, David J -- Lunine, Jonathan I -- Armstrong, John W -- Asmar, Sami W -- Racioppa, Paolo -- Rappaport, Nicole J -- Tortora, Paolo -- New York, N.Y. -- Science. 2012 Jul 27;337(6093):457-9. doi: 10.1126/science.1219631. Epub 2012 Jun 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dipartimento di Ingegneria Meccanica e Aerospaziale, Universita La Sapienza, via Eudossiana 18, 00184 Rome, Italy. luciano.iess@uniroma1.it〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22745254" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Gravitation ; Ice ; *Saturn ; Spacecraft ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2010-03-13
    Description: Precise radio tracking of the spacecraft Cassini has provided a determination of Titan's mass and gravity harmonics to degree 3. The quadrupole field is consistent with a hydrostatically relaxed body shaped by tidal and rotational effects. The inferred moment of inertia factor is about 0.34, implying incomplete differentiation, either in the sense of imperfect separation of rock from ice or a core in which a large amount of water remains chemically bound in silicates. The equilibrium figure is a triaxial ellipsoid whose semi-axes a, b, and c differ by 410 meters (a-c) and 103 meters (b-c). The nonhydrostatic geoid height variations (up to 19 meters) are small compared to the observed topographic anomalies of hundreds of meters, suggesting a high degree of compensation appropriate to a body that has warm ice at depth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iess, Luciano -- Rappaport, Nicole J -- Jacobson, Robert A -- Racioppa, Paolo -- Stevenson, David J -- Tortora, Paolo -- Armstrong, John W -- Asmar, Sami W -- New York, N.Y. -- Science. 2010 Mar 12;327(5971):1367-9. doi: 10.1126/science.1182583.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dipartimento di Ingegneria Aerospaziale ed Astronautica, Universita La Sapienza, via Eudossiana 18, 00184 Rome, Italy. luciano.iess@uniroma1.it〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20223984" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Gravitation ; Ice ; *Saturn ; Spacecraft ; Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 8
    Publication Date: 2010-09-11
    Description: Plants and animals produce modular developmental units in a periodic fashion. In plants, lateral roots form as repeating units along the root primary axis; however, the developmental mechanism regulating this process is unknown. We found that cyclic expression pulses of a reporter gene mark the position of future lateral roots by establishing prebranch sites and that prebranch site production and root bending are periodic. Microarray and promoter-luciferase studies revealed two sets of genes oscillating in opposite phases at the root tip. Genetic studies show that some oscillating transcriptional regulators are required for periodicity in one or both developmental processes. This molecular mechanism has characteristics that resemble molecular clock-driven activities in animal species.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2976612/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2976612/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Moreno-Risueno, Miguel A -- Van Norman, Jaimie M -- Moreno, Antonio -- Zhang, Jingyuan -- Ahnert, Sebastian E -- Benfey, Philip N -- R01 GM043778/GM/NIGMS NIH HHS/ -- R01 GM043778-19/GM/NIGMS NIH HHS/ -- R01 GM043778-20/GM/NIGMS NIH HHS/ -- R01 GM043778-21/GM/NIGMS NIH HHS/ -- R01-GM043778/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2010 Sep 10;329(5997):1306-11. doi: 10.1126/science.1191937.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology and Institute for Genome Sciences and Policy Center for Systems Biology, Duke University, Durham, NC 27708, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20829477" target="_blank"〉PubMed〈/a〉
    Keywords: Arabidopsis/cytology/*genetics/*growth & development/metabolism ; Arabidopsis Proteins/genetics/metabolism ; Gene Expression Profiling ; *Gene Expression Regulation, Plant ; Gene Regulatory Networks ; Genes, Plant ; Genes, Reporter ; Gravitation ; Indoleacetic Acids/metabolism/pharmacology ; Meristem/*genetics/*growth & development/metabolism ; Oligonucleotide Array Sequence Analysis ; Phthalimides/pharmacology ; Plant Roots/cytology/genetics/*growth & development ; Promoter Regions, Genetic ; Signal Transduction ; Temperature ; Time Factors ; Transcription Factors/genetics/metabolism ; Transcription, Genetic
    Print ISSN: 0036-8075
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  • 9
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    Nature Publishing Group (NPG)
    Publication Date: 2010-07-31
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kwok, Roberta -- England -- Nature. 2010 Jul 29;466(7306):540-1. doi: 10.1038/466540a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20671681" target="_blank"〉PubMed〈/a〉
    Keywords: Earth (Planet) ; Gravitation ; *Meteoroids ; *Minor Planets ; *Moon ; Time Factors ; Water/analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2010-01-16
    Description: Wetlands are the largest individual source of methane (CH4), but the magnitude and distribution of this source are poorly understood on continental scales. We isolated the wetland and rice paddy contributions to spaceborne CH4 measurements over 2003-2005 using satellite observations of gravity anomalies, a proxy for water-table depth Gamma, and surface temperature analyses TS. We find that tropical and higher-latitude CH4 variations are largely described by Gamma and TS variations, respectively. Our work suggests that tropical wetlands contribute 52 to 58% of global emissions, with the remainder coming from the extra-tropics, 2% of which is from Arctic latitudes. We estimate a 7% rise in wetland CH4 emissions over 2003-2007, due to warming of mid-latitude and Arctic wetland regions, which we find is consistent with recent changes in atmospheric CH4.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bloom, A Anthony -- Palmer, Paul I -- Fraser, Annemarie -- Reay, David S -- Frankenberg, Christian -- New York, N.Y. -- Science. 2010 Jan 15;327(5963):322-5. doi: 10.1126/science.1175176.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of GeoSciences, University of Edinburgh, Edinburgh, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20075250" target="_blank"〉PubMed〈/a〉
    Keywords: Archaea/metabolism ; Atmosphere/*chemistry ; *Crops, Agricultural/growth & development ; Geography ; Gravitation ; Methane/*analysis/biosynthesis ; *Oryza/growth & development ; Seasons ; Spacecraft ; Temperature ; Tropical Climate ; *Wetlands
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2010-03-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sohl, Frank -- New York, N.Y. -- Science. 2010 Mar 12;327(5971):1338-9. doi: 10.1126/science.1186255.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany. frank.sohl@dlr.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20223976" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Gravitation ; Ice ; *Saturn ; Spacecraft ; Water
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  • 12
    Publication Date: 2010-11-13
    Description: Animals have developed a range of drinking strategies depending on physiological and environmental constraints. Vertebrates with incomplete cheeks use their tongue to drink; the most common example is the lapping of cats and dogs. We show that the domestic cat (Felis catus) laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue. A combined experimental and theoretical analysis reveals that Felis catus exploits fluid inertia to defeat gravity and pull liquid into the mouth. This competition between inertia and gravity sets the lapping frequency and yields a prediction for the dependence of frequency on animal mass. Measurements of lapping frequency across the family Felidae support this prediction, which suggests that the lapping mechanism is conserved among felines.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reis, Pedro M -- Jung, Sunghwan -- Aristoff, Jeffrey M -- Stocker, Roman -- New York, N.Y. -- Science. 2010 Nov 26;330(6008):1231-4. doi: 10.1126/science.1195421. Epub 2010 Nov 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21071630" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Cats/*physiology ; Drinking/*physiology ; Felidae/physiology ; Gravitation ; Models, Biological ; Movement ; Physical Processes ; Tongue/*physiology
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  • 13
    Publication Date: 2009-02-21
    Description: Thin layers of phytoplankton are important hotspots of ecological activity that are found in the coastal ocean, meters beneath the surface, and contain cell concentrations up to two orders of magnitude above ambient concentrations. Current interpretations of their formation favor abiotic processes, yet many phytoplankton species found in these layers are motile. We demonstrated that layers formed when the vertical migration of phytoplankton was disrupted by hydrodynamic shear. This mechanism, which we call gyrotactic trapping, can be responsible for the thin layers of phytoplankton commonly observed in the ocean. These results reveal that the coupling between active microorganism motility and ambient fluid motion can shape the macroscopic features of the marine ecological landscape.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Durham, William M -- Kessler, John O -- Stocker, Roman -- New York, N.Y. -- Science. 2009 Feb 20;323(5917):1067-70. doi: 10.1126/science.1167334.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19229037" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Cell Shape ; Chlamydomonas/cytology/*physiology ; *Ecosystem ; Flagella ; Gravitation ; Movement ; Phytoplankton/cytology/*physiology ; *Water ; *Water Movements
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  • 14
    Publication Date: 2017-04-04
    Description: In May 1994 a first comparison campaign between a superconducting and the IMGC absolute gravimeter has been performed in Brasimone, near Bologna in Italy. The superconducting gravimeter was previously calibrated by means of a moving ring, the mass of which has been measured with the highest accuracy allowed by the actual technology. During the three days of observation with the absolute gravity meter, a maximum, a complete semidiurnal curve and a minimum of the tidal effect has been observed. These data have been used to compute the calibration factor of the superconducting gravity meter; it agrees in a rather satisfactory way with the results of the calibration with the moving mass.
    Description: Published
    Description: 27-36
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: reserved
    Keywords: Gravity ; Gravitation ; Earth Tides ; Gravimeters ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 15
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    Dr. Olivier Francis - Observatoire Royal de Belgique - Avenue Circulaire 3 - 1180 Bruxelles - Belgium
    Publication Date: 2017-04-04
    Description: From 1990 up to now a superconducting gravimeter GWR model TT70 is operating in a laboratory located on the dismissed nuclear power plant of Brasimone, in the italian Apoennines between Bologna and Florence, in the frame of an experiment meant to verify Newton's gravitational law. From july 1995, the gravimeter is involved in the Global Geodynamics Project, and is actually working for high precision tidal analysis and modelling. In this paper we describe the calibration procedure adopted together with the preliminary results of the tidal analysis performed using yhe software Eterna 3.20.
