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  • 1
    Publication Date: 2003-01-01
    Print ISSN: 0009-5893
    Electronic ISSN: 1612-1112
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 2
    Publication Date: 1982-01-01
    Print ISSN: 0340-6717
    Electronic ISSN: 1432-1203
    Topics: Biology , Medicine
    Published by Springer
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  • 3
    Publication Date: 1957-01-01
    Print ISSN: 0028-1042
    Electronic ISSN: 1432-1904
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Published by Springer
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  • 4
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Summary An orifice viscosimeter with automatic measuring device is constructed in which extensional flow is realized in good approximation. With this, together with appropriate rotational viscometers, measurements on concentrated suspensions of rigid spheres in Newtonian liquids are performed. Significant differences are found between viscosities in orifice and shear flows. In extensional flow suspensions of monodisperse glass-spheres with a medium concentration range (0.2 〈Φ 〈 0.52) show lower viscosities than in shear flow, whereas with the highest concentrations (Φ 〉 0.52) extensional viscosities become higher than shear viscosities. These results can be explained by different mechanisms of configurational rearranging of the spheres. In shear flows at very high concentrations transition from viscous to granular flow is observed. Under these conditions monodisperse spheres arrange into hexagonally packed layers which are sliding one upon another. Even a more pronounced effect of flow type is observed when PMMA spheres in oil are used. Now in shear flow shear-thinning occurs, whereas in extensional flow the same as before a constant viscosity is measured of which the value corresponds to the upper Newtonian shear viscosity. This may be explained by the greater effectivity of extensional flow with respect to desagglomeration processes. When in suspensions of glass spheres oil as the suspending medium is substituted by an aqueous solution of glucose higher values of relative viscosities are realized. There are some indications that this is effected by repulsive mutual forces.
    Notes: Zusammenfassung Es wird ein Auslaufviskosimeter mit automatischer Meßwertermittlung konstruiert, in dem in guter Näherung eine Dehnströmung realisiert ist. Hiermit werden in Verbindung mit geeigneten Rotationsviskosimetern vergleichende Messungen an konzentrierten Suspensionen von starren Kugeln in newtonschen Flüssigkeiten durchgeführt, wobei ausgeprägte Unterschiede auftreten. So ergeben sich bei Suspensionen von monodispersen Glaskugeln in Öl in der Dehnströmung für mittlere Konzentrationen (0,2 〈Φ 〈 0,52) deutlich kleinere, für hohe Konzentrationen (Φ 〉 0,52) aber größere Viskositätswerte als in der Scherströmung. Diese Differenzen lassen sich auf unterschiedliche Platzwechselmechanismen zurückführen. Bei Scherströmungen beobachtet man für die höchsten Konzentrationen einen Übergang vom viskosen zum kornartigen Fließen. In monodispersen Systemen ordnen sich dabei die Kugeln zu hexagonal dicht gepackten Schichten, die übereinander gleiten. Noch deutlicher macht sich der Einfluß des Strömungstyps bei Suspensionen mit Plexiglaskugeln in Öl bemerkbar. In der Scherströmung beobachtet man Scherentzähung, wohingegen in der Dehnströmung nach wie vor eine konstante Viskosität gemessen wird, deren Größe genähert dem Grenzwert des oberen newtonschen Bereichs bei der Scherströmung entspricht. Dies ist durch die größere Effektivität der Dehnströmung bezüglich der Desagglomerierung erklärbar. Wird bei den Glaskugel-Suspensionen das Suspensionsmittel Öl durch eine wäßrige Glucose-Lösung ersetzt, so findet man höhere Werte der relativen Viskosität. Es sind gewisse Hinweise dafür vorhanden, daß dies durch abstoßende Wechselwirkungskräfte hervorgerufen wird.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 44 (1957), S. 108-108 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 6
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three probands heterozygous for a mutant of apolipoprotein AI (apo AIMarburg, Utermann et al. 1982a) were detected by screening of 2282 unrelated individuals resulting an a frequency estimate of about 1/750 in the German population. All three probands with apo AIMarburg had hypertriglyceridemia (triglyceride above 250 mg/dl) and subnormal HDL-cholesterol (below 30 mg/dl), but no other lipoprotein abnormalities. The kindreds of two probands with AIMarburg were studied. The family data are consistent with an autosomal codominant inheritance of the trait. A total of 16 heterozygous blood relatives with the mutant AIMarburg were detected in these kindreds. Analysis of the plasma lipid and lipoprotein levels in relation to the apo AI phenotype was complicated by the high prevalence of diabetes mellitus and thyroid disease in one kindred and of hyperlipidemia in both kindreds. No consistent relationship between plasma lipid and lipoprotein levels, and the mutant apo AI could be demonstrated. Instead the mutant apo AI and the dyslipoproteinemia seem to co-exist independently in these kindreds. Three sibs with the homozygous apo E-2/2 phenotype were detected in one kindred, and all three sibs had subnormal LDL-cholesterol and beta-VLDL, e.g., the lipoprotein abnormality characterizing primary dysbetalipoproteinemia. Genetic apo E phenotypes and the apo AI mutant segregated independently, indicating that the structural gene loci for apo E and apo AI are not closely linked.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 16 (1977), S. 317-321 
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zusammenfassung Ausrichtungs- und Aggregationseffekte in Kugelsuspensionen mit viskoelastischer Suspensionsflüssigkeit werden aufgezeigt. Bei einem Teil der Bilder handelt es sich um Mikroaufnahmen von ebenen Schichtenströmungen zwischen zwei Glasplatten. Die Kugeln richten sich in Strömungsrichtung aus und kommen einander näher. Bei Berührung verschwindet die Rotationsgeschwindigkeit der Kugeln. Diese Ausrichtung und Anlagerung wird auch in der Dehn- und Rohrströmung beobachtet. Der Orientierungsvorgang ist ein Normalspannungseffekt. Nicht die absolute Höhe der ersten Normalspannungsdifferenz, sondern das Verhältnis der ersten Normalspannungsdifferenz zur Schubspannung ist der wesentliche Parameter. Auf praktische Folgerungen wird kurz hingewiesen.
