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Abstract  

Some bis-hydrazine metal pyruvates of transition metal ions of the formula M[CH3COCOO]2 [N2H4]2, where M = Co, Ni, Zn or Cd, tris-hydrazine metal pyruvates of the formula M[CH3COCOO]2 [N2H4]3, where M = Co, Ni, Zn or Cd, and hydrazinium metal pyruvates [N2H5]2M[CH3COCOO]4, where M = Co or Ni have been prepared and the compositions of the complexes have been determined by chemical analysis. The magnetic moments and electronic spectra of the complexes suggest a high-spin octahedral geometry for them. Infrared spectral data of bis-hydrazine complexes indicate the bidentate bridging mode shown by hydrazine molecules and mono dentate coordination by pyruvate ions. However, in tris-hydrazine complexes the pyruvate ions are ionic in nature. In hydrazinium complexes two hydrazinium ions and four pyruvate ions show unidentate coordination mode resulting in six coordination around metal ions. Thermo gravimetry and differential thermal analysis in air reveal that most of the complexes decompose in one step to give the respective metal carbonate as the final residue. However, the hydrazinium complexes yield Co2O3 or NiO as the residue. The final residues were identified by their X-ray powder data. The X-ray powder diffraction patterns of each series of complexes reveal isomorphism among the series.

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Abstract  

The new hydrazinium lanthanide metal complexes of 2-pyrazinecarboxylic acid (HpyzCOO) of the formulae (N2H5)2[Ln(pyzCOO)5] · 2H2O (1), where Ln = La or Ce and (N2H5)3[Ln(pyzCOO)4(H2O)] · 2NO3 (2), where Ln = Pr, Nd, Sm or Dy have been synthesized and characterized by physico-chemical methods. The IR absorption bands of N–N stretching at 960 cm−1 unambiguously prove the existence of N2H5 + ions. The bonding parameters β, b1/2, % δ and η, have been calculated from the electronic spectroscopic (hypersensitive) bands of Pr(III) and Nd(III) complexes. All the complexes undergo endothermic followed by exothermic decomposition to leave the respective metal oxides as the end products. However, the DTA of the complexes 2 demonstrate rather sharp peak than the complexes 1, owing to overwhelming exothermicity, which may be due to the loss of both hydrazine and nitrate moieties in the same step. The X-ray powder diffraction studies reveal the existence of isomorphism among the member complexes.

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Summary  

We consider a generalisation of the Kurosh--Amitsur radical theory for rings (and more generally multi-operator groups) which applies to 0-regular varieties in which all operations preserve 0. We obtain results for subvarieties, quasivarieties and element-wise equationally defined classes. A number of examples of radical and semisimple classes in particular varieties are given, including hoops, loops and similar structures. In the first section, we introduce 0-normal varieties (0-regular varieties in which all operations preserve 0), and show that a key isomorphism theorem holds in a 0-normal variety if it is subtractive, a property more general than congruence permutability. We then define our notion of a radical class in the second section. A number of basic results and characterisations of radical and semisimple classes are then obtained, largely based on the more general categorical framework of L. M\'arki, R. Mlitz and R. Wiegandt as in [13]. We consider the subtractive case separately. In the third section, we obtain results concerning subvarieties and quasivarieties based on the results of the previous section, and also generalise to subtractive varieties some results for multi-operator group radicals defined by simple equational rules. Several examples of radical and semisimple classes are given for a range of fairly natural 0-normal varieties of algebras, most of which are subtractive.

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Combination of three techniques of thermal analysis (hot stage polarising microscope, DSC, Guinier-Lenne) enabled the determination of the polymorphic behaviour of tetra 1,2,4,5-X benzene (X=Cl, Br). Thermal, calorimetric and crystallographic characterizations have been carried out.

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Abstract

Filters are a fundamental tool in the study of convergence and completeness in topology. On the other hand, downsets have been used extensively for this purpose in the setting of pointfree topology. This paper investigates links between these in the asymmetric context, that is, for biframes and bispaces.