    Description: Published
    Description: 9816-9825
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: N/A or not JCR
    Description: open
    Keywords: Gravity ; Gravitation ; Earth Tides ; Gravimeters ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-04
    Description: A geophysical experiment consisting of the measurements of the gravitational effect produced by a large water mass was performed in order to verify the Newton's law. The use of a superconducting gravimeter, the detailed analysis of the local tidal perturbation, the precise topographic and geological surveys lead to a precision of about 0.1% in the final result. The ratio between the measured and the expected gravitational effect differs from 1 by more than 9 standard deviations. This may be explained by adding to the Newtonian potential a Yukawa repulsive term. The experimental result leads to constraints for the relationship between the relative magnitude (alpha)of the new term and the range (lambda) of the interaction. In the region 20 m 〈 lambda 〉 500m, alpha ranges from 2.6% to 1.3%.
    Description: Published
    Description: 775-804
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: Gravity ; Gravitation ; Newton's law ; gravimeters ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 17
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2006-12-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2006 Dec 22;314(5807):1850-1.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17185567" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Birds ; Cosmic Radiation ; Electric Conductivity ; Gravitation ; Helium/chemistry ; Humans ; Influenza A Virus, H5N1 Subtype ; Influenza in Birds/epidemiology/virology ; Influenza, Human/epidemiology/virology ; Microbiology ; RNA Interference ; *Science ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 18
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2005-04-02
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alexander, R McNeill -- New York, N.Y. -- Science. 2005 Apr 1;308(5718):58-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Biology, University of Leeds, Leeds LS2 9JT, UK. r.m.alexander@leeds.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15802589" target="_blank"〉PubMed〈/a〉
    Keywords: Biomechanical Phenomena ; Energy Metabolism ; Gravitation ; Humans ; Models, Anatomic ; Oxygen Consumption ; *Robotics ; *Walking/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 19
    Publication Date: 2005-02-19
    Description: Passive-dynamic walkers are simple mechanical devices, composed of solid parts connected by joints, that walk stably down a slope. They have no motors or controllers, yet can have remarkably humanlike motions. This suggests that these machines are useful models of human locomotion; however, they cannot walk on level ground. Here we present three robots based on passive-dynamics, with small active power sources substituted for gravity, which can walk on level ground. These robots use less control and less energy than other powered robots, yet walk more naturally, further suggesting the importance of passive-dynamics in human locomotion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Collins, Steve -- Ruina, Andy -- Tedrake, Russ -- Wisse, Martijn -- New York, N.Y. -- Science. 2005 Feb 18;307(5712):1082-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Mechanical Engineering, University of Michigan, Ann Arbor, MI 48104, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15718465" target="_blank"〉PubMed〈/a〉
    Keywords: Algorithms ; Biomechanical Phenomena ; Electric Power Supplies ; Energy Metabolism ; Gait ; Gravitation ; Humans ; Motion ; Oxygen Consumption ; *Robotics ; *Walking
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 20
    Publication Date: 2005-05-28
    Description: Radio Doppler data from the Galileo spacecraft's encounter with Amalthea, one of Jupiter's small inner moons, on 5 November 2002 yield a mass of (2.08 +/- 0.15) x 10(18) kilograms. Images of Amalthea from two Voyager spacecraft in 1979 and Galileo imaging between November 1996 and June 1997 yield a volume of (2.43 +/- 0.22) x 10(6) cubic kilometers. The satellite thus has a density of 857 +/- 99 kilograms per cubic meter. We suggest that Amalthea is porous and composed of water ice, as well as rocky material, and thus formed in a cold region of the solar system, possibly not at its present location near Jupiter.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anderson, John D -- Johnson, Torrence V -- Schubert, Gerald -- Asmar, Sami -- Jacobson, Robert A -- Johnston, Douglas -- Lau, Eunice L -- Lewis, George -- Moore, William B -- Taylor, Anthony -- Thomas, Peter C -- Weinwurm, Gudrun -- New York, N.Y. -- Science. 2005 May 27;308(5726):1291-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA. john.d.anderson@jpl.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15919987" target="_blank"〉PubMed〈/a〉
    Keywords: Gravitation ; Ice ; *Jupiter ; Pressure ; Spacecraft ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 21
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2005-12-24
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2005 Dec 23;310(5756):1885.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16373543" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Birds ; Cosmic Radiation ; Environmental Microbiology ; Gravitation ; Humans ; Physical Phenomena ; Physics ; Rna ; Research/*trends
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 22
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-09-09
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fortney, Jonathan J -- New York, N.Y. -- Science. 2004 Sep 3;305(5689):1414-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Planetary Systems Branch, NASA Ames Research Center, Moffett Field, CA 94035, USA. jfortney@arc.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15353790" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; *Evolution, Planetary ; Gravitation ; *Helium ; *Hydrogen ; *Jupiter ; Mathematics ; Models, Structural ; Pressure ; *Saturn ; Spacecraft ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 23
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-04-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dehant, Veronique -- New York, N.Y. -- Science. 2003 Apr 11;300(5617):260-1.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12690177" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; Evolution, Planetary ; Gravitation ; *Mars ; Pressure ; Temperature
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 24
    Publication Date: 2003-03-08
    Description: The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yoder, C F -- Konopliv, A S -- Yuan, D N -- Standish, E M -- Folkner, W M -- New York, N.Y. -- Science. 2003 Apr 11;300(5617):299-303. Epub 2003 Mar 6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. Charles.F.Yoder@jpl.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12624177" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; *Dry Ice ; Gravitation ; *Mars ; Mathematics ; Pressure ; Rotation ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 25
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-05-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lawler, Andrew -- New York, N.Y. -- Science. 2003 May 2;300(5620):727.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12730573" target="_blank"〉PubMed〈/a〉
    Keywords: Evolution, Planetary ; Extraterrestrial Environment ; Gravitation ; Ice ; *Moon ; *Space Flight
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 26
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-07-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stone, Richard -- New York, N.Y. -- Science. 2003 Jul 11;301(5630):152.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12855780" target="_blank"〉PubMed〈/a〉
    Keywords: Biological Evolution ; England ; Fossils ; Gravitation ; History, 17th Century ; Natural History/history ; Physics/history ; Science/*history
    Print ISSN: 0036-8075
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  • 27
    Publication Date: 2002-12-03
    Description: The evolution of gravitationally unstable protoplanetary gaseous disks has been studied with the use of three-dimensional smoothed particle hydrodynamics simulations with unprecedented resolution. We have considered disks with initial masses and temperature profiles consistent with those inferred for the protosolar nebula and for other protoplanetary disks. We show that long-lasting, self-gravitating protoplanets arise after a few disk orbital periods if cooling is efficient enough to maintain the temperature close to 50 K. The resulting bodies have masses and orbital eccentricities similar to those of detected extrasolar planets.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mayer, Lucio -- Quinn, Thomas -- Wadsley, James -- Stadel, Joachim -- New York, N.Y. -- Science. 2002 Nov 29;298(5599):1756-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of Washington, Seattle, WA 98195, USA. lucio@physik.unizh.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12459581" target="_blank"〉PubMed〈/a〉
    Keywords: Computer Simulation ; *Evolution, Planetary ; Gases ; Gravitation ; Hydrogen ; Jupiter ; *Planets
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 28
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-12-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kerr, Richard A -- New York, N.Y. -- Science. 2002 Nov 29;298(5599):1698-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12459562" target="_blank"〉PubMed〈/a〉
    Keywords: Computer Simulation ; *Evolution, Planetary ; Gases ; Gravitation ; *Jupiter ; *Saturn
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 29
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-02-07
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kerr, R A -- New York, N.Y. -- Science. 2000 Mar 10;287(5459):1727-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10755919" target="_blank"〉PubMed〈/a〉
    Keywords: *Evolution, Planetary ; *Extraterrestrial Environment ; Geologic Sediments ; Gravitation ; *Mars ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 30
    Publication Date: 2001-04-03
    Description: Loading of the lithosphere of Mars by the Tharsis rise explains much of the global shape and long-wavelength gravity field of the planet, including a ring of negative gravity anomalies and a topographic trough around Tharsis, as well as gravity anomaly and topographic highs centered in Arabia Terra and extending northward toward Utopia. The Tharsis-induced trough and antipodal high were largely in place by the end of the Noachian Epoch and exerted control on the location and orientation of valley networks. The release of carbon dioxide and water accompanying the emplacement of approximately 3 x 10(8) cubic kilometers of Tharsis magmas may have sustained a warmer climate than at present, enabling the formation of ancient valley networks and fluvial landscape denudation in and adjacent to the large-scale trough.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Phillips, R J -- Zuber, M T -- Solomon, S C -- Golombek, M P -- Jakosky, B M -- Banerdt, W B -- Smith, D E -- Williams, R M -- Hynek, B M -- Aharonson, O -- Hauck , S A 2nd -- New York, N.Y. -- Science. 2001 Mar 30;291(5513):2587-91. Epub 2001 Mar 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉McDonnell Center for the Space Sciences and Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11283367" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; *Carbon Dioxide ; *Evolution, Planetary ; Extraterrestrial Environment ; Gravitation ; *Mars ; *Water
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 31
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-10-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stevenson, D J -- New York, N.Y. -- Science. 2001 Oct 5;294(5540):71-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. djs@gps.caltech.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11588243" target="_blank"〉PubMed〈/a〉
    Keywords: Evolution, Planetary ; Extraterrestrial Environment ; Gravitation ; Ice ; *Jupiter
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 32
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2001-12-12
    Description: Using topography collected over one martian year from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor (MGS) spacecraft, we have measured temporal changes in the elevation of the martian surface that correlate with the seasonal cycle of carbon dioxide exchange between the surface and atmosphere. The greatest elevation change (1.5 to 2 meters) occurs at high latitudes ( above 80 degrees ), whereas the bulk of the mass exchange occurs at lower latitudes (below 75 degrees N and below 73 degrees S). An unexpected period of sublimation was observed during northern hemisphere autumn, coincident with dust storms in the southern hemisphere. Analysis of MGS Doppler tracking residuals revealed temporal variations in the flattening of Mars that correlate with elevation changes. The combined changes in gravity and elevation constrain the average density of seasonally deposited carbon dioxide to be 910 +/- 230 kilograms per cubic meter, which is considerably denser than terrestrial snow.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, D E -- Zuber, M T -- Neumann, G A -- New York, N.Y. -- Science. 2001 Dec 7;294(5549):2141-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory for Terrestrial Physics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11739951" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; *Carbon Dioxide ; *Dry Ice ; Extraterrestrial Environment ; Gravitation ; *Mars ; Seasons ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 33
    Electronic Resource
    Electronic Resource
    Springer
    General relativity and gravitation 32 (2000), S. 1255-1269 
    ISSN: 1572-9532
    Keywords: Gravitation ; cosmology ; anisotropy ; above-barrier reflection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The classical and quantum evolution of an anisotropic cosmological Bianchi type I model is considered. In the classical case, the influence of the minimally coupled scalar field is taken into account. Thus the system of two equations is obtained, which are explored at the inflationary and scalaron stages. The quantum problem in view of the positive cosmological constant is considered. The principal moment of the account of an anisotropy is the occurrence of the potential barrier unbounded in zero and at infinity. Though the greatest value of the potential is less than zero and the total energy of the Universe E=0, there is an important opportunity for above-barrier reflection of the wave function of the Universe. After reflection the wave function describes the expanding Universe promptly losing anisotropy and transferring into the Friedmann Universe.
