A novel foam based separation strategy for extracting minute target impurities

The purpose of this study was to extract impurities from compounds using a simple separatory bottle to purify target compounds with a foam column and allow for the further characterization of impurities. Charged dyes were used as target compounds due to the ease of detection of dyes and isolated impurities. Foaming agents were used in a glass bottle with a modified cap to separate a target impurity using an appropriately charged ligand. By passing N₂ gas through the solution, the surfactants sodium dodecyl sulfate and cetylpyridinium chloride generated foams that separated the dyes, Methylene blue and Orange G, respectively, from a solution containing both dyes. Sodium dodecyl sulfate condensed Methylene blue from the solution with high purity while cetylpyridinium chloride condensed Orange G with less purity. A range of concentrations (0.01–0.5 mmol/L) of dyes were used for separation. The condensability (volume and/or concentration) of the target compound increased as its concentration decreased. This novel separation method is a simple, rapid, inexpensive, and effective way to prepare samples and allows for the characterization of these impurities using sensitive analytical detection techniques.     

Equivalent linear models for non-linear non-autonomous systems

Equivalence between a class of non-linear non-autonomous systems of second order and a linear model of lower order is established through a differential transformation relation. It is shown that this equivalence can be established only under a certain constraint on the non-linear functional parameters of the given system. The equivalence automatically leads to the first integral which then can be analyzed further to obtain the response of the system. The feasibility of obtaining closed form solutions through such analysis is illustrated by considering certain sub-classes of systems. Further, the practical value of the technique is demonstrated through an example.     

Equivalence conditions for classes of linear and non-linear distributed parameter systems

Equivalence of certain classes of second-order non-linear distributed parameter systems and corresponding linear third-order systems is established through a differential transformation technique. As linear systems are amenable to analysis through existing techniques, this study is expected to offer a method of tackling certain classes of non-linear problems which may otherwise prove to be formidable in nature.     

Some comments on a paper by R. THUMMEL and W. KLEMM: „Das Verhalten der Alkalimetalle zu den Metallen der Gruppe III B”︁

Experimental results concerning the phase diagrams of In with Li, Na, K, Rb and Cs are compared with theoretical predictions.     

Equivalent higher order linear and non-linear systems

The object of this study is to put forth the concept of equivalence of classes of linear and non-linear systems of higher order. In particular, the equivalence of classes of non-linear (non-autonomous/autonomous) systems of order n described by partial/ordinary differential equations with corresponding classes of linear systems of order (n + 1) is established through a differential transformation of the dependent variable. In view of the fact that the resulting linear systems are amenable to existing state-space techniques, this approach can be expected to be of value in the study of many non-linear problems arising in a variety of disciplines. The possible applications of the technique are illustrated with an example.     

Some observations on the liquid immiscible nature of the Iron-Indium and Aluminium-Indium Systems

Hydroxide Groups on Zeolites. IV. Formation of Hydroxide Groups by Reduction of Y-Zeolites Containing Transition Metal Ions The formation of hydroxide groups as result of the reduction is studied by IR spectroscopy on NiNaY, CuNaY, and ZnNaY zeolites. After transformation of the OH groups into OD groups it was found that D₂ reduces the transition metal ions at 350°C and that simultaneously the concentrations of two types of the hydroxides groups which are already present before this treatment are increased markedly, viz. the concentration of an acid species and that of a weakly acid species. In NiNaY and CuNaY zeolites, the reduction at 350°C proceeds much more slowly than in ZnNaY zeolites. The reduction of ZnNaY zeolites is connected with their transformation to ultrastable zeolites.