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1.
M. García del Muro Z. Konstantinović M. Varela X. Batlle A. Labarta 《Journal of magnetism and magnetic materials》2007
Granular films composed of nanometric Co particles embedded in an insulating ZrO2 matrix were prepared by pulsed laser deposition in a wide range of Co volume concentrations (0.06<xv<0.42). High-resolution electron microscopy (HREM) shows very sharp interfaces between the crystalline particles and the amorphous matrix, with no evidence of intermixing. The mean particles size and width of the distribution determined by fitting the low-field magnetic susceptibility and magnetization curves in the paramagnetic regime to a distribution of Langevin functions are in agreement with the parameters extracted from direct TEM observations. Ferromagnetic correlations between Co particles are evident in the field-cooled state when increasing Co concentration. The effective anisotropy constant estimated from magnetic measurements is about two orders of magnitude larger than the bulk value, and decreases as particle size increases. 相似文献
2.
Cheshmedzhieva D Ivanova P Stoyanov S Tasheva D Dimitrova M Ivanov I Ilieva S 《Physical chemistry chemical physics : PCCP》2011,13(41):18530-18538
Absorption and fluorescence spectra in acetonitrile for a series of substituted aryl hydrazones of N-hexyl-1,8-naphthalimide are studied with the aim of potential application of the compounds for enzyme activity localization. The influence of the substituents on the spectral characteristics has been evaluated. The absorption and fluorescence energies of substituted aryl-1,8-naphthalimide hydrazones have been calculated with the PCM TDDFT formalism. The M06 and PBE0 functionals, combined with the 6-31+G(d) atomic basis set, have been found to accurately model the excited state properties of the present set of solvated fluorophores. Absorption and fluorescence spectral characteristics have been rationalized in terms of experimental and theoretical electronic indices in order to assess their predictive abilities for application in designing analogues with good emitting properties. An excellent linear dependence is established between the experimental fluorescence and Hammett σ(p)(+) substituent constants and on the other hand σ(p)(+) constants correlate with the theoretically calculated values for the electrostatic potential at nuclei (EPN). A model for predicting the fluorescence properties of substituted hydrazones by means of EPN is drawn, including the polysubstituted derivatives, where Hammett constants are not applicable. 相似文献
3.
Kolev T Koleva BB Stoyanov S Spiteller M Petkov I 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(5):1087-1096
Counterions affect on the substructures formation in the case of the merocyanine dye, 1-methyl-4-[2-(4-hydroxyphenyl)ethenyl)]piridinium] hydrogensquarate both in gas and condense phase. Spectroscopically and structural elucidation of these aggregates have been performed, using solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids as a nematic liquid crystal suspension, UV-vis spectroscopy, HPLC tandem ESI mass spectrometry, (1)H and (13)C NMR, TGV and DSC. Quantum chemical DFT calculations have been carried out as well. Experimental and theoretical data are compared with analogous ones of corresponding iodide salt of dye studied. 相似文献
4.
Trond A. Abrahamsen Vegard Lima Olav Nygaard Stanimir Troyanski 《Milan Journal of Mathematics》2016,84(2):231-242
We study smoothness and strict convexity of (the bidual) of Banach spaces in the presence of diameter 2 properties.We prove that the strong diameter 2 property prevents the bidual from being strictly convex and being smooth, and we initiate the investigation whether the same is true for the (local) diameter 2 property. We also give characterizations of the following property for a Banach space \({X}\): “For every slice \({S}\) of \({B_X}\) and every norm-one element \({x}\) in \({S}\), there is a point \({y \in S}\) in distance as close to 2 as we want.” Spaces with this property are shown to have non-smooth bidual. 相似文献
5.
The mechanism and stereochemistry of δ-C atom functionalisation in the reactions of secondary straight-chain aliphatic alcohols with lead tetraacetate, ceric ammonium nitrate, and heavy metal (Pb4+, Hg2+, Ag+) salts (AcO)?1, O2?, CO32?-halogen (I2, Br2, Cl2) combinations are discussed. By demonstrating the intermediacy of 5-bromo-2-hexanol, it was confirmed that the dark silver oxidebromine induced cyclisation of 2-hexanol (and alcohols in general) involves (as the other hypohalite reactions) intramolecular 1,5-hydrogen abstraction by alkoxy radicals and formation of δ-bromohydrins. A novel and simple procedure for obtaining tetrahydrofurans from alcohols by way of the hypochlorite reaction, using silver or mercuric salts and chlorine, is described. 相似文献
6.
A short, efficient, and high-yielding synthesis of 4-aryl-2-aminopyridine derivatives has been developed. The route employs two palladium-catalyzed processes, the Suzuki reaction and the Buchwald–Hartwig amination, as the key steps. The same approach has been used for preparation of the corresponding quinoline derivatives. In addition, a brief study of biological properties showed the anticancer potential of these compounds. 相似文献
7.
S. S. Konstantinović B. C. Radovanović Z. B. Todorović S. B. Ilić B. V. Konstantinović 《Chemical Papers》2007,61(6):485-489
Metal complexes of some divalent metal ions (Co, Ni, Cu, Zn, Hg, and Pd) with isatin-β-thiosemicarbazone (ITS) as the Schiff base have been investigated potentiometrically and spectrophotometrically. The dissociation
constants of the ligand and formation constants of the metal complexes, as well as the corresponding thermodynamic functions
(ΔG, ΔH and ΔS) have been determined at different temperatures in ethanol—water solution. The full stability constants were also evaluated
spectrophotometrically by the Job method. The experimental results indicate that Cu(II), Zn(II), Pd(II), and Hg(II) form one-to-one
molecular complexes (ML) with the studied ligand, whereas Co(II) and Ni(II) form both ML and ML2 species. 相似文献
8.
The diffraction maxima (001) and (100) of the Mn1.11Al0.89 alloy have been measured by the neutron powder diffraction method in the temperature range from 23 to 427 C. The Curie temperature is found to be (404 ±2)°C. Temperature dependence of the magnetic structure factor gave the critical exponent β = 0.31±0.02.The disorder parameter has been found to decrease with the temperature. A convenient expression describing this behaviour has been proposed and discussed. 相似文献
9.
The spontaneous magnetization of the sublattice vs temperature in the antiferromagnetic NiO was measured by the neutron diffraction method. Temperature changes of the Bragg peaks (111), (222), (333) and (444) with the wavelengths of neutrons , , and , respectively were simultaneously investigated by the neutron time-of-flight spectrometer. On the basis of these measurements, the transition temperature from the antiferromagnetic into the paramagnetic phase was determined, TN = (523 ± 1)°K. The temperature function of the (111) magnetic peak intensity has been accepted to be I ~ (TN?T)2β. According to the present measurements the critical point exponent is 0.33 ± 0.020.04. 相似文献
10.
Zorica M. Bugarčić Biljana Mojsilović Ljiljana Marjanović Stanimir Konstantinović 《Monatshefte für Chemie / Chemical Monthly》2000,131(10):1091-1096
Summary. The reaction of some alkenols with tetrachloromethane in the presence of a radical initiator was investigated. Regarding
the effects of structural features of the starting alkenol (number and position of methyl substituents at the double bond
and at the carbinol carbon atom, constitutional relationship between the double bond and the hydroxyl group) there are two
possible competing reactions: addition and cyclization. In the case of the simplest alkenols (without substituents and with
a more remote double bond) addition occurs; mono- and disubstituted secondary and tertiary Δ4- and Δ5-alkenols cyclize in high yields to give the corresponding cyclic ethers.
Received March 17, 2000. Accepted (revised) May 31, 2000 相似文献