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  • 34
    ISSN: 0935-6304
    Keywords: Proteomics ; protein analysis ; multidimensional HPLC ; ion-exchange chromatography ; reversed phase chromatography ; comprehensive HPLC ; two-dimensional HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The interactive modes of High Performance Liquid Chromatography (HPLC) of proteins provide a platform for the construction of a multidimensional HPLC system coupled to mass spectrometry. We present a system composed of both anion and cation exchanger columns, in the first dimension, and n-octadecyl bonded 1.5 μm nonporous silica columns in the second dimension. Both columns are operated under gradient conditions. A system suitability test with standard proteins showed that the total analysis can be performed within about 20 minutes. The fractions taken from the ion exchanger column are directly analyzed within one minute on the reversed phase column at a high flow rate. Two reversed phase columns are applied and operated alternatively: while the first column performs the separation within one minute, the analytes leaving the first dimension are enriched in an on-column focusing mode on top of the second column. The sample clean-up and enrichment is performed on a novel type of restricted access cation exchanger column with internal sulfonic acid groups and external diol groups. The columns exhibit a molecular weight exclusion limit for globular proteins of about 15 kDa. Our next studies will be directed towards the analysis of proteins and peptides from extracts of fibroblasts.
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  • 35
    ISSN: 0935-6304
    Keywords: μLC ; FID ; LC-FID ; carbohydrates ; amino acids ; alcohols ; phosphonic acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The potential of the on-line coupling of microcolumn liquid chromatography (μLC) using aqueous eluents with a flame ionization detector (FID) was evaluated. An eluent-jet interface was modified to allow the efficient introduction of the eluent into the FID. The potential of the method is demonstrated by the μLC-FID determination of lower alcohols and bis(2-hydroxyethylthio)alkanes on porous and non-porous stationary phases, respectively. Flow injection analysis (FIA)-FID experiments with highly polar, thermolabile, semi-volatile and non-volatile compounds like amino acids, organic acids, alkylphosphonic acids, and carbohydrates showed the developed configuration to be a promising approach for the detection of a wide range of analytes. Compared with a nebulization interface, the eluent-jet interface showed 4-10 times higher peaks for citric acid. Detection limits by FIA for all compounds were in the range of 0.2-5 ng injected. With ribose as test compound, plots of peak height vs. amount injected showed good linearity (r2 〉 0.999) in the range of 75-12,000 μg/mL. The repeatability showed relative standard deviations of less than 5%.
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  • 36
    ISSN: 0935-6304
    Keywords: Artemisia palustris ; Asterothamnus centrali-asiaticus ; capillary gas liquid chromatography ; Compositae (Asteraceae) ; Heteropappus hispidus ; seed oil ; silver ion thin layer chromatography ; trans-fatty acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Seed oils from the Compositae plant family are known to contain a variety of unusual fatty acids. Subsequent to the recent discovery of γ-linolenic acid in Saussurea and Youngia, further Mongolian Compositae species were investigated for their seed oil fatty acid composition. A number of δ3trans-fatty acids (16 : 1δ3t, 18 : 1δ3t and 18 : 3δ3t, 9c, 12c) were found in the seed oils of Heteropappus hispidus and Asterothamnus centrali-asiaticus. The latter fatty acid, but not the trans-monoenes, was also found in one species of Artemisia. These unusual fatty acid isomers were characterized by capillary gas-liquid chromatographic (GLC) separations in combination with other chromatographic techniques (analytical thin layer chromatography, TLC and preparative argentation TLC), and infrared spectrocsopy (IR). Their identity was further confirmed by co-chromatography with other seed oils known to contain these trans-fatty acids. The fact that within the Compositae plant family there are apparently two or three distinct groups of genera containing δ3trans-fatty acids is discussed.
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  • 37
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 386-388 
    ISSN: 0935-6304
    Keywords: On-line SFE-SFC ; organometallics ; purity testing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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  • 38
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 397-400 
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction ; capillary GC ; hydrocarbons ; bio-oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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  • 39
    ISSN: 0935-6304
    Keywords: Clean-up ; aliphatic hydrocarbons ; organochlorine compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 40
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 430-436 
    ISSN: 0935-6304
    Keywords: Speciation ; digestion ; capillary electrophoresis ; ferrous ; ferric ; mineral analysis ; complexation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Capillary electrophoresis is used as a means of cation separation for cationic speciation analysis. Acceptable separation of ferrous and ferric iron was achieved by using a mixed complexing agent run buffer which gave stable species in solution. These iron species, and total iron, were determined simultaneously in certified reference materials with a single digestion step. A variety of digestion techniques were compared, primarily for their non-oxidative capabilities in order to preserve the oxidation state of iron in the mineral samples. The most favorable recoveries resulted from a continuous flow nitrogen purge technique. Total iron levels obtained from the CE method were compared with those determined by two spectroscopic techniques, with similar results obtained using the different instrumental methods.
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  • 41
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    Journal of High Resolution Chromatography 23 (2000), S. 413-429 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; enantiomer separation ; chiral drugs ; TM-γ-cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---High-throughput screening is a promising new approach in analytical chemistry. Within the framework of an extended screening program (The German-Chinese Drug Screening Program), the enantioseparation of 86 drugs was investigated by capillary zone electrophoresis in the presence of the chiral solvating agent (CSA) octakis-(2,3,6-tri-O-methyl)-γ-cyclodextrin (TM-γ-CD). By this means, 15 drugs could be separated into enantiomeric pairs. Approximate measures for the degree of interaction (migration retardation factor, Rm) and for the degree of enantiomer recognition (migration separation factors, αm) revealed intriguing patterns that were compared with those found for native γ-cyclodextrin (γ-CD). Although there is a distinct influence of the analyte structure on the electrophoretic data, interpretation remains difficult. Most remarkably, permethylation of γ-CD leads neither to a higher affinity nor to better chiral recognition, in contrast to the findings with α-CD.
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  • 42
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    Journal of High Resolution Chromatography 23 (2000), S. 445-448 
    ISSN: 0935-6304
    Keywords: O-Aryl,O-(1-methylthioethylideneamino)phosphates ; retention prediction ; quantitative structure-retention relationship (QSRR) ; reversed-phase HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Using factor analysis and stepwise linear regression methods, two parameters - CMR and ECCR - were selected from eight solute-related structure parameters as the most retention-influencing parameters. The relationships between the retention data (k ´) and the two structure parameters were established for 13 O-aryl,O-(1-methylthioethylideneamino)phosphate compounds under a wide range of experimental conditions. The retention data (k ´) of another seven compounds with similar structures were predicted using these QSRR equations. Good agreement was obtained between the experimental k ´ values and predicted ones.
