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  • 1
    Electronic Resource
    Electronic Resource
    Thrombin uptake and inhibition on endothelium and surfaces with a stable heparin coating: A comparative in vitro study (1986)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 235-246 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The endothelial lining and two differently heparin-coated surfaces were compared in vitro regarding thrombin uptake and inhibition. One heparin surface was based on stabilized ionic binding of heparin, the other on covalent binding of partially degraded heparin. Both heparin surfaces have previously been shown to have pronounced thromboresistant properties. The two heparinized polyethylene surfaces and the endothelial surface of segments of the porcine aorta were studied. After exposure to the surfaces, thrombin disappeared from the solution and appeared bound to the surfaces. The disappearance rate of thrombin from the solution was the same on exposure to the endothelium and the covalently bonded heparin surface, but less following exposure to the ionically bonded heparin surface. The thrombin activity appearing on the endothelium was lower than on the heparin surfaces, indicating that the endothelium exerted a slow thrombin inhibiting capacity. On exposure of the thrombin-loaded endothelium to plasma, thrombin was rapidly inhibited. Thrombin bound to the covalently bonded heparin surface was inhibited at a slower rate than on the ionically bonded surface, but still faster than the rate at which free thrombin was inhibited in nonheparinized plasma. It is concluded that the endothelium and stabilized heparin coatings bind thrombin and accelerate its inhibition by plasma.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820200212
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  • 2
    Electronic Resource
    Electronic Resource
    R studies of coordinatively unsaturated surface compounds on silica gel. II. CO complexes of nickel(II) (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 453 (1979), S. 139-152 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: IR-Untersuchungen an koordinativ ungesättigten Oberflächenverbindungen auf Kieselgel. I. CO-Komplexe mit Nickel(II)Die IR-Spektren der im Titel genannten Verbindungen zeigen eine Absorptionsbande, verursacht durch die Valenzschwingung adsorbierten CO's (2198,5 cm-1) bei Raumtemperatur und geringem CO Druck (20 Torr) und drei Banden (2180, 2195 und 2 206 cm-1) bei tiefen Temperaturen (-70 bis -145°C). Die zuerst genannte Bande wird einem trans quadratisch-planaren Komplex mit zwei CO-Molekülen zugeordnet und die anderen drei einem oktaedrischen Komplex mit vier CO-Molekülen. Durch Verwendung geänderter Darstellungsbedingungen konnte auch ein cis quadratisch-planarer Komplex mit zwei CO-Molekülen erhalten werden (2184,5 und 2194 cm-1). Die Reduktion der im Titel genannten Verbindungen mit CO bei Raum- oder niedrigeren Temperaturen zu Nickel(I) und Nickel(0) wurde untersucht, und ein Reaktionsmechanismus wird hierfür vorgeschlagen. Beide Reaktionen (die Umwandlung in einen cis Oberflächenkomplex und die Reduktion) werden auf der Grundlage einer CO-Einschiebung in eine Ni(II)—O-Bindung erklärt, wobei eine relativ instabile Nickel(I)-Verbindung gebildet wird (-Schwingung bei 1758 (1804) cm-1).
    Notes: The IR spectra of the title compounds show one absorption band due to the stretching vibration of adsorbed CO (2198.5 cm-1) at room temperature and low CO pressure (20 Torr CO) and three bands (2180, 2 195 and 2206 cm-1) at low temperatures (-70 to -145°C). The first band is assigned to a trans square-planar complex with two CO molecules and the latter to an octahedral complex with four CO molecules. Using a different preparation method it was possible to obtain also a cis square-planar complex with two CO molecules (2 181.5 and 2194 cm-1). The reduction of the title compounds to nickel(I) and nickel(0) with CO at room or low temperatures was investigated and a reaction mechanism is proposed. Both reactions (conversion to a cis surface complex and the reduction) are explained on the basis of a CO insertion into a Ni(II)—O- bond, by which a relatively unstable nickel(I) compound is produced ( vibration at 1 758 (1 804) cm-1).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794530617
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  • 3
    Electronic Resource
    Electronic Resource
    IR Studies of Coordinatively Unsaturated Surface Compounds on Silica Gel. IV. CO Complexes of Chromium(II) and Chromium(III) (1981)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 478 (1981), S. 119-138 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: IR-Untersuchungen an koordinativ ungesättigten Oberflächenverbindungen auf Kieselgel. IV. CO-Komplexe mit Chrom(II) und Chrom(III)Drei verschiedene Chrom(II)-Oberflächenverbindungen konnten anhand der IR-Spektren von adsorbiertem CO ermittelt werden. Besonders wichtig für die Erklärung der Untersuchungen sind die Absorptionsbanden zwischen 2050 und 2035 cm-1 und die relativen Intensitäten der CO-Banden bei 2100 und 2120 cm-1. Die Banden zwischen 2192 und 2179 cm-1 zeigen ebenfalls unterschiedliches Verhalten mit jeder der drei Chrom(II)-Oberflächenverbindungen. Zwei Chrom(III)-Oberflächenverbindungen konnten durch das Auftreten entweder einer CO-Bande bei 2200 cm-1 oder von zwei Banden bei 2206 und 2196 cm-1 nachgewiesen werden. Drei Modelle werden für die im Titel genannten Chrom(II)-Verbindungen vorgeschlagen, die alle auf zweikernigen Oberflächenkomplexen beruhen: Modell eins und zwei enthalten Chrom(II)-Ionen mit trans- und cis-Konfiguration in unterschiedlichen Kombinationen und das dritte Modell enthält ein Brückensauerstoffion von einer Siloxangruppe als störenden Liganden. Die drei Modelle erklären die CO-Banden ausreichend und ein Modellvorschlag stimmt nahezu quantitativ mit früheren volumetrischen Adsorptionsmessungen überein, die den überraschenden Effekt einer mit abnehmender Temperatur ebenfalls abnehmenden CO-Adsorption zeigten. Zwei Modelle mit entweder einer Sauerstoff-Doppelbrücke oder nur einer Sauerstoffbrücke werden für die beiden Chrom(III)-Oberflächenverbindungen vorgeschlagen.
