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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1618-1628 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Separating mixtures of α-amino butyric acid (ABA) and isoleucine (Ile) by displacement chromatography with a cation exchange resin and an alkaline displacer leads to the formation of a displacement train, in which only ABA is recovered as a pure component, while Ile is recovered in a mixed band with ABA. The purity of the Ile band depends on the concentration of the displacer, and essentially pure Ile is obtained when the displacer concentration is reduced to a low value. The observed behavior is explained by considering the nonideality of the equilibrium uptake of these amino acids by the resin. An equilibrium model, representing the pure component isotherms, predicts variable selectivity and the occurrence of selectivity reversal in the two-component system. Analyses using this model based on the theory of coherent waves and a numerical solution of the conservation equations for the displacement chromatography process agree with the observed behavior, predicting the formation of “azeotropic” bands during the development of the displacement train. Such analyses are used to determine under what conditions a complete separation may be obtained for a given experimental system.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 584 (1990), S. 150-158 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal Structure of the Pnictide Oxides Na2Ti2As2O and Na2Ti2Sb2ONa2Ti2As2O and Na2Ti2Sb2O were synthesized in form of very easily hydrolysed metallic-grey powders by reaction of Na2O and TiAs resp. TiSb in sealed tantalum tubes under argon. The tetrahedral bodycentered crystallizing compounds from a modified anti-K2NiF4 structure type [1] (also called Eu4As2O-type [2,3]), space group I4/mmm (no. 139), with the lattice constants for Na2Ti2As2O: a = 407.0(2) pm, c = 1528.8(4) pm and for Na2Ti2Sb2O: a = 414.4(0) pm, c = 1656.1(1) pm.Magnetic measurements of powder samples of Na2Ti2Sb2O show antiferromagnetic interaction within the Ti - O-layers. Superconductivity was not found by ac-shielding method down to 4 K.
    Notes: Durch Umsetzung von Na2O und TiAs bzw. TiSb in verschweißten Tantalampullen unter Argon gelang die Darstellung der metallisch grauen und sehr hydrolyseempfindlichen Verbindungen Na2Ti2As2O bzw. Na2Ti2Sb2O. Sie kristallisieren tetragonal innenzentriert in einem modifizierten anti-K2NiF4-Typ [1] (modifizierter Eu4As2O-Typ [2, 3]), Raumgruppe I4/mmm (Nr. 139) mit den Gitterkonstanten für Na2Ti2As2O: a = 407,0(2) pm, c = 1528,8(4) pm und für Na2Ti2Sb2O: a = 414,4(0) pm, c = 1656,1(1) pm.Magnetische Messungen an Pulverproben von Na2Ti2Sb2O weisen auf antiferromagnetische Wechselwirkungen innerhalb der Ti - O-Schichten hin. Ein Test auf supraleitende Eigenschaften nach der AC-shielding-Methode erbrachte bis zu Temperaturen von 4 K keinen Hinweis für das Auftreten von Abschirmströmen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Intermetallic phases (ternary) ; lithium ; 4A metals ; 5B elements ; preparation ; crystal structure ; X-ray ; neutron scattering ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ternary Intermetallic Phases of Lithium, Transition Metals of the 4th Group and Elements of the 5th Maingroup with Statistical Metal Distribution in the „Cation“-SubstructureThe results of X-ray investigations and neutron diffraction on new and in some cases already known [1, 2] ternary intermetallic phases of Lithium with transition metals of the 4th group (b) and those of the 5th main group (X = P, As, Sb, Bi) will be reported. They crystallize in a partly „filled“ antifluorite type structure with a statistical Li/B-distribution in the tetrahedral sites. The structures are obviously stabilized by small amounts of enclosed d-elements.