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  • 43
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    Journal of High Resolution Chromatography 23 (2000), S. 525-530 
    ISSN: 0935-6304
    Keywords: Packed capillary liquid chromatography ; temperature programming ; Fourier-transform infrared spectroscopy ; polymer additives ; pneumatic nebulization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Temperature-programmed packed capillary liquid chromatography has been coupled off-line to Fourier-transform infrared spectroscopy, utilizing a commercially available interface with a pneumatic nebulizer rebuilt to handle low flow rates at elevated temperatures. The modified interface showed excellent performance with regard to non-aqueous reversed phase separations of polymer additives, resulting in constructed Gram-Schmidt chromatograms comparable to chromatograms obtained using UV detection. The spray of the in-house constructed nebulizer was not influenced by temperature changes of the column effluent, and hence temperature-programmed gradient separations could be used successfully. The relative standard deviation of peak height was 4.4% (n = 5) and the mass limit of detection was determined to be about 40 ng, using a polymer antioxidant as model compound. The present instrumental coupling has been used for characterization of the antioxidant Irgafos P-EPQ.
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  • 44
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    Journal of High Resolution Chromatography 23 (2000), S. 531-538 
    ISSN: 0935-6304
    Keywords: Capillary isotachophoresis ; capillary electrophoresis ; column-coupling electrophoresis ; enantiomers ; chiral ; amino acids ; tryptophan ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The ability of capillary zone electrophoresis (CZE) coupled on-line with capillary isotachophoresis (ITP) sample pretreatment in the column-coupling capillary electrophoresis equipment to separate trace enantiomers present in samples of complex ionic matrices and enantiomers present in their mixtures at significantly differing concentrations has been studied. Enantiomers of 2,4-dinitrophenyl labeled norleucine (DNP-Nleu) and tryptophan enantiomers were employed as model analytes in this work while urine and mixtures of tryptophan enantiomers of differing concentrations served as model samples. Experiments performed with urine samples spiked with the DNP-Nleu racemate at sub-μmol/L concentrations demonstrated excellent sample pretreatment capabilities of ITP (concentration of the analytes, in-column and post-column sample clean up) when coupled on-line with chiral CZE separations. In the CZE separations of enantiomers present in the samples at trace concentrations the sample pretreatment could be performed in both achiral and chiral ITP electrolyte systems. The use of a chiral electrolyte system was found to be essential in the ITP pretreatment of the samples containing the enantiomers at very differing concentrations. For example, a 2×10-7 mol/L concentration of L-tryptophan could be detected in the CZE separation stage of the ITP-CZE combination in samples containing about a 104 excess of D-tryptophan only when the ITP pretreatment was carried out in the electrolyte system providing the resolution of enantiomers (α-cyclodextrin served for this purpose in the present work). A post-column ITP sample clean up was found effective in enhancing the destacking rate of the trace enantiomer in the CZE stage when the migration configuration of the enantiomers was less favorable (the trace constituent migrating behind the major enantiomer).
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  • 45
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    Journal of High Resolution Chromatography 23 (2000), S. 554-560 
    ISSN: 0935-6304
    Keywords: Comprehensive gas chromatography ; multidimensional gas chromatography ; essential oils ; coupled column analysis ; high resolution analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The essential oils from French lavender (Lavandula angustifolia) and tea tree (Melaleuca alternifolia) were separated by the two-dimensional GC technique of comprehensive gas chromatography. A coupled column combination of non-polar (5% phenyl equivalent) and polyethylene glycol phase columns was used to provide the desired resolution performance. By using a range of known standards, some of the peaks in lavender oil can be assigned. Some of these also occur in tea tree oil; however, from our knowledge of the major constituents in this oil and their relative retention behaviour, most of the major peaks may be tentatively assigned within the 2-dimensional separation space. There appear to be elution patterns within the 2-D space which should be useful in correlating retention with chemical and structural properties of the components, although this will require further evaluation. A range of coeluting peaks, which may not be so readily separated by using a single column capillary GC analysis, are resolved in the experiment described.
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  • 46
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    Journal of High Resolution Chromatography 23 (2000), S. 565-566 
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; zinc dithiocarbamate ; vulcanization accelerator ; rubber gloves ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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  • 47
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    Journal of High Resolution Chromatography 23 (2000), S. 603-608 
    ISSN: 0935-6304
    Keywords: Solvation parameter model ; ystem constants for poly(dimethyldiphenylsiloxane) HP-5 and poly(ethylene glycol) HP-INNOWax stationary phases ; temperature ; molecular interaction ; retention models ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 48
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    Journal of High Resolution Chromatography 23 (2000), S. 619-627 
    ISSN: 0935-6304
    Keywords: Enantiomer separation ; mixed chiral selectors ; modified cyclodextrins ; gas chromatography ; PCB ; o,p´-DDD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Columns containing different types of cyclodextrin derivatives have been evaluated for chiral gas chromatographic separation of atropisomeric PCBs, o,p´-DDT and o,p´-DDD. Separation was attempted on columns containing mixed chiral selectors, and the performance of two closely related selectors was also examined. The cyclodextrins were: permethylated-β-CD (PM-β-CD), heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-CD (2,3-M-6-TBDMS-β-CD), heptakis(2,3-di-O-methyl-6-O-tert-hexyldimethylsilyl)-β-CD (2,3-M-6-THDMS-β-CD), and heptakis(2,3-di-O-ethyl-6-O-tert-hexyldimethylsilyl)-β-cyclodextrin (2,3-E-6-THDMS-β-CD). The cyclodextrins were dissolved in OV-1701 or in a dimethylsiloxane/silarylene copolymer containing 5% phenyl in the backbone. The application of mixed chiral selectors led to improved separations, however; at most eleven PCB congeners were separated on a single column. Chiral resolution of o,p´-DDD was achieved. The use of a dimethylsiloxane/silarylene copolymer as a matrix for the cyclodextrins is a promising approach. With such a matrix, blocking of the CD cavities by silicone substituent groups can be avoided, and a reasonable CD solubility can be provided. The selectivity of heptakis(2,3-di-O-ethyl-6-O-tert-hexyldimethylsilyl)-β-CD and heptakis(2,3-di-O-methyl-6-O-tert-hexyldimethylsilyl)-β-CD was quite different, the former selector could separate four congeners, while the latter separated ten congeners.
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  • 49
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; UV detection ; organic acids ; background electrolyte optimization ; wine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A simple technique is described for the routine capillary electrophoretic determination of organic acids in wine samples. Several aromatic and non-aromatic compounds, including phthalic acid, benzoic acid, sorbic acid, boric acid, and phosphate, were evaluated as background electrolytes in order to obtain the highest resolution and detection sensivity. Factors that affect capillary electrophoretic separation such as the concentration and pH of the background electrolyte (BGE), the concentration of the electroosmotic flow modifier (EOF), and methanol addition to the electrolyte were investigated systematically. Tartaric, malic, succinic, acetic, and lactic acids were determined simultaneously in approximately six minutes using an electrolyte containing 3 mM phosphate and 0.5 mM myristyltrimethylammonium bromide (MTAB) as electroosmotic flow modifier at pH 6.5. This method is quantitative, with recoveries in the 90-102% range and linear up to 50 mg L-1. The precision is better than 1% and the procedure shows the appropriate sensibility, with detection limits between 0.015 and 0.054 mg L-1. The proposed method was successfully employed for the determination of organic acids in wine samples by direct sample injection after appropriate dilution and filtration.
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  • 50
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    Journal of High Resolution Chromatography 23 (2000), S. 688-692 
    ISSN: 0935-6304
    Keywords: Solid oxygen scavenger ; carrier gas purity ; manganous oxide ; glass press-fit connections ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 51
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    Journal of High Resolution Chromatography 23 (2000), S. 576-582 
    ISSN: 0935-6304
    Keywords: Gas chromatography-mass spectrometry ; amino acid enantiomers ; D-amino acids ; physiological fluids ; mammals ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Quantities of D-amino acids were determined in body fluids (urine, blood plasma and blood serum, milk) of mammals (hamster, horse, bovine, sheep, pig, and dog). Amino acids were isolated using a cation exchanger and converted into their N(O)-pentafluoropropionyl (or trifluoroacetyl) amino acid 2-propyl esters. Enantiomers were separated and quantified on a Chirasil-L-Val capillary column with mass spectrometric detection using selected ion monitoring. D-Enantiomers of most protein L-amino acids were detected. Largest absolute and relative amounts in most cases were determined for D-Ser and D-Ala in urine. Stereoisomers of 2,6-diaminopimelic acid were also measured in bovine, ovine, and porcine urine. Since D-amino acids were detected in all representative classes of the major orders of Mammalia, namely Artiodactyla, Perissodactyla, Rodentia, and Carnivora, and taking reports in the literature into account, it is postulated that D-amino acids occur in all mammals.
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  • 52
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    Journal of High Resolution Chromatography 23 (2000), S. 595-599 
    ISSN: 0935-6304
    Keywords: GC-MS/MS ; PCDDs ; PCDFs ; human tissue ; fish tissue ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This paper outlines the possibilities of selectivity and sensitivity enhancement in measuring PCDD/F congeners using an ion trap GC-MS/MS. The pressure of the collision gas and the collision energy were optimized. The modified GC-MS/MS method was applied to the determination of PCDDs and PCDFs in human and fish tissues. Limits of quantification were about 1 pg/g of fat for all seventeen 2378 PCDD/Fs tested (starting amount of fat, 2 g).
