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  • 1
    Electronic Resource
    Electronic Resource
    Selective and sensitive extraction spectrophotometric method for the determination of vanadium (V) as a mixed ligand complex withN-phenyl benzohydroxamic acid and 4-(2-pyridylazo)resorcinol in non-aqueous media (1990)
    Springer
    Microchimica acta 100 (1990), S. 87-94 
    Details
    ISSN: 1436-5073
    Keywords: extraction ; spectrophotometric determination ; vanadium(V) ; PBHA ; PAR ; non-aqueous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A selective, sensitive and direct method for the spectrophotometric determination of vanadium in steels is developed in which vanadium is extracted withN-phenyl benzohydroxamic acid (PBHA) into chloroform from 5M hydrochloric acid medium followed by colour development by addition of 4-(2-pyridylazo)resorcinol (PAR) inN,N-dimethyl formamide (DMF). The vanadium(V)-PBHA-PAR mixed ligand complex shows maximum absorbance at 560 nm with a molar absorptivity 3.6 × 104 l mol−1 cm−1 and obeys Beer's law up to 2.0 μg/ml of vanadium. The composition of the mixed ligand complex is determined by Job's method of continuous variations which revealed a 1 ∶ 1 ∶ 1 ratio for V(V) ∶ PBHA ∶ PAR. This method can be directly applied for the determination of vanadium in steels, while in the case of titanium base alloys, after separation of titanium matrix it gives good results even at 50–200 μg of vanadium per gram level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244503
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  • 2
    Electronic Resource
    Electronic Resource
    Extractive spectrophotometric method for the determination of niobium in steels (1993)
    Springer
    Microchimica acta 111 (1993), S. 127-132 
    Details
    ISSN: 1436-5073
    Keywords: niobium ; extraction spectrophotometry ; ion-association systems ; xylometazolonium ; PAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A strongly coloured complex of niobium with PAR is formed in oxalate solutions and at pH 7.4 can be extracted into nitrobenzene as an ion-association complex with xylometazolonium ion (XMH), with a molar absorptivity of 46300 1 mol−1 cm−1 at 545 nm. In contrast to cationic extractants such as tetraphenylphosphonium or tetraphenylarsonium chloride, XMH is an effective extractant over a wide concentration range without any difficulties in either the separation of the phases or the absorbance of the reagent blank. Job's method of continuous variations revealed that the composition of the extracting species as 1 ∶ 1 ∶ 1 ∶ 1 for niobium ∶ oxalate ∶ PAR ∶ XMH. Based on this extraction, a highly sensitive and selective spectrophotometric method for the determination of niobium in various steels, after prior separation of iron, is described. 4-(2-Pyridylazo)resorcinol (PAR) reacts with the niobium tartrate complex in nearly neutral medium to form a red, water-soluble 1 ∶ 1 anionic complex [1]. PAR is an unselective reagent and one way of improving selectivity is by ternary and ion-association complex formation. The extraction of some highly coloured metal-PAR complexes with tetraphenylarsonium or tetraphenylphosphonium ion has been described [2, 3]. The PAR complex of niobium, which is formed in oxalate solutions has been shown to be extractable by chloroform using tetraphenylarsonium and phosphonium salts [4, 5]. However, in many of these extraction spectrophotometric procedures difficulties arise due to the delay in the separation of the two phases and significant absorbance of the reagent blank solution, particularly when concentrated solutions of reagents are used. The extraction of anionic complexes of Pd, V, and Cr with xylometazolonium (XMH) cation has been reported elsewhere [6–9]. In the present study we have tried to extract Nb(V) and it is observed that 1 ∶ 1 oxalatoniobium-PAR complex can be extracted with XMH. A method is proposed for the determination of niobium in standard steels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240175
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  • 3
    Electronic Resource
    Electronic Resource
    Association of thiocynate with reduced bovine albumin: Essential features of the binding sitesThis investigation was supported by grants from the National Institute of General Medical Sciences, U. S. Public Health Service (GM 08361), and the National Science Foundation (GB 7224) (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1487-1490 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1968.360061011
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  • 4
    Electronic Resource
    Electronic Resource
    4-Phenoxy-3,5-dinitrobenzoylpolyethyleneglycol: Reversible attachment of cysteine-containing polypeptides to polymers in aqueous solutions (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 383-392 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyethyleneglycol of molecular weight 6000 was treated with 4-phenoxy-3,5-dinitrobenzoyl chloride in warm toluene. The product of this reaction is a white crystalline solid containing 0.1-0.2 mmol of labile phenoxy groups per gram of polymer derivative. In aqueous buffers of pH 7, the phenoxydinitrobenzoyl polymer reacts rapidly with side-chain sulfhydryl groups of cysteine, but very slowly with other functional groups found in polypeptides, yielding peptide-polymer compounds in which the peptide and polymer are linked by a thiol-sensitive dinitrophenylene bridge. Both small synthetic peptides and the B-chain of bovine insulin thus linked to polyethylene glycol are soluble in water and in some organic solvents. An arginine-containing peptide bound to the polymer was hydrolyzed by trypsin at the arginyl bond, indicating that the linear polyethyleneglycol support does not restrict access of enzymes to bound peptides. Release of peptides from the polymer is rapidly accomplished by treatment with thiols at pH 7 in aqueous solutions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180214
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  • 5
    Electronic Resource
    Electronic Resource
