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1.
In order to investigate the relative effects of the differences between the structures and lipophilicities of 1, 10-dioxa-4, 7, 13, 16-tetra-azacyclo-octadecane (TA-18-crown-6) and the tetrabenzyl derivative of 1,10-dioxa-4, 7, 13, 16-tetra-azacyclo-octadecane (TBTA-18-crown-6) on their extraction-abilities and -selectivities for transition metal cations, constants of the overall extraction (logK
ex) of 1:1 (M:L) complexes, the distribution (K
D) for two diluents (CH2Cl2 and CHCl3) with different dielectric constants have been determined at 25 ± 0.1 °C. The magnitude of logK
ex is largely determined by that of K
D. The equilibrium constants of TA-18-crown-6 have been compared with those of TBTA-18-crown-6. It is found that:(i) logK
ex sequences of TA-18-crown-6 and TBTA-18-crown-6 for transition metals in CH2Cl2 lie in order: Fe3+ > Cu2+ > Mn2+ > Co2+ > Cd2+ > Ni2+ > Zn2+ and Fe3+ > Cu2+ > Co2+ > Mn2+ > Ni2+ > Cd2+ > Zn2+ respectively; (ii) the stability sequences of two types of tetra-aza-crown ethers with the transition metal cations in CHCl3 are the same as follows: Fe3+ > Ni2+ > Cu2+ > Co2+ > Zn2+ > Cd2+ > Mn2+, and (iii) unusual selectivities are observed for transition metal-tetra-aza-crowns, e.g. the high Fe3+/M
n+ selectivity factors (Sf) of TA-18-crown-6, except for the competitive-extractions for the special case in CHCl3 of TBTA-18-crown-6, it was found that the Mn2+/M
n+ values were relatively higher according to the other transition metal cations. A systematic sequence in these two types of solvents is not found for a given transition metal cation in terms of the variation of selectivity with the tetra-aza-crown ethers. The results provide alternatives for the rational design of other specific ligands on the transition metal cations. 相似文献
2.
A new definition for the symmetries of Itô and Stratonovich dynamicalsystem is given. Determining systems of symmetries for Itô andStratonovich systems have been obtained, and their relation has beendiscussed. It has been shown that some of the Lie point symmetries ofthe Fokker–Planck equation can be constructed using the symmetries ofItô dynamical systems. Conserved quantities can be found from thesymmetries of stochastic dynamical systems which do not arise from aHamiltonian. The results have been applied to an example. 相似文献
3.
The spectral structure of two parameter unbounded operator pencils of waveguide type is studied. Theorems on discreteness
of the spectrum for a fixed parameter are proved. Variational principles for real eigenvalues in some parts of the root zones
are established. In the case of n = 1 (quadratic pencils) domains containing the spectrum are described (see Fig. 1–3). Conditions in the definition of the
pencils of waveguide type arise naturally from physical problems and each of them has a physical meaning. In particular a
connection between the energetic stability condition and a perturbation problem for the coefficients is given. 相似文献
4.
E. Ühlein W. Scherman F. Asinger A. Warner P. Kratochvil G. Kirschstein H. Bergmann H. D. Cremer U. Grigull E. Schleitzer E. Best R. Honerjäger H. Schäfer K. -H. König A. Sippel Hj. Schönert W. Koch B. Frisch H. G. Kilian R. Hähnel H. H. Pfeiffer 《Colloid and polymer science》1966,213(1-2):157-174
Ohne Zusammenfassung 相似文献
5.
H. Enginar P. Ünak F. Yurt F. Zümrüt Biber 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(3):473-479
An oestrogen derivative 3,17-a-oestradiolyl propyl 1,4,8,11-tetraazacyclotetradecanyl-1-(4-methylbenzoic acid)ester (ESTCPTA) that is 3,17-a-oestradiolyl propinol coupled to 1-(4-methylbenzoic acid)1,4,8,11-tetraazacyclotetradecane (CPTA) was synthesized in five steps. The product was purified by recrystallization in ethyl alcohol, and analysed by NMR and IR spectroscopy. ESTCPTA was labeled with 99mTc and radio thin layer chromatography (RTLC) and radio-paper electrophoresis were used to determine the radiochemical yields. Specific activity was approximately 23.7 GBq/mmol and the labeling yield was over 95%. The biodistribution studies were performed on female Albino Wistar rats. The rats were sacricified by ether narcotization at certain time intervals and the activity of the organs was counted by a gamma counter. The activity per gram tissue was calculated and time activity curves were generated. 相似文献
6.
