Ferromagnetic resonance in Sr doped rare earth orthocobaltites, Ln1−xSrxCoO3†

FMR measurements have been carried out on several members of the Ln_1−xSrxCoO₃ (Ln = Rare earth) system. The results show that g_eff in these systems is around 1.25 independent of x as well as the rare earth ion. It is suggested that this unusual value of g_eff is due to the localized intermediate-spin Co³⁺ ions (t⁵_2g e¹_g) located at the top of the π^* band.     

Steady state and transient fluorescence studies of CaF2: Dy single crystals

The steady state and transient fluorescence spectra of CaF₂: Dy³⁺ have been studied using Ar⁺ and N₂ lasers in the temperature range 77–673 K and in the wavelength region 4500–9000 Å. The spectra show the presence of two types of centers (type A and type B) with decay times of 1.3 and 3.5 ms. The observed spectrum is mostly due to type A centers. Three new groups of fluorescence ⁴F_9/2−⁶H_11/2, ⁴F_9/2−(⁶H_9/2, ⁶F_11/2) and ⁴F_9/2−(⁶H_7/2, ⁶F_9/2) have been observed for type A centers, and a tentative assignment of the positions of the Stark levels of ⁶H_11/2, (⁶H_9/2, ⁶F_11/2) and (⁶H_7/2, ⁶F_9/2) has been made. The change in the intensity of the transitions with temperature and excitation wavelength are discussed.     

Majumdar-Papapetrou class of nonstatic cylindrically symmetric Brans-Dicke-Maxwell fields

We have obtained relations between certain components of the metric and the electromagnetic potentials for source-free Brans-Dicke-Maxwell fields described by a nonstatic cylindrically symmetric Einstein-Rosen metric. These are important, in the sense that they generate a class of solutions that in a way can be said to belong to the class generated by similar relations obtained by Majumdar [1] and Papapetrou [2] for generalized static Einstein-Maxwell fields. The relations have further been used to reduce the B-D Maxwell equations to B-D vacuum equations and vice versa.     

On slow motion of a sphere in a viscous liquid

Stokes’ and Seth’s solutions for the slow motion of a sphere in a viscous, incompressible liquid have been discussed from the viewpoint of the structure of the velocity field and its relation to the drag of the sphere. The problem is analysed from a different angle in this paper. It is believed that it throws more light on thephysics of the problem.     

Cerimetric determination of uranium Use of triphenylmethane dyes as internal indicators

The use of the triphenylmethane dyes (erioglaucine, eriogreen, and xylene cynol FF) as internal indicators in the cerimetric titration of uranium^IV has been investigated. The titration is possible in the cold with sufficient rapidity and accuracy, the indicator colour change appearing sharply at the equivalence point. The indicator reactions are rapid and reversible within a wide range of acidity, from 0.5N to 8.0N, unlike other indicators, e.g. diphenylbenzidine, -phenylanth-ranilic acid or ferroïn, which require specified conditions for their proper functioning. These indicators can also beused for titration of uranium^IV with eerie ammonium nitrate in perchloric acid medium (but not in nitric acid medium).     

Vanadametry

Summary We have found that sodium vanadate oxidises hydroxylamine quantitatively and rapidly to nitrous oxide, even at the room temperature, if the reaction is carried out in 5–6 N hydrochloric acid medium using copper sulphate as catalyst.One of the authors, K.Bhaskara Rao, desires to thank the Ministry of Education, Government of India, for the award of a ResearchScholarship, and the authorities of the Andhra University for providing the research facilities.See also Z. analyt. Chem.156, 180 (1957).     

Phthalocyanines as oxidation-reduction indicators

Summary Copper phthalocyanine tetrasulphonic acid has been found to work satisfactorily as an inside indicator in the cerimetric titration of hydro-quinone and metol. It has the advantage that the indicator correction in titrations with 0.01 N solutions of ceric sulphate is much less than with the ferroin indicator, amounting to only 0.02 ml for two drops of the indicator solution.Part II: See Z. analyt. Chem. 163, 1 (1958).     

Zirconyl-alizarin blue s complex a spectrophotometric study

Alizarin blue S in 0.5N hydrochloric acid and 10% acetone gives a coloured complex with zirconium salts, which is used for the estimation of zirconium. Measurements were made at 625 mμ and the interference of several cations and anions was studied     

自反Banach空间中一类广义集值强非线性变分不等式问题

在自反Banach空间中引进并研究一类具有集值映射的广义强非线性变分不等式问题,并且证明了这类变分不等式解的存在性定理。结果修正、改进和推广了文献Cho Y.J等人的主要结果。