    Notes: Es wird über Röntgenstrukturuntersuchungen und Neutronenbeugung an neuen und einigen schon bekannten [1, 2] ternären intermetallischen Phasen des Lithiums mit Elementen der 4. Nebengruppe (B) und Elementen der 5. Hauptgruppe (X = P, As, Sb, Bi) berichtet. Sie kristallisieren in einer teilweise „aufgefüllten“ Antifluorit-Struktur mit statistischer Li/B-Besetzung der Tetraederlücken, die offenbar durch den Einbau von geringen Mengen der Übergangsmetalle stabilisiert wird.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0887-3585
    Keywords: mass spectrometry ; time-of-flight ; nanoflow electrospray ; transthyretin ; retinol binding protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Complexes formed between transthyretin and retinol-binding protein prevent loss of retinol from the body through glomerular filtration. The interactions between these proteins have been examined by electrospray ionization combined with time-of-flight mass analysis. Conditions were found whereby complexes of these proteins, containing from four to six protein molecules with up to two ligands, are preserved in the gas phase. Analysis of the mass spectra of these multimeric species gives the overall stoichiometry of the protein subunits and provides estimates for solution dissociation constants of 1.9 ± 1.0 × 10-7 M for the first and 3.5 ± 1.0 × 10-5 M for the second retinol-binding protein molecule bound to a transthyretin tetramer. Dissociation of these protein assemblies within the gas phase of the mass spectrometer shows that each retinol-binding protein molecule interacts with three transthyretin molecules. Mass spectral analysis illustrates not only a correlation with solution behavior and crystallographic data of a closely related protein complex but also exemplifies a general method for analysis of multi-protein assemblies. Proteins Suppl. 2:3-11, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0887-3585
    Keywords: mass spectrometry ; time-of-flight ; nanoflow electrospray ; transthyretin ; retinol binding protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Complexes formed between transthyretin and retinol-binding protein prevent loss of retinol from the body through glomerular filtration. The interactions between these proteins have been examined by electrospray ionization combined with time-of-flight mass analysis. Conditions were found whereby complexes of these proteins, containing from four to six protein molecules with up to two ligands, are preserved in the gas phase. Analysis of the mass spectra of these multimeric species gives the overall stoichiometry of the protein subunits and provides estimates for solution dissociation constants of 1.9 ± 1.0 × 10-7 M for the first and 3.5 ± 1.0 × 10-5 M for the second retinol-binding protein molecule bound to a transthyretin tetramer. Dissociation of these protein assemblies within the gas phase of the mass spectrometer shows that each retinol-binding protein molecule interacts with three transthyretin molecules. Mass spectral analysis illustrates not only a correlation with solution behavior and crystallographic data of a closely related protein complex but also exemplifies a general method for analysis of multi-protein assemblies. Proteins Suppl. 2:3-11, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 605 (1991), S. 157-162 
    ISSN: 0044-2313
    Keywords: TICu[CuO2] ; synthesis ; crystal structure ; lattice energy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal Structure of TlCu[CuO2]By reaction of Tl2O3 and Cu2O in a sealed copper-type TlCu[CuO2] was synthesized; the orthorhombically bodycentered crystallizing compound forms a new structure type, space group Imma (no. 74), with the lattice constants a = 552.5 pm, b = 605.2 pm, c = 896.4 pm. The Madelung Part of Lattice Energy, MAPLE, as well as Effective Coordination Numbers, ECoN, these via Mean Effective Ionic Radii, MEFIR, were calculated.
    Notes: Durch Umsetzung von Tl2O3 und Cu2O im verschweißten Kupfertiegel gelang die Darstellung von TlCu[CuO2]; die Verbindung kristallisiert orthorhombisch innenzentriert in einem neuen Strukturtyp, Raumgruppe Imma (Nr. 74), mit den Gitterkonstanten a = 552,5 pm, b = 605,2 pm, c = 896,4 pm. Der Madelunganteil der Gitterenergie, MAPLE, sowie Effektive Koordinationszahlen, ECoN, diese über Mittlere Effektive Ionenradien, MEFIR, wurden berechnet.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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