Y. D. Kurt G. S. Pozan İ. Kızılcıklı B. Ülküseven 《Russian Journal of Coordination Chemistry》2007,33(11):844-849
Mixed ligand complexes of dioxomolybdenum(VI) with 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemicarbazone (H2L) were prepared with the formula [MoO2(L)D] (D = H2O, methyl, n-butyl, and n-undecyl alcohol, DMF, DMSO, pyridine, 4-picoline, and 3,5-lutidine). The compounds were characterized by elemental
analysis, IR and 1H NMR spectroscopy. The thermal decomposition of the compounds were investigated by using TGA, DTG, and DTA methods in air,
and the thermal behavior depending on the second ligand molecule was discussed. A single crystal of the DMF coordinated complex
was studied by X-ray diffractometry.
The text was submitted by the authors in English. 相似文献
7.
Samples of nominal 18 carat and 21 carat gold jewelleries from the local market were non-destructively bulk analyzed using neutron activation analysis. Neutrons of 14 MeV energy were used with a fast pneumatic sample transfer system. The actual gold contents, as well as the composition of the base metals in these samples were determined. The fast neutron activation was found to be an efficient, quick and accurate method of characterizing the precious metal objects routinely in bulk, with a large sample throughput. The results demonstrate the commercial availability of the technique for non-destructive bulk analysis of precious metal objects. 相似文献
8.
Template reactions of 2,4-dihydroxy-, 2,5-dihydroxy-, 2-hydroxy-3-methoxy- and 2-hydroxy-4-methoxy-benzaldehyde with methoxy- and hydroxy-substituted salicylaldehyde S-methylthiosemicarbazones in the presence of NiCl2 and FeCl3 resulted in the corresponding hydroxy- and methoxy-substituted N1,N4-diarylidene-S-methylthiosemi-carbazone complexes. Characterization of the compounds, [Fe(L)Cl] and [Ni(L)], was accomplished by means of elemental analysis, conductivity and magnetic measurements, i.r. and 1H-n.m.r. spectra. A systematic trend has been observed for the chemical shift values of the aromatic protons in the spectra of complexes. 相似文献
9.
8-Hydroxyquinoline (8-HOQ) is known as an important chelating agent for several metal ions. This compound is practically insoluble in water. For this reason, in this study its water soluble sulfate salt has been used for complexing uranyl ions and the stability constants of the complex have been determined. The Irving-Rosotti method computing the Calvin-Bjerrum pH-titration data, was applied. Finally, the stability constants of the complex formed between (8-HOQN-H)2SO4 and uranyl ions were found to be lgK1=8.25 and lgK2=4.15, the overall stability constant being {ie55-1}. 相似文献
10.
Summary Let (W, H, ) be an abstract Wiener space and letR(w) be a strongly measurable random variable with values in the set of isometries onH. Suppose that Rh is smooth in the Sobolev sense and that it is a quasi-nilpotent operator onH for everyhH. It is shown that (R(w)h) is again a Gaussian (0, |h|
H
2
)-random variable. Consequently, if (e
i
,i)W
* is a complete, orthonormal basis ofH, then
defines a measure preserving transformation, a rotation, onW. It is also shown that if for some strongly measurable, operator valued (onH) random variableR, (R(w+k)h) is (0, |h|
H
2
)-Gaussian for allk, hH, thenR is an isometry and Rh is quasi-nilpotent for allHH. The relation between the stochastic calculi for these Wiener pathsw and
, as well as the conditions of the inverbibility of the map
are discussed and the problem of the absolute continuity of the image of the Wiener measure under Euclidean motion on the Wiener space (i.e.
composed with a shift) is studied.The research of the second author was supported by the Fund for the Promotion of Research at the TechnionDedicated to the memory of Albert Badrikian 相似文献