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991.
Summary Electrical conductance studies have been performed to investigate the nature of aqueous solutions of 7-iodo 8-hydroxy quinoline 5-sulphonic acid (Ferron). The reagent has been found to behave as a colloidal electrolyte and does not obeyBeer's law in concentrated solutions. The curve between the square root of concentration and equivalent conductance is not linear and resembles those of colloidal electrolytes. The temperature of zero conductance has also been determined to be –32 C. The temperature coefficient per degree centrigrade per 100 of the conductance at 35 C ranges between 1.56 and 1.72.
Zusammenfassung Elektrische Leitfähigkeitsuntersuchungen wurden an wä\rigen Lösungen von Ferron (7-Jod-8-hydroxyquinolin-5-sulfonsäure) durchgefÜhrt, um die Natur dieser Lösungen aufzuklären. Das Reagenz benimmt sich wie ein kolloider Elektrolyt und folgt nicht demBeerschen Gesetz in konzentrierten Lösungen. Der Zusammenhang zwischen Leitfähigkeit und Quadratwurzel aus Konzentration ist nicht linear und ähnelt dem kolloider Elektrolyte. Die Temperatur der Leifähigkeit 0 liegt bei –32 C. Der Temperaturkoeffizient in Prozenten der Leitfähigkeit bei 35 C liegt zwischen 1,56 und 1,72.相似文献
992.
993.
The monomeric titanium(IV) hydroxide complex, LTi(OH)(LH(3)= tris(2-hydroxy-3,5-di-tert-butylbenzyl)amine), which is sterically inhibited from condensation to a mu-oxo dimer, cannot be prepared by hydrolysis of the alkoxide, with K(eq)= 0.012 for hydrolysis of the titanium methoxide in THF. 相似文献
994.
Blue luminescence from (CdS)ZnS core-shell nanocrystals 总被引:6,自引:0,他引:6
995.
Rautaray D Sanyal A Adyanthaya SD Ahmad A Sastry M 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6827-6833
The total biological synthesis of SrCO3 crystals of needlelike morphology arranged into higher order quasi-linear superstructures by challenging microorganisms such as fungi with aqueous Sr2+ ions is described. We term this procedure "total biological synthesis" since the source of carbonate ions that react with aqueous Sr2+ ions is the fungus itself. We believe that secretion of proteins during growth of the fungus Fusarium oxysporum is responsible for modulating the morphology of strontianite crystals and directing their hierarchical assembly into higher order superstructures. 相似文献
996.
Aryloxytitanatranes [N(CH(2)CH(2)O)(3)]Ti[OC(6)H(2)-2,4-(t)()Bu(2)-6-CHPh(3)(-)(n)()(C(6)H(2)-3,5-(t)()Bu(2)-2-OH)(n)(-)(1)] (1, n = 1; 2, n = 2; 3, n = 3) containing aryloxides derived from substituted triphenylmethanes are formed in high yield in the reactions of the corresponding phenols with tert-butoxytitanatrane [N(CH(2)CH(2)O)(3)]Ti(O(t)()Bu). The aryloxytitanatranes adopt monomeric, trigonal bipyramidal structures, as confirmed by X-ray crystallography for 1 and 2. The compounds with pendant phenol groups display fluxional behavior due to interchange of the bound phenoxide with the free phenol groups, most likely via a mechanism involving displacement of one arm of the nitrilotriethoxide by the dangling phenol group. The amidotitanatrane [[N(CH(2)CH(2)O)(3)]Ti(NEt(2))](2) reacts with the bisphenol PhCH(C(6)H(2)-3,5-(t)()Bu(2)-2-OH)(2) to give a crystallographically characterized fully metalated cyclic octatitanium complex of the formula [PhCH(C(6)H(2)-3,5-(t)()Bu(2)-2-O)(2)Ti(2)[(OCH(2)CH(2))(3)N](2)](4) (4). The structure of 4 reveals a metallamacrocycle (minimum ring size = 28 members) consisting of four repeating unsymmetrical dititanium units. In each dititanium unit, there is an unprecedented slippage of the nitrilotriethoxide ligand such that both triethanolamine nitrogens coordinate to only one of the two titaniums, while the bisphenoxide is coordinated only to the other titanium. The propensity of the polyphenoxide ligands to chelate is attributed to favorable pi-bonding interactions attainable in the eight-membered chelate rings. 相似文献
997.
Biosynthesis of CaCO3 crystals of complex morphology using a fungus and an actinomycete 总被引:1,自引:0,他引:1
The biosynthesis of CaCO3 by reaction of aqueous Ca2+ ions with a fungus, Fusarium sp., and an actinomycete, Rhodococcus sp. (both plant organisms), is described. In the case of the fungus, cruciform-shaped calcite crystals are obtained (SEM picture A) while the actinomycete yielded the unstable polymorph of CaCO3, vaterite (SEM picture B). Specific proteins secreted by the microorganisms are responsible for the morphology and crystallography control observed. A highlight of this approach is that the microorganisms also provide CO2 for reaction with the Ca2+ ions, making the crystals completely biogenic. 相似文献
998.
A metallamacrocycle containing twelve Zn2+ ions, making it the largest member of a family of pyrazole-bridged cyclic metal clusters, has been synthesized and structurally characterized from the reaction of [Zn(ClO4)2] with 5-methyl-3-phenylpyrazole, 2-mercaptoethanol, and NaOH. 相似文献
999.
K. K. Seth 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):563-565
Charmonium spectroscopy is one of the best means of making precision study of QCD, the strong-interaction component of the Standard Model of particle physics. Recent progress in the study of charmonium, the need for additional precision data, and the opportunities that the new facilities offer, are discussed.Received: 30 September 2002, Published online: 22 October 2003PACS:
12.38.Qk Quantum chromodynamics: Experimental tests - 12.39.Pn Potential models - 13.25.Gv Decays of
,
, and other quarkonia - 14.40.Gx Mesons with S = C = B = 0,
GeV (including quarkonia) 相似文献
1000.
Ultrabright supramolecular beacons based on the self-assembly of two-photon chromophores on metal nanoparticles 总被引:2,自引:0,他引:2
Stellacci F Bauer CA Meyer-Friedrichsen T Wenseleers W Marder SR Perry JW 《Journal of the American Chemical Society》2003,125(2):328-329
Silver nanoparticles coated with a self-assembled layer of approximately 2500 chromophoric alkylthiol ligands, that exhibit a huge per particle two-photon absorption cross section (2.7 x 10-45 cm4 s photon-1) and a high fluorescence quantum yield (0.33), are reported. Polyfunctionalized variants of these nanoparticles have been produced that show reasonable solubility in water/ethanol mixtures. By virtue of the large number of tethered chromophores, these particles act as strongly two-photon absorbing nanobeacons and may have applications in fluorescence imaging and sensing. 相似文献