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  • 1
    ISSN: 1432-0495
    Keywords: Key words Soil samples ; Jordan ; Metal ions ; Multivariate analysis ; Principle component ; Dendogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A Multivariate analysis and principal component analysis was performed on 37 samples gathered from different regions in north Jordan. Twenty-eight descriptors (variables) for each sample were used in these calculations, among them were metal ion concentration, such as Pb, Cr, Co, Zn, Ca, Mg, Fe, Na, K, Al, Cu, Ni, Ti, Si and Mn. Other descriptors were pH, electrical conductivity (EC), and grain sizes. It was found that the samples form three clusters, namely, agriculture, industrial and waste treatment plane regions. Statistical analysis showed that the samples are classified into seven classes, with the majority of the samples classified into three clusters. The first three principal components explained 99.2% of the variance. This method offers a method to classify geographical regions on a pollution bases and to determine the possible sources of pollution for such regions. This study showed that some of the agricultural farms were remote from the pollution sources clusters with polluted regions such as industrial or waste treatment complexes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 19 (1982), S. 181-184 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spectra of several 2-methyl-6-R-disubstituted naphthalenes (R=H, Me, I, NO2, Cl, SO2Cl, OH, OMe, COMe, Br, F and NHCOMe), have been analysed. Chemical shift and coupling constant values of these compounds are presented. The proton chemical shifts have been found to correlate with the ortho parameter, Q.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 645-650 
    ISSN: 0749-1581
    Keywords: 1H NMR ; 13C NMR ; 19F NMR ; β-Diketones ; Tautomerism ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multinuclear NMR experiments on fluorinated β-diketones have furnished information on the various tautomers present in solution and their proportions. 2-Trifluoroacetyl-1-indalone in CDCI3 solution exists in the enol form, as a mixture of exocyclic and endocyclic cis-enols with the exocyclic form favoured, but in DMF-d7 solution the equilibrium shifts to 40% enol, 60% hydrate with the enol and hydrate being in slow exchange on the NMR time scale. 2-Trifluoroacetyl-1-tetralone in CDCI3 solution exists only as the enol forms, approximately equally populated, but in DMF-d7, unlike the indalone, no hydrate is formed although there is now 6% of the keto form present in slow exchange. The experimental results were compared with calculated data produced using molecular orbital simulations. These agree with the NMR results and predict that the tetralone enol tautomers are both significantly populated at room temperature but that the indalone exists primarily as the exocyclic enol. The oxygen-oxygen internuclear distance in the hydrogen bond was estimated from the OH proton chemical shift based on a calibration from solid-state data from model compounds, and agrees well with the predictions using the molecular mechanics approach.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 585-589 
    ISSN: 0749-1581
    Keywords: Ethanediol ; NMR ; Coupling constants ; Conformation ; Inverse detection ; Gradients ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H NMR spectrum of [13C]ethane-1,2-diol was measured at natural abundance using the 1H—13C inverse-detected HMQC method with magnetic field gradients. A limited solvent and temperature dependence study was undertaken and the vicinal 1H—1H coupling constants were related to those in model compounds. It is shown that the trans rotamer is significantly populated, in contradiction to some recent theoretical and experimental studies.
    Additional Material: 1 Ill.
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  • 5
    ISSN: 0749-1581
    Keywords: Schiff bases ; Tautomerism ; 13C NMR CP/MAS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C and 1H NMR spectra of six Schiff bases formed from 2-hydroxy-1-naphthaldehyde and substituted anilines were measured and assigned in a variety of solvents. Based on the 13C chemical shifts and 3J(CH,NH), the ratio of the keto-amine and phenol-imine tautomers was derived using both 13C chemical shifts and 1H-1H coupling constants, the two methods giving comparable results. The solid-state 13C NMR spectra of two of these Schiff bases were also measured and interpreted. Based on chemical shift assignments from solution NMR, which showed a relationship between certain shifts and the proportions of the tautomers, it has been shown that these compounds exist essentially as the keto-amine form in the solid, the tautomer previously shown to be the more thermodynamically stable.
    Additional Material: 1 Ill.
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  • 6
    Publication Date: 1999-09-22
    Print ISSN: 0943-0105
    Electronic ISSN: 1432-0495
    Topics: Geosciences
    Published by Springer
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