Study of Enol-Keto Tautomerism of N-(2-Hydroxy-1-Naphthylidene)anils

The enol-keto tautomerism of N-(2-hydroxy-1-naphthylidene)anilines was studied. In response to the action of salts (e.g. CaCl₂), in ethanolic solution the equilibrium is shifted extensively in the direction of the keto form; this allows determination of the concentration of the keto form and of the equilibrium constant of the process. In accordance with the Hammett equation, the equilibrium constant varies as a function of the constants a of the substituents on the aniline ring.     

FT-Far Infrared Study of Complexes Involving Schiff Bases and Phenols

Abstract

Long range inter—ring “zig—zag” coupling between C-4 and H-8 (J₄₈ ?1.5 to ?1.8 Hz) has been observed in some 2,4? and 2,3,4? haloquinolines at 75 MHz. The coupling is influenced by the 4-halo substituent.     

Quadratic prediction and quadratic sufficiency in finite populations

The problem of quadratic prediction for population quadratic quantities in finite populations has been considered in the literature. In this paper, we mainly aim at extending the ordinary quadratic prediction problems to a general case, and derive the representations of the two essentially unique optimal predictors: one is an optimal invariant quadratic unbiased predictor, and the other is an optimal invariant quadratic (potentially) biased predictor. Further, we show that the two predictors are nonnegative and reasonable by considering an extreme situation, and apply resulting conclusions to a special model with a compound symmetric variance matrix. In addition, we propose a notion of quadratic sufficiency with regard to the optimal prediction problems by employing materials derived in the first part, and investigate corresponding characterizations in detail.     

Functional data analysis for cash flow and transactions intensity continuous-time prediction using Hilbert-valued autoregressive processes

In this paper we use a functional autoregressive model as a robust predictor of the cash flow and intensity of transactions in a credit card payment systems. Intraday economic time series are treated as random continuous functions projected onto low dimensional subspace. Wavelet bases are considered for data smoothing. We compare two linear wavelet methods for the prediction problem of a continuous-time stochastic process on an entire time interval. Ex poste prediction is used to check the models.     

Hypercomplex derivative bases of polynomials in Clifford analysis

Convergence properties of hypercomplex derivative bases of special monogenic polynomials are studied. These new results extend and improve a lot of known works from the complex case to Clifford setting. Copyright © 2009 John Wiley & Sons, Ltd.     

Fragments with finiteness conditions in particular over group rings

Abstract length functions on groups were introduced by Lyndon [5]. In [2] Chiswell showed that for a group action on an IR-tree there is a length function associated with each point of the tree, and moreover any length function can occur in this way. This paper establishes necessary and sufficient conditions for two length functions to arise from the same action of a group on a tree.     

A general construction of nonseparable multivariate orthonormal wavelet bases

The construction of nonseparable and compactly supported orthonormal wavelet bases of L ²(R ⁿ ); n ≥ 2, is still a challenging and an open research problem. In this paper, we provide a special method for the construction of such wavelet bases. The wavelets constructed by this method are dyadic wavelets. Also, we show that our proposed method can be adapted for an eventual construction of multidimensional orthogonal multiwavelet matrix masks, candidates for generating multidimensional multiwavelet bases.      

Solvent Extraction of Ag(I) and Cu(II) with New Macrocyclic Schiff Bases

Two new macrocyclic Schiff bases (II) and (III) containing nitrogen ‐ oxygen donor atoms were synthesized by reaction between diethylene triamine or 2,2′‐(ethylenedioxy)bis(ethylamine) and the intermediate compound: 1,4‐bis(6‐methoxy‐2‐formylphenyl)‐1,4‐dioxabutane (I). Identification of these macrocyclic Schiff bases: 1,12, 15,18, 29,32 ‐ hexaaza ‐ [3,4;8,9;20,21;26,27‐tetra‐(6′‐methoxyphenyl)]‐5,8,22,25‐tetraoxa cyclo tetratriacosine‐1,11,18,28‐tetraene. (II) 1,12,21,32‐tetraaza‐[3,4;9,10;23,24;29, 30‐tetra‐(6′‐methoxyphenyl)]‐5,8,15,18,25,28,35,38‐octaoxa cyclo ‐ tetracontane‐1,11,21,31‐tetraene. (III) were determined by elemental analysis (LC‐MS), (IR) and (¹H and ¹³C‐NMR) spectroscopy. The liquid‐liquid extraction of metal picrates such as Ag⁺ and Cu²⁺ from aqueous phase to organic phase was carried out using these ligands. The effect of chloroform and dichloromethane as organic solvents over the metal picrate extractions were investigated at 25 ± 0.1 °C by using atomic absorption spectrometer.