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  • 53
    ISSN: 0935-6304
    Keywords: On-line coupling HPLC/NMR ; HPLC/ESI-MS ; (2E,4Z)-decadienoic acid ; Agromyces spec ; isolation ; structure elucidation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 54
    ISSN: 0935-6304
    Keywords: High-performance liquid chromatography ; β-methyl amino acids ; enantioseparation ; quinine-derived chiral stationary phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quinine-derived chiral anion-exchange stationary phase was used for the direct high-performance liquid chromatographic separation of the enantiomers of the N-protected unusual β-substituted α-amino acids, β-methylphenylalanine, β-methyltyrosine, β-methyltryptophan, and β-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. The readily prepared 2,4-dinitrophenyl and tert-butyloxycarbonyl derivatives were well separated, and in most cases the separation of all four stereoisomers of these β-methyl-α-amino acids could be obtained in one chromatographic run. The elution sequences of the enantiomers of the different derivatives were determined and revealed a dependence on the type of the N-protecting group. In this context, the effects of different protecting groups (acetyl, tert-butyloxycarbonyl, benzoyl, 3,5-dinitrobenzoyl, benzyloxycarbonyl, 3,5-dinitrobenzyloxycarbonyl, 2,4-dinitrophenyl, and 9-fluorenylmethoxycarbonyl) on the chromatographic behavior were investigated.
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  • 55
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    Journal of High Resolution Chromatography 23 (2000), S. 637-643 
    ISSN: 0935-6304
    Keywords: HPLC ; fast separation ; flavan-3-ol ; flavonols ; vegetables ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A fast high-performance liquid chromatography method was used for analysis of prominent flavan-3-ols and flavonols in vegetables. Gradient elution with phosphoric acid-acetonitrile mixtures and phosphoric acid-methanol mixtures allowed fast and complete separation of the studied phenolic compounds within analysis times less than 10 min. The development of two elution gradients using methanol and acetonitrile as modifiers proved to be an excellent approach for the verification of the real polyphenolic composition in vegetables samples because the two optimized methods allowed the separation of the same number of compounds in the same elution order. Diode-array detection was employed for the provisional identification of phenolic compounds that were not available as standards. We preferred methanol as a modifier because it was less toxic and cheaper than acetonitrile. Detection limits ranged between 0.12 and 0.59 μg mL-1. High recoveries of phenolics from fresh vegetables were measured in all studied cases, independent of the phenolic structure, matrix, and vegetable in question. High levels of procyanidins between 150 and 450 mg kg-1 were found in all studied vegetables. Quantification of quercetin and kaempferol glycosides was only possible in marrow and onion, respectively.
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  • 56
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    Journal of High Resolution Chromatography 23 (2000), S. 656-658 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis (CE) ; laser induced fluorescence detection (LIFD) ; fluorescein isothiocyanate (FITC) ; inulin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 57
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    Journal of High Resolution Chromatography 23 (2000), S. 519-521 
    ISSN: 0935-6304
    Keywords: Scoparone ; phytoalexin ; citrus ; MEKC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new MEKC method has been developed to determine the amount of the phytoalexin, scoparone, in Citrus roots. The separation and analysis was achieved with a running buffer of 100 mM SDS, 25 mM phosphate and 12% (v/v) methanol pH 6.2. Separation was performed at 12 kV with 25°C and UV detection at 200 nm. A near complete recovery of scoparone was obtained with the extraction procedure. The MEKC method was compared with a fluorescence TLC method. The detection limit for scoparone with the MEKC method (2 μg/mL) was better than the TLC method (10 μg/mL).
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  • 58
    ISSN: 0935-6304
    Keywords: Capillary HPLC ; gradient elution ; temperature programming ; phenolic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This paper describes a liquid chromatographic method using a reversed phase capillary column coupled to an UV detector for the quantitation of thirteen pollutant phenols. Chromatographic separation was carried out with gradient elution at 25.0 ± 0.1°C. The two major anisocratic elution modes (gradient elution and temperature programming) were evaluated. The detection limit range was 10-81 pg (100 nL injected). The chromatographic method combined with liquid-liquid extraction was applied to analysis of these compounds in river water. Recoveries of 75-103% were achieved for most of them.
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  • 59
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    Journal of High Resolution Chromatography 23 (2000), S. 324-328 
    ISSN: 0935-6304
    Keywords: Antioxidants ; propyl gallate ; octyl gallate ; dodecyl gallate ; butylated hydroxyanisole ; butylated hydroxytoluene ; reverse-phase liquid chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The influence of cationic and anionic surfactants and short-chain alcohols in the mobile phase on the retention of five antioxidants has been studied. The solutes chosen were butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and propyl, octyl, and dodecyl gallates (PG, OG, DG).The surfactants were hexadecyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), and n-propanol (PrOH) was the selected alcohol. A simple isocratic reversed-phase method for the antioxidant determination is proposed. Separation of five primary antioxidants takes 18 min with the mobile phase SDS 0.10 M/H3PO4 0.01 M/PrOH 30%. Variation of the percentage of alcohol in the mobile phase permits optimization of the retention times of the antioxidants. Detection limits in the pg range were obtained for the all solutes. The method was used to determine the antioxidants in olive oil at three different levels, giving mean recoveries close to 100% for all the solutes (BHA 102%, PG 99%, OG 99%, DG 99%) except BHT (84%).
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  • 60
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    Journal of High Resolution Chromatography 23 (2000), S. 338-342 
    ISSN: 0935-6304
    Keywords: Polyunsaturated fatty acids (PUFA) ; high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS with APCI) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of polyunsaturated fatty acids using high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry is described. The standard fatty acid methyl esters from 16 to 22 carbons were analyzed by LC-MS with APCI. The effect of orifice voltage and total carbon atoms versus number of double bonds in each homologue on the mass spectra is discussed. The correction coefficients for homologues from saturated fatty acids to hexaenoic acid are also mentioned.
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  • 61
    ISSN: 0935-6304
    Keywords: 2H/1H ratio analysis ; HRGC-P-IRMS ; stable isotopes ; benzaldehyde ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Isotope ratio monitoring gas chromatography-mass spectrometry of the 2H/1H ratio by pyrolysis isotope ratio mass spectrometry (P-IRMS) was used to analyze benzaldehyde originating from various sources. Based on the δ2HSMOW value of an authentic reference sample determined with an elemental analyzer (EA), the range of reproducibility and linearity was checked. Correct (EA related) and reproducible data were obtained for sample amounts 〉0.6 μg benzaldehyde (on column). In another series of experiments, the influence of sample preparation, i. e. simultaneous distillation-extraction (SDE) was found to be negligible. The following ranges of δ2HSMOW values were determined for benzaldehyde using five types of samples, i. e. (i) synthetic (δ2HSMOW -78 to -85‰, ex benzal chloride; +420 to +668‰, ex toluene) and ‘natural’ (including ‘ex-cassia’) references (δ2HSMOW -83 to -144‰); (ii) bitter almond oils (δ2HSMOW -113 to -148‰); (iii) fruits (δ2HSMOW -111 to -146‰); (iv) kernels (δ2HSMOW -115 to -188‰); and (v) leaves (δ2HSMOW -165 to -189‰).
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  • 62
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    Journal of High Resolution Chromatography 23 (2000), S. 373-378 
    ISSN: 0935-6304
    Keywords: Open tubular columns ; capillary electrochromatography ; column efficiency ; injected volume ; applied voltage ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of some instrumental parameters on column efficiency in open tubular capillary electrochromatography (OTCEC) has been evaluated. First, it was investigated whether band broadening due to the sample injection process is within a tolerable range when an open tubular column (OTC) of about 10 μm i. d. is used. As a result of the small injection profile factor (K2 = 1.3), injected volumes must be sufficiently small (less than 10 pL) to avoid a significant efficiency loss (〉5%) when hydrodynamic injection by siphoning is employed. Secondly, the kinetic performance of OTCs in a CEC system was estimated from the variation of the reduced plate height (h) with the reduced linear velocity (ν) which was controlled by the voltage applied. Reasonable agreement was obtained between the theoretical h versus ν curve and the experimental values for a group of polycyclic aromatic hydrocarbons used as test compounds. Values of 0.25 for minimum h at an optimum ν of 16 are estimated, which permit separations with around 400,000 plates per meter to be obtained in less than 5 min. Finally, the possibility of estimating the diffusion coefficients of the solutes in the mobile phase from the plot of the height of a theoretical plate versus electroosmotic flow velocity is shown.
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  • 63
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    Journal of High Resolution Chromatography 23 (2000), S. 389-392 
    ISSN: 0935-6304
    Keywords: Capillary SFC ; zinc dialkyldithiophosphates ; lubricating oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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  • 64
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    Journal of High Resolution Chromatography 23 (2000), S. 393-396 
    ISSN: 0935-6304
    Keywords: Supercritical fluid chromatography (SFC) ; micropacked capillary columns ; waxes ; restoring ; objects of art ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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    Journal of High Resolution Chromatography 23 (2000), S. 379-385 
    ISSN: 0935-6304
    Keywords: Aroma ; “lulo del Chocó” ; Solanum topiro ; volatiles ; glycosidically bound volatiles ; glycoside TFA derivatives ; enantioselective gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The volatile constituents of lulo del Chocó (Solanum topiro) fruit pulp obtained by liquid-liquid extraction were analyzed by capillary GC and capillary GC-MS. In total, 30 components were identified with methyl salicylate, hexadecanoic acid, hexanal, guaiacol, ethyl butanoate, and ethyl acetate being the major components. Chirospecific MDGC analysis revealed the predominance of (R)-ethyl-3-hydroxybutanoate (ee 40%) and the presence of racemic mixtures both of δ-octalactone and of δ-decalactone. For γ-hexalactone, γ-octalactone, and γ-decalactone enantiomeric distributions of 22.4 : 77.6, 22.9 : 77.1, and 20.0 : 80.0, (R) : (S), respectively, were determined. Glycosidically bound aroma compounds were identified by capillary GC and capillary GC-MS after isolation of the glycosidic fraction obtained by Amberlite XAD-2 adsorption and methanol elution followed by hydrolysis with a commercial pectinase enzyme. In total 13 bound aroma compounds (aglycones) were identified. These aglycones mainly consisted of compounds exhibiting aromatic structures. Additionally, with the aid of capillary GC and capillary GC-MS (EI and NCI) of trifluoroacetylated derivatives we identified eight glucosides: the novel 3,6-epoxy-7-megastigmen-5,9-diol β-D-glucopyranoside and the hexyl, benzyl, linalyl oxide (furanic), 2-phenylethyl, vomifolyl (isomer 1), (6S,9R)-vomifolyl, and scopoletin β-D-glucopyranosides.
