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121.
A method is described for the analysis of a mixture of chlorides, chlorates and perchlorates by complexometric titration. It is based on the partial reduction of chlorates and the reduction of chlorates plus perchlorates respectively; the chloride formed can then be determined. 相似文献
122.
J. Castro J. Romero J. A. García-Vázquez A. Castiñeiras A. Sousa 《Transition Metal Chemistry》1994,19(3):343-346
Summary Electrochemical oxidation of nickel in an acetonitrile solution containing 2-pyrrole-[N-(2-hydroxy-4-methyl-phenyl)methylimine] (H2L) and 1,10-phenanthroline (phen) yielded Ni(HL)2·phen, whose crystal structure was determined by XRD. The nickel atom has a distorted octahedral geometry, and is coordinated to the phenolic oxygen and imino nitrogen atoms of two Schiff base ligands. The i.r. and u.v.-vis. spectra of the complex are discussed and related to the structure. 相似文献
123.
de Sousa M de Castro B Abad S Miranda MA Pischel U 《Chemical communications (Cambridge, England)》2006,(19):2051-2053
A simple set of five components was used to design molecular logic gates based on phthalimide-sensitised Tb(III) luminescence, including the first report of an enabled NOR (EnNOR) gate. 相似文献
124.
In a recent paper (Barros, Sousa in: Kodai Math. J. 2009) the authors proved that closed oriented non-totally geodesic minimal hypersurfaces of the Euclidean unit sphere have index of stability greater than or equal to n + 3 with equality occurring at only Clifford tori provided their second fundamental forms A satisfy the pinching: |A|2 ≥ n. The natural generalization for this pinching is ?(r + 2)S r+2 ≥ (n ? r)S r > 0. Under this condition we shall extend such result for closed oriented hypersurface Σ n of the Euclidean unit sphere ${\mathbb{S}^{n+1}}$ with null S r+1 mean curvature by showing that the index of r-stability, ${Ind_{\Sigma^n}^{r}}$ , also satisfies ${Ind_{\Sigma^n}^{r}\ge n+3}$ . Instead of the previous hypothesis if we consider ${\frac{S_{r+2}}{{S_r}}}$ constant we have the same conclusion. Moreover, we shall prove that, up to Clifford tori, closed oriented hypersurfaces ${\Sigma^{n}\subset \mathbb{S}^{n+1}}$ with S r+1 = 0 and S r+2 < 0 have index of r-stability greater than or equal to 2n + 5. 相似文献
125.
126.
127.
In this paper we study the critical behavior of the two-dimensional antiferromagnetic Ising model in both uniform longitudinal (H) and transverse (Ω) magnetic fields. Using the effective-field theory (EFT) with correlation in single site clusters we calculate the phase diagrams in the H−T and Ω−T planes for the square lattice. We have only found second order phase transitions for all values of fields and reentrant behavior was not observed. 相似文献
128.
Santiago Cabaleiro Rafael Calvo Jesús Castro J. Arturo García-Vázquez Lia M. B. Napolitano Otaciro R. Nascimento Paulo Pérez-Lourido Jaime Romero Antonio Sousa 《Journal of chemical crystallography》2008,38(1):71-75
Abstract The coordination chemistry of the ligand N-thiazol-2-yl-toluenesulfonamidate towards the copper(II) ion has been investigated using an electrochemical synthesis method.
The X-ray structure of this complex was elucidated and is discussed. The compound crystallised in the monoclinic crystal system,
P21/c space group with a = 17.3888(9), b = 16.3003(9), c = 18.3679(9) ? and β = 114.3640(10)°. Four bidentate sulfathiazolato anions bridge two metal centers in a paddle-wheel fashion,
with the nitrogen atoms as donors to give a dimeric species with a Cu···Cu distance of 2.7859(5) ?.
Graphical Abstract The coordination chemistry of the ligand N-thiazol-2-yl-toluenesulfonamidate towards the copper(II) ion has been investigated using an electrochemical synthesis method.
The X-ray structure of the product has been elucidated and is discussed. Sulfathiazolato anions act as bridging ligands to
give a dimeric species with a Cu···Cu distance of 2.7859(5) ?.
相似文献
129.
Structural characterization of MnNi and MnPt antiferromagnetic materials for spintronic applications
J.M. Teixeira J. Ventura J.P. Araujo J.B. Sousa V.S. Amaral B. Negulescu M. Rickart P.P. Freitas 《Journal of Non》2008,354(47-51):5275-5278
MnNi and MnPt become antiferromagnetic (AFM) when annealed at high enough temperatures, for which a face-centered cubic (fcc) to face-centered tetragonal (fct) structural transition occurs. Thus, structural information is essential when optimizing exchange bias in these materials. We performed structural (X-ray diffraction), magnetic (Magneto-Optical Kerr effect) and magneto-transport (magnetoresistance) measurements on MnNi based spin valves subjected to different annealing procedures and MnPt/CoFe bilayers with different MnPt thicknesses. We show that high annealing temperatures can in fact lead to the fct antiferromagnetic phase in both materials, but the annealing procedure is also an important factor on the obtained exchange field values. Also, MnPt/CoFe bilayers allowed us to probe the influence of average AFM-grain size on exchange bias. 相似文献
130.