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  • 1975-1979  (7)
  • 1978  (7)
  • Chemistry  (7)
  • 1
    Electronic Resource
    Electronic Resource
    The effect of antibiotic additions on the mechanical properties of acrylic cement (1978)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 12 (1978), S. 473-490 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Early work on hip prosthesis showed that the metal component would loosen in bone even when screws were used. This practice resulted in the death and resorption of the bone; thus cement was used in orthopedic surgery for firm implantation of prostheses. In recent years antibiotics have been added to the cement as a prophylaxis against infection.This research investigates the effects of antibiotics on the diametral tensile and compression strength of the cement. Samples made with 2 g of antibiotic per surgical packet of bone cement containing the antibiotics gentamicin, keflin, and a combination of the two were tested. These samples were aged at ambient temperature for periods of 1 day and 1, 2, 8, 13, and over 30 weeks.A statistical analysis using a two-way analysis of variance with interaction was conducted. It was concluded that the compression strength was affected by the antibiotic, and not by the aging period, but that there is an antibiotic-aging period interaction. The tensile strength is not affected by either the antibiotic or the aging period, and there is an antibiotic-aging period interaction. Current work being conducted will analyze additional factors and interactions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820120403
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. XPart IX, see [1].. On the metal complexation kinetics of two N4-macrocycles containing a pyridine ring (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2291-2296 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexation kinetics of the two macrocycles 1 and 2 with Co2+, Ni2+, Cu2+ and Zn2+ have been measured by pH-stat techniques. The rates are first order in metal and ligand concentration and depend upon the pH. This results from the different reactivities of the various protonated species of the macrocyclic tetraamines. The resolved rate constants are given in Table 2.In comparison with other 14-membered cyclic aliphatic tetraazasystems 1 and 2 react more slowly with metal ions. This might be a consequence of the more rigid structure induced by the pyridine ring.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610702
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  • 3
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. XIPart X, see [1].. Ring size effect on the complexation rates with transition metal ions (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2296-2306 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 12-16 membered tetraazamacrocycles 1-6 were synthesized, their protonation constants and complexation kinetics measured at 25° and I = 0.50. The results of Table 1 Show that pK3H is strongly influenced by the ring size whereas pK2H and pK1H are relatively insensitive to it. This can be understood in terms of electrostatic interactions of the positive charges when located on adjacent amino groups.The kinetics of complex formation between the macrocyclic ligands and several transition metal ions have been studied by pH-stat and stopped-flow techniques and the results have been analyzed as bimolecular reactions between the metal ion and the different protonated species of the ligands. The rate constants, given in Table 2, show that the macrocycles react less rapidly than analogous open chain amines. However, for a given protonated species of the ligand the rate of complexation follows the order Cu2+ 〉 Zn2+ 〉 Co2+ 〉 Ni2+ which parallels the sequence of their water exchange rates. For the diprotonated tetraamines LH22 reacting with Cu2+ the slower rates seem to be mainly a consequence of electrostatic interactions, since a correlation between logkLH2Cu and pK3H exists. For LH+, however, the complexation rates of a metal ion with the different macrocycles are all in one order of magnitude and do not depend in a regular way on the ring size or the basicity of the ligand. It is therefore suggested that in this case other factors such as unfavourable preequilibria must be considered as important.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610703
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  • 4
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. IXFor part VIII see [1].. Synthesis and properties of a new class of branched N4-macrocycles with an additional ligating group in the side chain (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1376-1387 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of Ni2+ the template reaction between 2,6-diacetylpyridine and 4-(2-dimethylaminoethyl)- or 4-(2-hydroxyethyl)-1, 7-diamino-4-azaheptane yields the complexes of either the open-chain ligand (3 and 11) or of the macrocycle (4 and 12). Reduction of the imino group in 4 and 12 with PtO2/H2 gives 5 and 13, respectively. In the case of the dimethylamino derivative 5 a mixture of at least four isomers was obtained. These were partially separated by chromatography on Sephadex SP-25 cation exchanger. Through demetalation of the Ni2+ complexes by cyanide the new macrocycles 7 and 14 were isolated, from which the corresponding Zn2+ and Cu2+ complexes were prepared.The macrocyclic Ni2+-complexes 4, 12, 5 and 13 can exist in two forms depending on the pH of the solution. At low pH protonation of the dimethylamino or hydroxy group in the side chain occurs. The metal ion is then bound to the four nitrogen atoms of the macrocycle in a square planar ligand field. At higher pH, however, the dimethylamino or hydroxy group (the last one also in its deprotonated form) can coordinate to one of the axial positions, whereby pseudooctahedral coordination geometry is induced. This reaction can be quantitatively described by a reversible acid-base equilibrium, the pKH of which greatly depends on the nature of the functional group, the degree of unsaturation of the macrocycle and the metal ion.The acid-base reaction and the concomitant structural change are a direct consequence of the unique combination of the rigid and kinetically stable structure of the macrocycle and of the flexible and kinetically labile functional group of the side chain.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610421
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational preferences of substituted cyclopentadienyl and heterocyclopentadienyl complexes (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 1578-1590 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die konformative Präferenz in substituierten Cyclopentadienyl- und Heterocyclopentadienyl-KomplexenMO-Berechnungen ergeben erhebliche Barrieren für die internen Rotationen in Thiadiborolen-Fe(CO)3- und Diazaborolen-Cr(CO)3-Komplexen. Die Gleichgewichtsgeometrien der zwei Moleküle sollten verschieden sein. Eine MO-Fragmentanalyse erklärt diese Ergebnisse und führt darüberhinaus zu einer ganz allgemeinen Analyse der Rotationsbarrieren in Heterocyclopentadienyl- und substituierten Cyclopentadienyl-ML3- und -ML2-Komplexen. Für letztere wird ein gleitender Übergang von η5- nach η2-Koordination vorhergesagt.