We present an appropriate kind of filter for the asymmetric setting, which we call a bifilter. These form a bispace, functorially so, which proves isomorphic to the spectrum of the downset biframe. As a corollary, downset biframes are seen to be isomorphic to the opens of the bifilter bispace. Both these correspondences are natural isomorphisms.

The join map from a downset biframe to its underlying biframe appears here as a universal strict quotient. We use it to show that the embedding of any T 0 bispace in its bifilter bispace is a universal strict extension.

Banaschewski and Hong [10] have established the importance of general filters for convergence and completeness in the pointfree setting. We conclude this paper with a discussion of an appropriate concept of general bifilter, and show that the right adjoint of the join map mentioned above is a universal general bifilter.

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Iskola a digitalizálódó világban

The School in a Digitalizing World

Educatio
Author:
Nóra Fazekas

Boxenbaum, E. & Jonsson, S. (2017) Isomorphism, Diffusion and Decoupling: Concept Evolution and Theoretical Challenges. In: R. Greenwood, C. Oliver, T. B. Lawrence & R. E. Meyer (eds) The SAGE Handbook of

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Abstract  

The phase diagrams of the binary system Ta2O5-K2TaF7 and the ternary system KF-Ta2O5-K2TaF7 were determined using the thermal analysis method. The system Ta2O5-K2TaF7 was measured up to 25 mol% of Ta2O5. Eutectic point is estimated to be at
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$x_{Ta_2 O_5 }$$ \end{document}
=0.14 and t=601°C. Crystallization of K2TaF7, K2Ta2O3F6 and a new phase was identified. The new phase shows isomorphism with K3Nb2F11O. In the ternary system four nonvariant equilibria points at 3 mol% of Ta2O5, 72 mol% of KF and 25 mol% of K2TaF7 at 715(1)°C; 6 mol% of Ta2O5, 44 mol% of KF and 50 mol% of K2TaF7 at 603(2)°C; 1 mol% of Ta2O5, 22 mol% of KF and 77 mol% of K2TaF7 at 704(1)°C and 8 mol% of Ta2O5, 8 mol% of KF and 84 mol% of K2TaF7 at 580(1)°C were proposed. Crystallization fields of KF, K2TaF7, K3TaF8, K3TaOF6, K4Ta2OF12 and K2Ta2O3F6 were considered.
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Abstract  

Hydrazine forms two different types of complexes with divalent metal ions and pyromellitic acid (H4pml) in aqueous medium: (i) hydrazinium complexes of formulae, (N2H5)2M(pml)·xH2O, where x = 3 for M=Ni and x = 4 for M=Co or Zn, and (N2H5)2Mn(H2pml)2, at pH 4.5, (ii) neutral hydrazine complexes with formulae, M2(pml)(N2H4) n ·xH2O where M=Co or Ni when n = 4 and x = 5 or 4 and M=Zn or Cd when n = 2, and x = 4 or 3 at pH 7, and M(H2pml)(N2H4xH2O where x = 4; M=Cu and x = 0; M=Hg, at pH 3, 7.5, respectively. All the complexes are insoluble in water, alcohol and ether. The N–N stretching frequency (990–1,007 cm−1 for coordinated hydrazinium ion and 956–985 cm−1 for bridged neutral hydrazine) indicates the nature of hydrazine present in the complexes. Simultaneously TG-DTA analysis indicates that hydrazinium complexes undergo dehydration and dehydrazination in a single step endothermally in the range of 289–300 °C whereas neutral hydrazine complexes undergo endothermic dehydration (~100 °C) followed by exothermic dehydrazination in the temperature range, 253–332 °C. The anhydrous metal carboxylates further decompose exothermally to leave the respective metal oxides or metal carbonates except zinc, which gives its oxalate as the end product. X-ray powder patterns indicate that even the complexes with the same formulation possess no isomorphism.

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References [1] B rown , L. G. , Stable isomorphism of hereditary subalgebras of C *-algebras , Pacific J. Math. , 71 ( 1977 ), 335 – 348

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Fora 13 2 4 C. M. Radaelli (2000): Policy Transfer in the European Union: Institutional Isomorphism as a

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