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  • 1
    Electronic Resource
    Electronic Resource
    Molecular Complexes of Crown Ethers, Part 6: Complexes of Cryptand (2,2,2) and Kryptofix 5 with Some Acceptors (1999)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 17-26 
    Details
    ISSN: 1573-1111
    Keywords: UV-visible spectra ; charge transfer complex ; electron transfer ; TCNE ; DDQ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The UV-Visible spectra of Cryptand (2,2,2) and Kryptofix 5 as donors, and TCNE (tetracyanoethylene), DDQ (2,3-dichloro-5,6- dicyano-1,4 benzoquinone) and PA (picric acid) as acceptors were studied. Charge transfer (CT) spectra were obtained for these systems. It was found that potassium halides have little effect on the spectra. The major process was due to an electron transfer from the donor to the acceptor. This revealed itself in very high conductivity values for the CT solutions in comparison to that of the donor or the acceptor solutions. The infrared and proton NMR spectra of the complexes indicated a strong interaction between the donor and the acceptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008045927013
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular complexes of crown ethers. Part 3. Effect of cations on charge transfer complexes with TCNE (1995)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 23 (1995), S. 175-179 
    Details
    ISSN: 1573-1111
    Keywords: Crown ethers ; tetracyanoethylene ; UV-visible spectroscopy ; formation constant ; effect of cations on formation constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intermolecular charge transfer complexes (CT) of two crown ethers (CE), viz, B15C5 and DB18C6 (as donors), and tetracyanoethylene (TCNE), as acceptor, were studied in the UV-visible region in dichloroethane (DCE), at 298.2 K. The sequence of addition of the cation was varied in the case of B15C5 such that in one system the sequence was (CE+Cation)+TCNE and in the other (CE+TCNE)+cation. These two systems were found to be non-interchangeable, even under reflux conditions, giving differentK c values which were explained as being due to the different geometries of the CE. For the first sequence, the values most affected depended on the fit of the metal cation with the ether cavity, thus in B15C5, Na+ showed the greatest effect, while for DB18C6 it was K+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709575
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular Complexes of Crown Ethers, Part 5: Complexes of DB18C6 with Some Acceptors (1999)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 5-16 
    Details
    ISSN: 1573-1111
    Keywords: UV-visible spectra ; charge transfer complex ; formation constant ; DB18C6 ; TCNE ; DDQ ; halides ; electron transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The UV-Visible spectra of DB18C6 as a donor with TCNE (Tetracyanoethylene), and DDQ (2,3-dichloro-5,6-dicyano-1,4- benzoquinone) as acceptors were studied. Charge transfer spectra were obtained for these systems from which it was possible to calculate the formation constant, Kc. The effects of potassium halides were studied. This study shows that in the presence of the anion there is an electron transfer from the anion to the acceptor. This process is enhanced by the presence of the crown ether, CE. The formation of the anion salt with the acceptor, in the presence of the CE, follows the trend F = I 〉 Br 〉 Cl. It is also indicated in this study that the interaction between DB18C6 and the acceptor follow the trend DDQ 〉 TCNE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008096210619
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  • 4
    Electronic Resource
    Electronic Resource
    Life cycle and population dynamics of Annina mesopotamica (Ahmed), (Isopoda, Flabellifera) in the Shatt Al-Arab Region, Basrah, Iraq (1996)
    Springer
    Hydrobiologia 330 (1996), S. 119-130 
    Details
    ISSN: 1573-5117
    Keywords: Breeding biology ; population dynamics ; Isopoda ; Annina ; ovoviviparous ; Shatt Al-Arab ; Iraq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A population of the intertidal, ovoviviparous, cirolanid isopod Annina mesopotamica was studied at the Al-Chibassy tributary of the Shatt Al-Arab river from 14 May 1973 to 29 April 1974, and at the Garmat-Ali river of the Shatt Al-Arab, Basrah, Iraq from 5 November 1984 to 30 June 1986. Population density varied between 128 to 5760 individuals m−2 with a mean of 1218 m−2. Highest numbers occurred between June and September. Breeding extended for most of the year except November/January to February/March, although ovigerous females were present throughout the year. The incubation period varied with season, and was ca. 2 weeks during the warmest period, and about a month at lower temperatures. Egg numbers varied between 4 to 66 with mean 24. Brood size was linearly proportional to female size. The size frequency distribution of the population was polymodal with a predominance of females over males. Four different types of growth curves were found: exponential, concave, convex, and intermediate between concave and convex. Growth rate varied between 0.63 and 2.19 mm month−1. Mortality was higher among summer cohorts. Life span varied between 5 and 11 months.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020000