    Quantitation of fatty acids and hydroxy fatty acids by gas chromatography/mass spectrometry. Predictively useful correlations of relative response factors with empirical formula (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 1018-1022 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Relative response factors (molar sensitivities relative to dibutyl phthalate) for homologous series of n-alkanes (C12—C26), trimethylsilyl esters of C10—C20 fatty acids (FAs) and bistrimethylsilyl derivatives of C8—C16 ω-hydroxy fatty acids (HOF As) were determined by integration of total ion chromatograms obtained using a conventional gas chromatograph-mass spectrometer in the electron impact ionization mode. For the alkanes up to C22 and for the FA-TMS derivatives up to C18 (C21 including the TMS carbons), response factors increased linearly with total number of carbons (r2 〉 0.99). The slope of this correlation (response factor = 0.0775n - 0.338, where n is the total number of carbon atoms in each analyte) is essentially identical with those determined in earlier studies for smaller molecules not containing silicon. For the HOFA derivatives up to C14 (C20 including TMS carbons), the molar response factors also increased linearly with total number of carbons, but for reasons not yet apparent the regression line for these homologs was different (response factor = 0.0330n + 0.456; r2 〉 0.99). Response factors for higher homologs in all three series fell below the regression line for the lower homologs, the deviation increasing with increasing molecular mass and increasing GC retention time. In all three series the upper limit to the linear portion of the correlation corresponded to the homolog whose GC retention time was ca 15 min under the conditions used; a high injection port temperature was found to be the most critical factor in extending the linear range of the correlation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300711
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of epoxy resin derived from cyanuric acid (1991)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 668-670 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Verfahren zur Synthese eines Triglycidylisocyanuratharzes in guter Ausbeute und Reinheit ausgehend von heterocyclischer Cyanursäure wird beschrieben. Reinheit und Struktur des Harzes werden durch Schmelzpunktbestimmung. IR- und NMR-Spektroskopie, Elementaranalyse sowie Bestimmung des Epoxidäquivalentes bestätigt.
    Notes: A procedure is described to synthesize heterocyclic cyanuric acid based triglycidyl isocyanurate resin in good yield and purity. The purity and configuration of the resin were confirmed by determination of the melting point, IR and NMR spectroscopy, elemental analysis, and epoxide equivalent.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1991.010421213
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  • 7
    Electronic Resource
    Electronic Resource
    Dielectric properties of a standard epoxy resin (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 134-135 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400215
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  • 8
    Electronic Resource
    Electronic Resource
    Measurement of ultrasonic velocity in resin solutions (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 526-529 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In Lösungen verschiedener Harze mit unterschiedlicher Konzentration wurde die Ultraschallgeschwindigkeit gemessen. Die erhaltenen Ergebnisse waren Grundlage zur Berechnung verschiedener physikalischer Parameter der Harzlösungen.
    Notes: In solutions of different resins the ultrasonic velocity was measured at different concentrations. The obtained results were used to evaluate some physical parameters of the resin solutions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400809
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  • 9
    Electronic Resource
    Electronic Resource
    Evaluation of some physical parameters of standard resins using X-ray diffraction (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 473-475 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Röntgenstreuung von Amino-, Epoxy-, Alkyd- und Esterharzen wurde untersucht. Aus dem diffusen Halo wurde ein effektiver Abstand der Polymerketten berechnet. Mit Hilfe der von Boyer und Miller vorgeschlagenen empirischen Korrelationen wurde die Querschnittsfläche der Kettenmoleküle ermittelt, und daraus wurden die Zahl der Atome zwischen zwei Verknüpfungen, der Steifheitsparameter der Kette und die isotherme Kompressibilität abgeschätzt.
    Notes: The X-ray diffraction of amino, epoxy, alkyd, and ester gum resins was investigated. The diffraction halo was used to compute an effective distance value in the polymers. With the help of the empirical correlation graphs suggested by Boyer and Miller the cross-sectional area of the chain molecules was evaluated, and from that the number of chain atoms per entanglement, the stiffness parameters of the chain, and the isothermal compressibility were estimated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400713
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  • 10
    Electronic Resource
    Electronic Resource
    Dielectric and electrical properties of epoxy resins - influence of epoxide value and molecular weight (1990)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 51-53 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die dielektrischen Eigenschaften von drei Epoxidharzen wurden in Abhängigkeit von der Frequenz und der Temperatur untersucht. Die Gleichstromleitfähigkeit der Proben wurde bei unterschiedlichen Temperaturen gemessen. Ein Vergleich der Ergebnisse zeigt, daß die dielektrischen Eigenschaften von der Epoxidzahl abhängen, während die Gleichstromleitfähigkeit hauptsächlich von der Molekülmasse der Epoxidharze bestimmt wird.
    Notes: The dielectric properties of three epoxy resins have been studied as a function of frequency and temperature. The de conductivity of the samples was measured at different temperatures. A comparison of the results shows that the dielectric properties are dependent on the epoxide value, while the de conductivity depends mainly on the molecular weight of the epoxy resins.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1990.010410113
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