    Notes: Three different chromium(II) surface compounds have been identified by their IR spectra of adsorbed CO. Especially important in the interpretation of the experiments are the bands between 2050 and 2035 cm-1 and the relative intensities of the CO bands at 2100 and 2120 cm-1. The bands between 2192 and 2179 cm-1 show also a different pattern for each of the different chromium(II) surface compounds. Two chromium(III) surface compounds could be identified by the presence of either one CO band near 2200 cm-1 or two bands near 2206 and 2196 cm-1. Three models are proposed for the chromium(II) title compounds, all related to dinuclear chromium(II) surface complexes: Models one and two have chromium(II) ions with trans and cis configuration in different combinations, respectively, and the third model has a bridging oxygen ion from a siloxan group as a distorting ligand. The three models explain the CO absorptions sufficiently and one is nearly quantitatively in agreement with previous volumetric adsorption studies of CO on chromium(II), which showed the surprising effect of decreasing CO adsorption with decreasing temperature. Two models for the chromium(III) surface compounds are proposed with either an oxygen double bridge or only one bridging oxygen.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19814780714
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  • 4
    Electronic Resource
    Electronic Resource
    IR studies of coordinatively unsaturated surface compounds on silica gel. I. CO complexes of manganese(II), iron(II), and cobalt(II) (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 453 (1979), S. 127-138 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: IR-Untersuchungen an koordinativ ungesättigten Oberflächenverbindungen auf Kieselgel. I. CO-Komplexe mit Mangan(II), Eisen(II) und Kobalt(II)Unter Anwendung von zwei verschiedenen Darstellungsmethoden (Ausheizen im Vakuum bei 900°C unter einem Druck von kleiner als 5 · 10-3 und größer als 10-2 Torr) für die im Titel genannten Oberflächenverbindungen konnten mehrere CO Komplexe untersucht werden. Die IR-Banden der Komplexe mit zwei CO Molekülen werden anhand der bekannten Zuordnung der IR-Spektren von Carbonylen als tetraedrisch (Mangan(II)), cis quadratisch-planar (Kobalt(II)) und trans quadratisch-planar (Eisen(II), Kobalt(II)) interpretiert. Die bekannten IR-Spektren von ähnlichen Chrom(II)-CO-Oberflächenverbindungen werden ebenso anhand cis und trans quadratisch-planarer Komplexe gedeutet.
    Notes: Using two different methods of preparation (vacuum heat treatment at 900°C with a pressure below 5 · 10-3 and higher than 10-2 Torr) of the title surface compounds made it possible to investigate several of their CO complexes. The IR bands of the complexes with two CO molecules are interpreted on the basis of the proven assignments of IR spectra of carbonyls as tetrahedral (manganese(II)), cis square-planar (cobalt(II)) and trans square-planar (iron(II), cobalt(II)). The known IR spectra of similar chromium(II) CO surface compounds are explained in the same way on the basis of cis and trans square-planar complexes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794530616
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  • 5
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    Zeeman effect in atmospheric O2 measured by ground-based microwave radiometry (2015)
    Copernicus
    Details
    Publication Date: 2015-04-23
    Description: In this work we study the Zeeman effect on stratospheric O2 using ground-based microwave radiometer measurements. The interaction of the Earth magnetic field with the oxygen dipole leads to a splitting of O2 energy states, which polarizes the emission spectra. A special campaign was carried out in order to measure this effect in the oxygen emission line centered at 53.07 GHz. Both a fixed and a rotating mirror were incorporated into the TEMPERA (TEMPERature RAdiometer) in order to be able to measure under different observational angles. This new configuration allowed us to change the angle between the observational path and the Earth magnetic field direction. Moreover, a high-resolution spectrometer (1 kHz) was used in order to measure for the first time the polarization state of the radiation due to the Zeeman effect in the main isotopologue of oxygen from ground-based microwave measurements. The measured spectra showed a clear polarized signature when the observational angles were changed, evidencing the Zeeman effect in the oxygen molecule. In addition, simulations carried out with the Atmospheric Radiative Transfer Simulator (ARTS) allowed us to verify the microwave measurements showing a very good agreement between model and measurements. The results suggest some interesting new aspects for research of the upper atmosphere.