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  • 66
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    Journal of High Resolution Chromatography 23 (2000), S. 409-412 
    ISSN: 0935-6304
    Keywords: Cyclodextrin ; capillary electrophoresis ; system peak ; CHES 1 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a running buffer containing cyclodextrins (CDs) and 2-[N-cyclohexylamino]-ethanesulfonic acid (CHES), positive system peaks were observed in the analysis of a ganglioside mixture by CE-UV. These system peaks were related to CDs in the running buffer because these peaks were also detected when a plug of solution devoid of CDs but having the same CHES concentration and pH as the running buffer was injected. Neutral CDs were separated owing to the formation of inclusion complexes with the anionic CHES ion. One possible explanation for the positive system peaks is that the anionic CD-CHES inclusion complex is displaced by co-ions with higher UV absorptivity.
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  • 67
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    Journal of High Resolution Chromatography 23 (2000), S. 27-38 
    ISSN: 0935-6304
    Keywords: Monolith ; continuous bed column ; convective interaction media ; membrane chromatography ; membrane adsorber ; HPMDC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monolithic stationary phases have revolutionized protein chromatography because they combine speed, capacity, and resolution in a unique manner. Since such stationary phases contain no particles but only flow-through pores, the usual mass transfer restrictions to the chromatography of large molecules are not observed and extremely fast separations become possible. Recently the area of application of monolith chromatography has been extended to the separation and analysis of small molecules and plasmid DNA. This review summarizes the state of art in high performance monolith and especially high performance monolithic disk chromatography (HPMDC). The current understanding of the theory of protein HPMDC is summarized, while an introduction to the evolving field of small molecule HPMDC is attempted. The basic differences between the monolithic disks and columns packed with conventional stationary phases (including perfusion and micropellicular particles) but also monolithic columns (porous rods) are outlined. Finally, the potential of HPMDC to analytical and preparative biochromatography is demonstrated by a discussion of recent applications of chromatographic disks for protein isolation and bioprocess analysis.
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  • 68
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    Journal of High Resolution Chromatography 23 (2000), S. 44-46 
    ISSN: 0935-6304
    Keywords: In situ molecular imprinting ; continuous polymer rod ; miniaturized column ; chiral recognition ; diastereoselectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Molecularly imprinted continuous polymer rods are prepared inside PEEK tubes of 1 mm i. d. by an in situ preparation technique; and chiral separations on such media have been demonstrated. The miniaturized column filled with (-)-cinchonidine-imprinted or (+)-cinchonine-imprinted polymer rods based on a copolymer of 2-(trifluoromethyl)acrylic acid and ethylene glycol dimethacrylate permitted diastereoseparation of (-)-cinchonidine and (+)-cinchonine; the template molecule is retained to a greater extent than the corresponding antipode. Increasing the amount of cyclohexanol in the polymerization mixture decreased the backpressure of the resultant rod and the addition of latex beads suspended in water to the prepolymerization mixture affected the selectivity and affinity of the imprinted polymer rods. The column length is adjusted easily by cutting, thus allowing easy control of retention behavior and analysis time.
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  • 69
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    Journal of High Resolution Chromatography 23 (2000), S. 59-66 
    ISSN: 0935-6304
    Keywords: Enantiomeric separation ; capillary electrochromatography ; positively charged polyacrylamide gel ; allyl carbamoylated β-cyclodextrin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The novel enantiomeric separation of acidic and neutral compounds by capillary electrochromatography with β-cyclodextrin-bonded positively charged polyacrylamide gels was examined. The columns used are capillaries filled with a positively charged polyacrylamide gel, a so-called monolithic stationary phase, to which allyl carbamoylated β-CD derivatives covalently bind. The capillary wall was activated first by bifunctional reagent to make the resulting gel bind covalently inside the fused-silica tubing. Enantiomeric separations of sixteen acidic and two neutral compounds were achieved using the above-mentioned columns and 200 mmol dm-3 Tris-300 mmol dm-3 boric acid buffer (pH 8.1) as a mobile phase. High efficiencies of up to 150 000 plates m-1 were obtained for dansyl-DL-amino acids. The within-run and between-run reproducibilities of retention time and separation factor were examined for three dansyl-DL-amino acids and warfarin. The relative standard deviations of the within-run and between-run reproducibilities of retention time were less than 1.2 and 1.3% over the six injections, respectively. Those of the separation factor were less than 0.3 and 0.2%, respectively. The gel-filled capillaries were stable for at least four months with intermittent use.
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  • 70
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; cyclodextrins ; heptakis(2,6-di-O-tert-butyldimethylsilyl)-β-cyclodextrin ; heptakis(2,6-di-O-tert-butyldimethylsilyl-3-O-methyl)-β-cyclodextrin ; heptakis(3,6-di-O-tert-butyldimethylsilyl-2-O-methyl)-β-cyclodextrin ; octakis(2,6-di-O-tert-butyldimethylsilyl-3-O-methyl)-γ-cyclodextrin ; thermodynamic parameters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Separation factors and thermodynamic data for the separation of various chiral analytes on different di-O-tert-butyldimethyl-silylated cyclodextrin derivatives are collected and described. Modifying the substitution pattern of the tert-butyldimethylsilyl group in position 2 and 3 or changing from β- to γ-cyclodextrin significantly affects the separation properties of the cyclodextrin derivatives.
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  • 71
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    Journal of High Resolution Chromatography 23 (2000), S. 583-589 
    ISSN: 0935-6304
    Keywords: Monofunctionalized cyclodextrins ; enantioselective capillary-HPLC ; immobilized chiral stationary phases ; separation of chiral drugs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Heptakis(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin was monofunctionalized by the regioselective introduction of exactly one ω-epoxyoctyl group at the primary site of the cyclodextrin. The site-specifically substituted cyclodextrin was immobilized to commercially available aminopropyl silica by nucleophilic opening of the epoxy function of the spacer substituent resulting in a lipophilic chiral stationary phase with broad applicability for enantiomer separations in capillary-HPLC under reversed-phase conditions.
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  • 72
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    Journal of High Resolution Chromatography 23 (2000), S. 600-602 
    ISSN: 0935-6304
    Keywords: HPLC separation ; lucidin ; Rubia tinctorum ; anthraquinones ; isocratic elution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---An HPLC method has been developed for the separation of anthraquinones with particular attention to the determination of lucidin in commercially available sources of Rubia tinctorum aglycones. Variations of chromatographic conditions have been studied in order to provide suitable resolution of anthraquinones under isocratic conditions on an end-capped RP C18-column.
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  • 73
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    Journal of High Resolution Chromatography 23 (2000), S. 644-646 
    ISSN: 0935-6304
    Keywords: Stir Bar Sorptive Extraction (SBSE) ; thermal desorption (TD) ; capillary GC-MS ; benzoic acid ; beverages ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Stir Bar Sorptive Extraction (SBSE), a recently introduced solventless extraction technique, was applied for the enrichment of benzoic acid in lemon flavored beverages. The stir bar is covered with 50 mg polydimethylsiloxane (PDMS) and the extraction mechanism is similar to that of solid phase micro extraction (SPME) but the enrichment factor is ca. 100 times higher. SBSE is followed by thermal desorption (TD)-capillary gas chromatography (CGC)-mass spectroscopy (MS). Calibration graphs for benzoic acid were linear from 1 to 1000 ppm for water and diluted soft drinks and the repeatability (n = 6) was less than 5% RSD.
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  • 74
    ISSN: 0935-6304
    Keywords: Packed capillary LC ; large volume injection ; temperature programming ; ceramides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 75
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    Journal of High Resolution Chromatography 23 (2000), S. 677-680 
    ISSN: 0935-6304
    Keywords: Capillary ; fast separations ; mass spectrometry ; vacuum ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---There is a constant drive to speed up GC separations. Shorter analysis times provide more analyses per day, which reduces cost. One approach is to reduce column length and column diameter and columns of 0.15 mm i.d. have indeed grown in popularity. However, the majority of applications are still done with 0.25 mm and 0.32 mm columns.
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  • 76
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    Journal of High Resolution Chromatography 23 (2000), S. 138-142 
    ISSN: 0935-6304
    Keywords: Capillary electrochromatography ; nucleosides ; short-end injection ; phenyl-bonded silica ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The influence of several experimental parameters (pH, ionic strength, organic modifier content of hydro-organic buffer) upon EOF, migration time, and retention factor has been studied in CEC with a phenyl-bonded silica column on a model mixture of five nucleosides. This paper illustrates the current interest in CEC as a method of resolving complex mixtures of neutral and ionic solutes and demonstrates the potential of the short-end injection method as a means of reducing analysis time.