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular complexes of crown ethers, part 4: Complexes of crown ethers with picric acid (1996)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 25 (1996), S. 295-302 
    Details
    ISSN: 1573-1111
    Keywords: UV visible spectroscopy ; donor-acceptor charge transfer band ; crown ethers ; 15C5 ; 18C6 ; B15C5 ; BI8C6 and DB24C8 ; picric acid ; effect of salt on charge transfer band ; conformation of crown ether
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intermolecular charge-transfer spectra of seven crown ethers (CE), viz, 15C5, 18C6, B15C5, B18C6, DC18C6, and DB24C8, with picric acid (PA) were studied in the UV-visible region in 1,2-dichloroethane (DCE) at 298.2 K. The complex formation equilibrium constant values,K c, suggest that many factors contribute toK c, among them crown ether conformation, size and the presence of an aromatic ring in the CE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01044999
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  • 6
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    Studies of the correlation between wear behaviour and bonding strength in two types of ceramic coating (1998)
    Springer
    Details
    Publication Date: 1998-08-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 7
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    Life cycle and population dynamics of Annina mesopotamica (Ahmed), (Isopoda, Flabellifera) in the Shatt Al-Arab Region, Basrah, Iraq (1996)
    Springer
    Details
    Publication Date: 1996-09-01
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of Density and Gating of Delayed-Rectifier Potassium Channels on Resting Membrane Potential and its Fluctuations (1996)
    Springer
    The journal of membrane biology 154 (1996), S. 267 -274 
    Details
    ISSN: 1432-1424
    Keywords: Key words: Resting potential — Ion channel — Inactivation — Fluctuation —Xenopus oocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. The aim of this study is to evaluate directly, using a reduced experimental system, the nature of interactions between voltage-gated potassium channels and the resting membrane potential. Xenopus oocytes were injected with various concentrations of cRNA coding for a delayed-rectifier potassium channel Shaker-IR. The effects of the density and kinetics of the expressed channels on resting membrane potential is explored in isolated (``inside-out'') patches. The channel density is given in terms of maximal conductance (G max), measured from the maximal slope of the I-V curve under voltage clamp conditions. The capacitance of the experimental setup is approximately 1 pF. At high channel densities (G max 〉 10 pA/mV) the mean membrane potential is stabilized at approximately −60 mV. This resting membrane potential is more than 35 mV positive to the reversal potential for potassium ions under the same experimental conditions. Analyses of voltage clamp experiments indicate that at high channel densities the mean membrane potential is determined by the rates of channel activation and deactivation, but is not affected by the rates involved in the process of slow (C-type) inactivation. In contrast, at lower channel densities membrane potential is very unstable, and its mean value and amplitude of fluctuations are strongly affected by the process of slow (C-type) inactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002329900151
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  • 9
    Electronic Resource
    Electronic Resource
    Multivariate and principal component statistical analysis of contamination in urban and agricultural soils from north Jordan (1999)
    Springer
    Environmental geology 38 (1999), S. 265-270 
    Details
    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
    URL: http://dx.doi.org/10.1007/s002540050424
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  • 10
    Electronic Resource
    Electronic Resource
    Abelian varieties and the general Hodge conjecture (1997)
    Springer
    Compositio mathematica 109 (1997), S. 341-355 
    Details
    ISSN: 1570-5846
    Keywords: Hodge conjecture ; algebraic cycle ; abelian variety ; Kuga fiber variety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We investigate the relationship between the usual and general Hodgeconjectures for abelian varieties. For certain abelian varieties A, weshow that the usual Hodge conjecture for all powers of A implies thegeneral Hodge conjecture for A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000274922979
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