    Print ISSN: 1867-1381
    Electronic ISSN: 1867-8548
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
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    O+ transport in the dayside magnetosheath and its dependence on the IMF direction (2015)
    Copernicus
    Details
    Publication Date: 2015-03-09
    Description: Recent studies have shown that the escape of oxygen ions (O+) into the magnetosheath along open magnetic field lines from the terrestrial cusp and mantle is significant. We present a study of how O+ transport in the dayside magnetosheath depends on the interplanetary magnetic field (IMF) direction. There are clear asymmetries in the O+ flows for southward and northward IMF. The asymmetries can be understood in terms of the different magnetic topologies that arise due to differences in the location of the reconnection site, which depends on the IMF direction. During southward IMF, most of the observed magnetosheath O+ is transported downstream. In contrast, for northward IMF we observe O+ flowing both downstream and equatorward towards the opposite hemisphere. We observe evidence of dual-lobe reconnection occasionally taking place during strong northward IMF conditions, a mechanism that may trap O+ and bring it back into the magnetosphere. Its effect on the overall escape is however small: we estimate the upper limit of trapped O+ to be 5%, a small number considering that ion flux calculations are rough estimates. The total O+ escape flux is higher by about a factor of 2 during times of southward IMF, in agreement with earlier studies of O+ cusp outflow.
    Print ISSN: 0992-7689
    Electronic ISSN: 1432-0576
    Topics: Geosciences , Physics
    Published by Copernicus on behalf of European Geosciences Union.
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  • 7
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    Zeeman effect in atmospheric O2 measured by ground-based microwave radiometry (2015)
    Copernicus
    Details
    Publication Date: 2015-01-05
    Description: In this work we study the Zeeman effect on stratospheric O2 using ground-based microwave radiometer measurements. The interaction of the Earth magnetic field with the oxygen dipole leads to a splitting of O2 energy states which polarizes the emission spectra. A special campaign was carried out in order to measure this effect in the oxygen emission line centered at 53.07 GHz. Both a fixed and a rotating mirror were incorporated to the TEMPERA (TEMPERature RAdiometer) radiometer in order to be able to measure under different observational angles. This new configuration allowed us to change the angle between the observational path and the Earth magnetic field direction. Moreover, a high resolution spectrometer (1 kHz) was used in order to measure for the first time the Zeeman effect in the main isotopologue of oxygen from ground-based microwave measurements. The measured spectra showed a clear polarized signature when the observational angles were changed evidencing the Zeeman effect in the oxygen molecule. In addition, simulations carried out with the Atmospheric Radiative Transfer Simulator (ARTS) allowed us to verify the microwave measurements showing a very good agreement between model and measurements. The results suggest some interesting new aspects for research of the upper atmosphere.
    Electronic ISSN: 1867-8610
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 8
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    Modeling the Zeeman effect in high altitude SSMIS channels for numerical weather prediction profiles: comparing a fast model and a line-by-line model (2015)
    Copernicus
    Details
    Publication Date: 2015-10-02
    Description: We present a comparison of a reference and a fast radiative transfer model using numerical weather prediction profiles for the Zeeman-affected high altitude Special Sensor Microwave Imager/Sounder channels 19–22. We find that the models agree well for channels 21 and 22 compared to the channels' system noise temperatures (1.9 and 1.3 K, respectively) and the expected profile errors at the affected altitudes (estimated to be around 5 K). For channel 22 there is a 0.5 K average difference between the models, with a standard deviation of 0.24 K for the full set of atmospheric profiles. Same channel, there is 1.2 K in average between the fast model and the sensor measurement, with 1.4 K standard deviation. For channel 21 there is a 0.9 K average difference between the models, with a standard deviation of 0.56 K. Same channel, there is 1.3 K in average between the fast model and the sensor measurement, with 2.4 K standard deviation. We consider the relatively small model differences as a validation of the fast Zeeman effect scheme for these channels. Both channels 19 and 20 have smaller average differences between the models (at below 0.2 K) and smaller standard deviations (at below 0.4 K) when both models use a two-dimensional magnetic field profile. However, when the reference model is switched to using a full three-dimensional magnetic field profile, the standard deviation to the fast model is increased to almost 2 K due to viewing geometry dependencies causing up to ± 7 K differences near the equator. The average differences between the two models remain small despite changing magnetic field configurations. We are unable to compare channels 19 and 20 to sensor measurements due to limited altitude range of the numerical weather prediction profiles. We recommended that numerical weather prediction software using the fast model takes the available fast Zeeman scheme into account for data assimilation of the affected sensor channels to better constrain the upper atmospheric temperatures.
    Electronic ISSN: 1867-8610
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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