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  • 77
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    Journal of High Resolution Chromatography 23 (2000), S. 143-148 
    ISSN: 0935-6304
    Keywords: Analysis of anthraquinones ; capillary electrophoresis ; high-performance liquid chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The separation and determination of twelve anthraquinones, viz. anthraquinone 1, chrysphanol 2, aloe-emodin 3, alizarin 4, anthraquinone-2-carboxylic acid 5, purpurin 6, sennoside B 7, sennoside A 8, emodin 9, quinalizarin 10, rhein 11, and anthraflavic acid 12, were achieved by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Detection at 260 nm with a buffer solution containing 30 mM sodium borate (adjusted to pH = 10.56 with 0.05N NaOH) and acetonitrile (9 : 1) in CE or with a linear gradient elution containing 20 mM KH2PO4 with 0.05% phosphoric acid (pH = 2.91) and methanol in HPLC was found to be the most suitable approach for this separation. Contents of six components (2, 3, 7, 8, 9, 11) in crude Rhei Rhizoma extract could easily be determined within 39 min by CE or 63 min by HPLC. The effects of buffers on this separation and the validation of the two methods were studied.
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  • 78
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    Journal of High Resolution Chromatography 23 (2000), S. 474-478 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Solid-phase extraction, on-line derivatization, and measurement by ion trap mass spectrometry (ITD-MS) were used to investigate the biological degradation of pharmaceutical residues (clofibric acid, ibuprofen, diclofenac). The results of the single steps of sample pretreatment and analytical determination are reported. MS/MS measurements were performed on an ITD-MS by selecting collision induced dissociation of the molecular ions (M+) as parent ions to defined daughter ions. A pilot sewage plant and biofilm reactors operating under oxic and anoxic conditions were run as model systems with synthetic sewage water containing 10 to 50 mg/L dissolved organic carbon (DOC) and pharmaceuticals in concentrations of 10 μg/L. Clofibric acid displayed its persistent character in all cases. The pilot sewage plant and the oxic biofilm reactor showed comparable results for diclofenac and ibuprofen, which both were partly degraded. These results can explain the occurrence of these substances in sewage effluents and in the aquatic environment. A high degree of degradation was found especially for ibuprofen in the oxic biofilm reactor, which was attributed to adaptation of the biofilm to the residue. Two metabolites of ibuprofen could be identified on the basis of their mass spectra and comparison with literature data, viz. hydroxyibuprofen and carboxyibuprofen.
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  • 79
    ISSN: 0935-6304
    Keywords: Silicone oil ; supercritical fluid chromatography (SFC) ; micropacked columns ; MALDI-TOF ; GC/MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 80
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    Journal of High Resolution Chromatography 23 (2000), S. 511-514 
    ISSN: 0935-6304
    Keywords: CZE ; indirect UV detection ; metal ions ; ecological samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 81
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    Journal of High Resolution Chromatography 23 (2000), S. 235-244 
    ISSN: 0935-6304
    Keywords: Comprehensive two-dimensional GC ; peak overlap ; statistical-overlap theory ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The need for two-dimensional gas chromatography is justified by the extent of peak overlap in one-dimensional gas chromatograms (GCs) of complex mixtures. Such overlap was predicted long ago by statistical-overlap theory (SOT). In this paper, SOT is conceptually reviewed and its predictions are shown to be quantitatively accurate. GCs of complex mixtures of polychlorinated biphenyls, pyridine- and nitrogen-containing polynuclear aromatic hydrocarbons, tetrachlorodibenzo-p-dioxins and dibenzofurans, fatty acid methyl esters, flavors and fragrances, and naphtha were simulated by commercial GC software on DB-1, DB-5, and Stabilwax stationary phases. The numbers of peak maxima in the GCs agreed with predictions of SOT, when the interval of time between successive peaks of pure compounds was described by Poisson statistics. This agreement was realized even though the time intervals actually are deterministic, not statistical. In addition, the numbers of mixture components were predicted with accuracy by regression of peak numbers against SOT. Similar regressions have been reported before, but the theory used here is more sophisticated and its predictions consequently are more accurate. Future directions for finalizing SOT are suggested.
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  • 82
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    Journal of High Resolution Chromatography 23 (2000), S. 304-308 
    ISSN: 0935-6304
    Keywords: Enantioselectivity ; gas chromatography ; ethylated γ-cyclodextrin ; toxaphene ; enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The enantioselectivity of three batches of octakis-(2,3,6-tri-O-ethyl)-γ-cyclodextrin (TEG-CD), which differed significantly in their degree of ethylation, is reported for toxaphene congeners. The cyclodextrin composition was determined by high performance liquid chromatography-mass spectrometry. Columns prepared with almost fully ethylated cyclodextrin showed no enantiomer separation. Increasing the average number of free OH groups up to an optimum of 3.8 allowed to resolve the following toxaphene congeners into enantiomers: Parlar no. 11, 12, 15, 21, 25, 32, 38, 42.1, 42.2, 50, 51, 56, 58, 59, 62, 69 as well as B8-1412. More free OH groups did not improve the enantiomer resolution. The structure of the polysiloxane used for dilution of TEG-CD also had an influence on the enantiomer separations achieved. Compared to OV 1701-OH, the use of PS 086 significantly improved the enantiomer resolutions of the separated congeners. However, neither increasing the column length nor the cyclodextrin amount in the stationary phase led to better separation results.
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  • 83
    ISSN: 0935-6304
    Keywords: HPLC ; industrial wastewater ; process development ; 4-amino-azobenzene-4′,5-disulfonic acid (AABDS) ; 4-amino-azobenzene (AAB) ; 4-amino-azobenzene-4′-sulfonic acid (AABS) ; 4-amino-azobenzene-4′,3,5-trisulfonic acid (AABTS) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A simple and rapid reversed-phase high-performance liquid chromatographic method for the separation and determination of 4-amino-azobenzene-4′,5-disulfonic acid (AABDS) and its process-related impurities was developed. The separation was achieved on a μ-Bondapak C18 column using 0.15 M ammonium sulfate-acetonitrile (55:45) (v/v) as eluent. A UV-visible spectrophotometric detector fixed at 386 nm was used both for detection and quantitation. The method was used not only for quality assurance but also for process development and wastewater management of AABDS.
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  • 84
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    Journal of High Resolution Chromatography 23 (2000), S. 317-323 
    ISSN: 0935-6304
    Keywords: Conjugated linoleic acids ; underivatized ; Ag+-HPLC ; resolution ; mixed mode retention ; hydrogen bonding ; competing acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Fatty acids (FAs) and fatty acid residues are generally methylated and analyzed by GC. The reasons for this are partly historic and partly because of the sensitivity advantage of flame ionization detection over UV absorption by the carboxylic acid functionality in saturated FAs. However, for strongly absorbing unsaturated acids such as the conjugated linoleic acids (CLAs), the sensitivity advantage is greatly reduced. Hence there seems little reason to waste time and introduce errors associated with methylation. Remarkably, this appears not to have been recognized. In this paper we describe our method development for the analysis of underivatized CLAs by silver ion HPLC separation on the ChromSpher Lipids column. Using mobile phases previously optimized for the analysis of the methylated CLAs, retention is excessive and a competing acid is required. Various combinations of small concentrations of acetic acid (3.0-2.5%) with acetonitrile (0.0-0.025%), respectively, yield similar resolution and run times. As well as its role as a competing acid, acetic acid acts as a general strong solvent and thus can be used alone as a modifier (without acetonitrile). However, for slightly shorter run times a mobile phase of 2.5% acetic acid and 0.025% acetonitrile was chosen as the optimum mobile phase for analysis. The separation of the free CLAs is clearly superior to those previously published and obtained in this study for the methylated CLAs. The additional specific strong interactions of the underivatized CLAs seem certain to be due to hydrogen bonding between the CLA carboxylic acid functionality and the large number of residual silanols on the surface of the silica support of the stationary phase.
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  • 85
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    Journal of High Resolution Chromatography 23 (2000), S. 333-337 
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; chiral separation ; chiral stationary phase ; separation of enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new reciprocal π-basic chiral stationary phase (CSP) was designed based on the reciprocity conception of chiral recognition and prepared starting from (S)-leucine. The CSP thus prepared was applied in resolving various π-acidic N-(3,5-dinitrobenzoyl)-α-amino amides and esters and found to be very effective. Especially, N-(3,5-dinitrobenzoyl)-α-amino N,N-dialkyl amides were resolved very well on the new reciprocal CSP. From the chromatographic resolution results and based on the reciprocity conception of chiral recognition with the aid of Corey/Pauling/Koltan (CPK) molecular model studies, a chiral recognition mechanism which utilizes π-π interaction and simultaneously two hydrogen bonding interactions between the CSP and the analyte has been proposed. The CSP prepared in this study was also successful in resolving 3,5-dinitrophenylcarbamate derivatives of 2-hydroxycarboxylic acid esters.
