Spectrophotometric investigation of beryllium-2-hydroxy chalcone complex

2′-Hydroxy chalcone gave an intense orange-yellow color with beryllium in the pH range 5·5–6·2. The limits of identification and dilution were 0·125γ and 1:4 × 10⁵ respectively. A detailed spectro-photometric investigation of the color reaction was carried out. The complex obeyed Beer’s Law in the concentration range of 0·5–6·0p.p.m. at 460 nm. In the complex the ratio of metal to ligand is 1:2. The instability constant of the complex was 2·176 × 10^?6 at 28°. Oxalate, tartrate, citrate and fluoride interfered. The tolerance limits of iron, aluminium, chromium, uranium, thorium and vanadium are reported.     

Spectrophotometric studies of uranium (VI)-pongamol complex

The spectrophotometric studies of uranium (VI)-pongamol complex have been carried out in 50% aqueous ethanolic solutions. Pongamol produces a yellow complex with an aqueous uranyl salt solution, the complex is soluble in 50% aqueous ethanol. The complex is quite stable for 24 hours, the optical density remaining constant at pH 5·6–7·1. The complex obeys Beer-Lambert’s law at 390 mµ in the concentration range of 1 to 5 p.p.m. of uranium in solution. The molar composition of the pongamol uranium (VI) complex has been found to be 2:1, and its tentative structure has been suggested. The cations and anions which interfere in the estimation of uranium using pongamol have been indicated.     

Spectrophotometric studies of 6-methyl pyridine-2-aldoxime-iron (II) complex

6-Methyl pyridine-2-aldoxime produces with iron (II) solution a deep red complex soluble in 50% (by volume) aqueous acetone. The complex is stable at 10–45°C. and its colour intensity does not vary between pH 7·3 and 10·0. The complex obeys Lambert-Beer’s law at 520 mµ in the concentration range of 1·12 to 28·0 p.p.m. of iron.     

Spectrophotometric studies of copper (II)—bis-2-pyridyl glycol complex

An aqueous solution ofbis-2-pyridyl glycol forms a deep blue water-soluble complex with an aqueous solution of copper (II) salts. The complex has an absorption maximum at 600–650 mµ between pH range 3·0–8·7. The complex is stable for four days and obeys Lambert-Beer’s law in the concentration range of 5·08–50·80 ppm. of copper (II) in solution. The optical density of the complex remains constant between pH 3·8–5·9. The molar composition as determined by the method of continuous variation and by the slope ratio method has been found to be 1:1. The limits of interference due to some foreign ions during the estimation of copper (II) have been determined.     

Photometric study of iron-resacetophenone-oxime complex

A detailed study of iron-resacetophenone-oxime complex was made photometrically. It was found that the complex obeys Beer’s Law in the concentration range of 1 to 10 p.p.m. at 475 mµ and 550 mµ, both at pH 7·0 and 4·5. Iron (III) and the reagent combine in the molar ratio of 1:1 to form the complex. The sensitivity was found to be 0·01γ of iron per ml. The interfering ions are the same as with salicylaldoxime.     

An NMR study of the thiomalic acid complex of cobalt

An NMR study of the thiomalic acid complex of cobalt has been carried out at pH 2.6. The results show that the freshly prepared complex is paramagnetic and it gradually changes to the diamagnetic state, the reaction being complete in about 24 hours. It has been shown that the fresh complex has the hybridization sp³d², whereas the stable complex has the hybridization d₂sp₃. The results have been confirmed by measuring the change in the magnetic susceptibility of the complex with time.     

X-ray spectroscopic study of the thiomalic acid complex of cobalt

The cobalt K absorption spectrum has been studied in thiomalic acid complex of cobalt using a bent crystal X-ray spectrograph. It has been observed that the position of the absorption discontinuity taken with the freshly prepared complex differs from that of the discontinuity obtained with the complex kept in air for about 24 hours. It has been shown that this shift of the absorption edge is due to the change in valency of cobalt in the complex. The shape of the absorption discontinuity has revealed that the complex has an octahedral structure with the hybridizationsp ³ d ². On the molecular orbital theory the electronic configuration in this complex can be described asa _1g ^Emphasis>2 t _1u ^Emphasis>6 e _g ^Emphasis>4 t _2g ^Emphasis>4 e _g ^Emphasis>*2 .     

Experimental study of polyethylene under complex loading

Experiments have been carried out on thin-walled tubular samples of high pressure polyethylene for strain paths having the form of a two-section broken line. The validity of the isotropy postulate is demonstrated and the vector and scalar properties of the material are studied qualitatively.M. V. Lomonosov Moscow State University. Translated from Mekhanika Polimerov, No. 1, pp. 10–17, January–February, 1974.     

Polarographic study of Iron (III)-Resacetophenoneoxime complex

The polarographic behaviour of Iron (III)—Resacetophenoneoxime complex at pH 5.8 in a supporting electrolyte of 0.1 M sodium per-chlorate was studied. The results indicated a diffusion controlled irreversible reduction of the complex. The composition of the complex corresponded to the ratio metal to oxime as 1: 1. The stability constant of the complex was 2.78 × 10^?5.     

Reducibility of complex submanifolds of the complex euclidean space

Let M be a simply connected complex submanifold of . We prove that M is irreducible, up a totally geodesic factor, if and only if the normal holonomy group acts irreducibly. This is an extrinsic analogue of the well-known De Rham decomposition theorem for a complex manifold. Our result is not valid in the real context, as it is shown by many counter-examples. Received December 1, 1998; in final form March 31, 1999 / Published online July 3, 2000     

Torsion in the matching complex and chessboard complex

Topological properties of the matching complex were first studied by Bouc in connection with Quillen complexes, and topological properties of the chessboard complex were first studied by Garst in connection with Tits coset complexes. Björner, Lovász, Vre?ica and ?ivaljevi? established bounds on the connectivity of these complexes and conjectured that these bounds are sharp. In this paper we show that the conjecture is true by establishing the nonvanishing of integral homology in the degrees given by these bounds. Moreover, we show that for sufficiently large n, the bottom nonvanishing homology of the matching complex Mn is an elementary 3-group, improving a result of Bouc, and that the bottom nonvanishing homology of the chessboard complex Mn,n is a 3-group of exponent at most 9. When , the bottom nonvanishing homology of Mn,n is shown to be Z₃. Our proofs rely on computer calculations, long exact sequences, representation theory, and tableau combinatorics.