    Notes: Molecular orbital calculations indicate substantial barriers to internal rotation in thiadiborolene-Fe(CO)3 and diazaborolene-Cr(CO)3 complexes. The equilibrium geometry of the two molecules should also differ. A fragment analysis explains these results and leads to a general analysis of rotational barriers in heterocyclopentadienyl and substituted cyclopentadienyl-ML3 and -ML2 complexes. In the latter an interesting “slipping” from η5 toward η2 coordination is predicted.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781110439
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  • 6
    Electronic Resource
    Electronic Resource
    Cycloheptatriene and fulvene Cr(CO)3 complexes (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 1591-1602 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloheptatrien- und Fulven-Cr(CO)3-KomplexeIm Tricarbonylchrom(0)-Komplex von 1,6-Methano[10]annulen und in einigen verwandten Komplexen nimmt die Cr(CO)3-Einheit verglichen mit allen anderen Hexatrien-Cr(CO)3-Systemen eine anomale Orientierung relativ zum Polyen ein. Eine theoretische Analyse dieses Problems zeigt, daß diese Vorzugskonformation eng mit der Cycloheptatrien-Norcaradien-Valenztautomerie zusammenhängt. Mögliche Wege, die Rotationsbarriere in derartigen Komplexen zu beeinflussen, werden aufgezeigt. Vorzugskonformation, Rotationsbarriere und Abknicken der exocyclischen Methylengruppe in Tricarbonyl(η6-fulven)chrom(0) werden diskutiert und die Analyse wird auf die analogen Benzyl-Cr(CO)3- und Cyclobutadiencarbinyl-Fe(CO)3-Kationen ausgedehnt. Die Konformation dieser Komplexe wird solchen gegenübergestellt, die zwei Elektronen mehr enthalten.
    Notes: 1,6-Methano[10]annulene-Cr(CO)3 and several related complexes adopt an anomalous orientation of the Cr(CO)3 unit with respect to the polyene, compared to all other hexatriene-Cr(CO)3 complexes. A theoretical analysis of this problem shows that these conformational preferences are closely related to the cycloheptatriene-norcaradiene valence tautomerism. Several strategies for influencing the barrier to internal rotation in these complexes are presented. An analysis of the conformational preference, rotational barrier, and bending of the exocyclic methylene group in fulvene-Cr(CO)3 is also discussed. This is extended to the analogous benzyl-Cr(CO)3 and cyclobutadiene-carbinyl-Fe(CO)3 cations. Finally, the orientations of these complexes are contrasted to those containing two more electrons.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781110440
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  • 7
    Electronic Resource
    Electronic Resource
    A comparison of t-butyldimethylsilyl and trimethylsilyl ether derivatives for the characterization of urinary metabolites of prostaglandin F2α by gas chromatography mass spectrometryAbbreviations: tBDMS = t-butyldimethylsilyl ether; tBDMSOH = t-butyldimethylsilanol; BSTFA = bis-(trimethylsilyl)trifluoroacetamide. (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 346-356 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: t-Butyldimethylsilyl and trimethylsilyl ether derivatives of a series of methylated prostaglandin F2α metabolites have been compared with respect to their gas chromatographic and mass spectrometric properties. The t-butyldimethylsilyl derivatives had considerably higher retention indices (approximately 2.2 C units per silyl group) than their trimethylsilyl ether counterparts when analysed on the (non-polar) OV-1 stationary phase. Electron impact induced fragmentation patterns were strongly dependent upon the type of silyl ether employed and on the nature of the prostaglandin ω sidechain; the mass spectra of pairs of t-butyldimethylsilyl and trimethylsilyl ether derivatives were found to differ appreciably in several respects and to afford complementary structural information.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200050506
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