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  • 86
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    Journal of High Resolution Chromatography 23 (2000), S. 343-347 
    ISSN: 0935-6304
    Keywords: SPME ; desorption ; fiber conditioning ; field sampling ; sample preparation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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  • 87
    ISSN: 0935-6304
    Keywords: Silver ion high-performance liquid chromatography (Ag-HPLC) ; conjugated linoleic acid (CLA) ; p-methoxyphenacyl derivatives ; single-column Ag-HPLC ; fatty acid analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 88
    ISSN: 0935-6304
    Keywords: Retention factors ; styrene divinylbenzene polymer ; porous graphitic carbon ; solid-phase extraction ; water analysis ; polar organic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---LC retention data have been measured using various stationary phases with an emphasis on highly polar to moderately polar neutral organic compounds having octanol-water partition coefficients (Kow) in log units between 0 and 3. The relationships between the retention factor measured in water and the octanol-water partition coefficient are linear but with different slopes for octadecyl (C18) silicas, and two polystyrene divinylbenzene (PS-DVB) phases with low and high surface areas. These relationships confirm that highly cross-linked polymers can provide more than 1000-times higher retention values than C18 silicas for moderately polar analytes but close values for highly polar ones. They also explain why C18 silicas and polymers are equivalent for the separation of very polar analytes. In contrast, due to a different retention mechanism, no relation exists between the retention shown by porous graphitic carbons (PGC) and analyte hydrophobicity, but highly polar analytes are in general much more strongly retained than by any other sorbent. The potential of PGC for both the extraction and the separation of analytes is shown. Due to the difference in separation mechanism, PGC is the analytical phase that should be used for confirmation of the identity of analytes instead of a cyanopropylsilica column as recommended in some environmental procedures. Applications are presented for the trace-determination of triazines and polar degradation products in ground and surface water with detection limits below the 0.1 μg/L level.
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  • 89
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    Journal of High Resolution Chromatography 23 (2000), S. 449-454 
    ISSN: 0935-6304
    Keywords: Denuders ; isolation and enrichment ; analysis ; volatile organic compounds ; partition coefficients Kfs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The possibility of using a piece of gas chromatographic capillary column as a tubular denuder for isolation and enrichment of organic pollutants present in air was studied. The partition coefficients (Kfs) of typical organic pollutants (benzene, chlorobenzene, toluene) between the gaseous phase and the denuder sorption layer were determined and effects of analyte concentration in the gaseous phase and gas flow rate on partitioning were studied. The partition coefficients were found to be constant in the studied range of concentration and gaseous mixture flow rate. A piece of a capillary column coated with polydimethylosiloxane can be used as a tubular denuder.
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  • 90
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    Journal of High Resolution Chromatography 23 (2000), S. 539-546 
    ISSN: 0935-6304
    Keywords: Headspace sampling ; Headspace Sorptive Extraction (HSSE) ; SPME ; aromatic plants ; medicinal plants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new sampling technique, Headspace Sorptive Extraction (HSSE), is here applied for the first time to the headspace sampling of medicinal and aromatic plants. The analyte partition coefficient between HSSE-PDMS stir bar and sample headspace (K1), the concentration factor (CF), the reproducibility, and the minimum recoverable amount were determined by analyzing standard solution of high volatility C5-C7 compounds with different polarities and structures (cyclohexane, propyl acetate, hexanal, 1-hexen-3-ol, isoamyl acetate, and 2-heptanol). Four aromatic and medicinal plants, viz. rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), thyme (Thymus vulgaris L.), and valerian (Valeriana officinalis L.) were analyzed by HSSE-GC with PDMS stir bars, and their concentration capacity was compared with those of S-HS and HS-SPME with different fibers. HSSE showed very high concentration capability with both standard and real sample components.
    Additional Material: 3 Ill.
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  • 91
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 547-553 
    ISSN: 0935-6304
    Keywords: Capillary GC ; static and dynamic headspace sampling ; sorptive and adsorptive extraction ; plant volatiles ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Static and dynamic headspace sampling have been applied for the enrichment of volatiles emitted by living plants. For solid phase microextraction (SPME) the sorptive fibers polydimethylsiloxane (PDMS) and polyacrylate (PA) have been compared and, in accordance with the like-like principle, polar compounds exhibit more affinity for the PA fiber while apolar solutes favor the PDMS fiber. For dynamic sampling, tubes packed with PDMS particles show greater inertness than Tenax; some Tenax decomposition products, e.g. benzaldehyde and acetophenone, interfere with the analyses. With PDMS particles operated in the breakthrough mode, the obtained profiles are similar to those obtained by SPME on the PA fiber. Recoveries relative to a packed PDMS bed are 85% for Tenax, 2.4% for SPME-PDMS, and 6.2% for SPME-PA.
    Additional Material: 5 Ill.
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  • 92
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 561-564 
    ISSN: 0935-6304
    Keywords: Retention factors ; Cinnamomi ramulus ; high-performance liquid chromatography ; capillary electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 3 Ill.
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  • 93
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 590-594 
    ISSN: 0935-6304
    Keywords: Ion chromatography ; graphitic carbon stationary phases ; anions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Inorganic anions could be separated on porous graphitic carbon stationary phases in ion chromatography. Ion exchange between eluent anions and sample anions on the stationary phase was confirmed by the retention behavior and the possibility of indirect photometric detection. The elution order of anions was different from that observed for commercially available anion exchangers. Chloride, nitrate, and sulfate contained in tap water could be determined in 7 min.
    Additional Material: 6 Ill.
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  • 94
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 697-698 
    ISSN: 0935-6304
    Keywords: Gentiana rigescens Franch ; gentiopicroside ; swertiamarin ; MEKC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
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  • 95
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 479-484 
    ISSN: 0935-6304
    Keywords: Programmable temperature vaporizing injection (PTV) ; thermal desorption ; gas chromatography ; mass spectrometry ; plasticizers ; polyethylene ; food wrapping film ; explosive powders ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Programmable Temperature Vaporizing Injection (PTV) has been used extensively as a means of injecting large volumes of samples to enhance sensitivity. This paper describes the use of PTV injection in the desorption mode for the analysis of a range of solid samples, and four examples of this application are described in detail. Detection by mass spectrometry was used extensively as a means of identification of the components in the various samples which were characterized.
    Additional Material: 12 Ill.
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  • 96
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 497-501 
    ISSN: 0935-6304
    Keywords: Historical remarks ; modern separation methods ; gas chromatography ; selective sorbents ; selectors ; discovery process ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The research conducted and the discoveries during the development of chromatography are briefly surveyed, with emphasis being placed on gas chromatography. Some actors are presented who played major roles en route from Tswett's original discovery to modern separation methods. The article is based mainly on personal memories and encounters. A few examples of the participation of our country in the development of chromatography are mentioned as well as international contacts. Some remarks are made on the use of selective sorbents or selectors in modern analytical separations. The paper closes with a few comments on the “philosophy” of the discovery process.
    Additional Material: 1 Tab.
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  • 97
    ISSN: 0935-6304
    Keywords: Comprehensive two-dimensional GC ; time-of-flight ; oil analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In this work a comprehensive two-dimensional system (GC×GC) was coupled to a time-of-flight mass spectrometer (TOF/MS) for the analysis of oil samples. Group-types like the alkanes and saturated cyclic compounds (naphthenes), which are present in oil, are shown separately by selecting their unique masses. On selecting appropriate ion fragments, this method also permits the determination of sulfur- and oxygen-containing species in oil. Former results obtained by FID detection could be confirmed. After proper selection of unique ions in GC×GC-TOF both selectivity and sensitivity increase.
    Additional Material: 6 Ill.
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  • 98
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 515-518 
    ISSN: 0935-6304
    Keywords: Capillary supercritical fluid chromatography (c-SFC) ; coal analysis ; SFE ; instrumentation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This work describes the construction and evaluation of a simple and versatile capillary supercritical fluid chromatographic (SFC) system and its application to the analysis of liquid fuels obtained by SFE. The modular supercritical fluid chromatography (SFC) system uses a syringe pump, a fused silica capillary column (100 μm i.d., coated with a 0.2-μm thick film of 5% phenylpolymethylsiloxane), a FID detector, and a high pressure injection valve with a 60-nL internal loop. Coal-derived samples were obtained by supercritical fluid extraction (SFE) of a Brazilian high-inertinite coal from Amando Simões mine, located in Paraná state (Brazil) using toluene as solvent and operating in the static mode. SFE was followed by preparative liquid chromatography fractionation into eight discrete fractions (PLC-8 method). Two of those fractions (F-2 and F-8) were used to evaluate the proposed set-up. The system described proved to be simple, easy-to-use, and versatile when used in the analysis of a range of samples from low molecular weight-low volatility (F-2) to higher molecular weight-high polarity asphaltols (F-8).
    Additional Material: 3 Ill.
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  • 99
    ISSN: 0935-6304
    Keywords: Reversed-phase high performance liquid chromatography (RP-HPLC) ; relationships between retention and eluent composition ; linear and quadratic models ; statistical comparison of ; evaluation of HPLC columns ; stationary phases ; lipophilicity/hydrophobicity ; log kw ; log P ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Statistical evaluation of linear and quadratic models of chromatographic retention was performed. The relationships describing retention were derived for a set of 23 carefully selected test analytes chromatographed on 18 HPLC columns using methanol-water or acetonitrile-water solutions as mobile phase. It was ascertained whether the square term in the quadratic model improves the description of chromatographic retention in a statistically significant manner. It was also checked whether the retention data extrapolated to a hypothetical neat water eluent (log kw) obtained with the two models and the two organic modifiers are equivalent or should be considered different. The research proved that both models yield similar results and the extrapolated log kw values do not differ statistically significantly in the case of methanol-containing mobile phases. In the case of acetonitrile-water systems the log kw values obtained with linear and quadratic models are normally statistically different. Correlation analysis for log kw vs. log P parameters was performed for data determined on six columns. The best correlations were achieved employing log kw data derived with the linear model for methanol/water systems.
    Additional Material: 3 Ill.
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  • 100
    ISSN: 0935-6304
    Keywords: High performance size exclusion chromatography ; molecular weight ; lignin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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