    Notes: Summary Photographs are presented which demonstrate the alignment and aggregation effects in suspensions of spheres in viscoelastic media. Pictures were taken from plane shear flows between two glass plates. The spheres line up in flow direction and come into contact. If the spheres touch, the rotation ceases. This alignment and association was also observed and photographed in elongational and in pipe flow. The alignment process could be related to normal stresses. A further observation is that the ratio of the first normal stress difference to the shear stress is the determining parameter. Practical aspects are mentioned.
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Selenium Compounds. LXV. On Compounds of the Type (CH3O)3 SeX with X = F, Cl, Br, NO3, AlCl4Reaction of Se(OCH3)4 with SeX4(X = Cl, Br)(mole ratio 3:1) yields (CH3O)3SeX. The compounds (CH3O)3SeX (X = F, NO3) are formed by reaction of (CH3O)3SeCl with the silver salts AgF and AgNo3, respectively. (CH3O)3SeAlcl4 is prepared by reaction of (CH3O)3SeCl with AlCl3. Some properties of the synthezised compounds and the ir spectra are given. From their data deduction concerning the nature of the chemical bonds in the compounds (CH3O)3SeX are possible.
    Notes: Die Verbindungen (CH3O)3SeX mit X = Cl und br bilden sich durch Umsetzung von Se(OCH3)4 mit SeX4(Molverhältnis 3:1). Die verbindungen (CH3O)3SeF und (Ch3O)3SeNO3 entstehen bei der Reaction des Chlorids (CH3O)3SeCl mit AgF bzw. AgNO3. Das (Ch3O)3SeCl reagiert mit AlCl3 zu (CH3O)3SeAlCl4. Einige Eigenschaften der Verbindungen und die IR-Spektren werden mitgeteilt. Die IR-Spektren gestatten Aussagen zur Natur der Bindungsverhältnisse in den (CH3O)3 SeX-Verbindungen.
    Additional Material: 2 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 401 (1973), S. 179-184 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Selenium Compounds. LXVII. Preparation of Amides of the Selenious AcidBy reaction of [(CH3)2N]2SeO or (RO)2SeO with NH3, CH3NH2 and H2N—(CH2)2—NH2 the amides of the selenious acid (NH2)2SeO, (CH3NH)2SeO, and (CH2NH)2SeO are formed which are stable only at low temperatures. The thermic stability of the amides increases in the given order.
    Notes: Durch die Umsetzung von [(CH3)2N]2SeO bzw. (RO)2 SeO mit NH3, CH3NH2 und H2N—(CH2)2—NH2 entstehen die Amide der selenigen Säure (NH2)2SeO, (CH3NH)2SeO und (CH2NH)2SeO, die nur bei tiefen Temperaturen beständig sind. Die thermische Stabilität der Amide nimmt in der angegebenen Reihenfolge zu.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 404 (1974), S. 213-218 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Selenium Compounds. LXIX. On the Reactivity of Diphenyl Selenium Dihalides with Ammonia, Alkyl- and SilylaminesThe halides Ph2SeX2 (Ph = C6H5; X = Cl, Br) are reduced by NH3, MeNH2 and Me2NH (Me = CH3) at -60°C forming Ph2Se. The reaction of Ph2SeCl2 with Me3SiNMe2 yields Ph2Se(NMe2)Cl, whereas with (Me3Si)2NH the salt [Ph2Se=N=SePh2]Cl is formed. The infrared spectra are presented and discussed.
    Notes: Die Halogenide Ph2SeX2 (Ph = C6H5; X = Cl, Br) werden durch NH3, MeNH2 und Me2NH (Me = CH3) auch bei -60°C zum Ph2Se reduziert. Bei der Umsetzung von Ph2SeCl2 mit Me3SiNMe2 entsteht Ph2Se(NMe2)Cl, während sich mit (Me3Si)2 NH das Salz [Ph2Se = N = SePh2]Cl bildet. Die IR-Spektren werden mitgeteilt und im Hinblick auf die Bindungsverhältnisse diskutiert.
    Additional Material: 2 Tab.
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