A scheme of separation of common inorganic cations and identification by filter paper strip chromatography

Summary The filter paper strip Chromatographic separation of the individual members of various groups of the qualitative analysis chart has been described. Use has been made of the ascending method, using 60% aqueous ethanol as solvent. The migrated ions are detected after their separation by the use of organic reagents.

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Zusammenfassung Die einzelnen Gruppen des qualitativen Kationentrennungsganges werden mit 60%igem Äthanol als Lösungsmittel papierchromatographisch nach der aufsteigenden Methode getrennt. Zum Nachweis der getrennten Ionen werden organische Reagentien benutzt.

     

Sodium-alizarin-3-sulphonate as a colloidal electrolyte

Summary During the study of the composition of metal chelates of sodium alizarin-3-sulphonate, it was realized that the colloidal nature of the reagent, especially in concentrated solutions, masks the true composition of the chelate. An investigation of the electrical conductance at various dilutions and temperatures shows that the reagent belongs to the class of colloidal electrolytes. It is recommended that for the study of the composition of chelates involving such chelating agents, extremely dilute solutions should be employed for physicochemical investigation, because under these conditions the reagent would behave as a true electrolyte.     

7-iodo 8-hydroxy quinoline 5-sulphonic acid (Ferron) as a colloidal electrolyte

Summary Electrical conductance studies have been performed to investigate the nature of aqueous solutions of 7-iodo 8-hydroxy quinoline 5-sulphonic acid (Ferron). The reagent has been found to behave as a colloidal electrolyte and does not obeyBeer's law in concentrated solutions. The curve between the square root of concentration and equivalent conductance is not linear and resembles those of colloidal electrolytes. The temperature of zero conductance has also been determined to be –32 C. The temperature coefficient per degree centrigrade per 100 of the conductance at 35 C ranges between 1.56 and 1.72.

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Zusammenfassung Elektrische Leitfähigkeitsuntersuchungen wurden an wä\rigen Lösungen von Ferron (7-Jod-8-hydroxyquinolin-5-sulfonsäure) durchgefÜhrt, um die Natur dieser Lösungen aufzuklären. Das Reagenz benimmt sich wie ein kolloider Elektrolyt und folgt nicht demBeerschen Gesetz in konzentrierten Lösungen. Der Zusammenhang zwischen Leitfähigkeit und Quadratwurzel aus Konzentration ist nicht linear und ähnelt dem kolloider Elektrolyte. Die Temperatur der Leifähigkeit 0 liegt bei –32 C. Der Temperaturkoeffizient in Prozenten der Leitfähigkeit bei 35 C liegt zwischen 1,56 und 1,72.

     

Thermodynamic properties of hard ellipsoid square-well fluid

The perturbation theory with non-spherical reference system is used for molecular fluid with angle-dependent square-well type potential. Simple analytic expressions are given for the thermodynamic properties such as the equation of state, excess free energy per particle, internal energy and internal heat capacity. The effects of anisotropy on the thermodynamic properties are discussed. The anisotropy effects increase with increase of density and decrease of temperature and depends on the anisotropy parameterx ₀.     

Statistical proofs of some matrix results

Using statistical arguments, proofs of some results in matrix theory are provided. Most of the proofs use results in linear statistical models and multivariate analysis. Some new results are also obtained in the process. In particular, several inequalities involving parallel sum of matrices are obtained.     

Counting triangle crossings and halving planes

Every collection oft≥2n ² triangles with a total ofn vertices in ℝ³ has Ω(t ⁴/n ⁶) crossing pairs. This implies that one of their edges meets Ω(t ³/n ⁶) of the triangles. From this it follows thatn points in ℝ³ have onlyO(n ^8/3) halving planes. The research of H. Edelsbrunner was supported by the National Science Foundation under Grant CCR-8921421 and under an Alan T. Waterman award, Grant CCR-9118874. Any opinions, findings and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the National Science Foundation.     

X-ray elucidation of 17α-pregna-2,4-dien-20-yne-(2,3-d) isoxazole-17β-ol

Synthetic pregnen steroid 17-pregna-2,4-dien-20-yne-(2,3-d) isoxazole-17-ol crystallizes in the orthorhombic space group P2₁2₁2₁, with a = 6.601(4), b = 10.530(4), c = 26.177(9) Å, and Z = 4. The structure was solved from Enraf Nonius CAD4 diffractometer data by direct methods and refined to R = 0.0399 for 2041 observed reflections (I > 2(I)). The molecule contains five rings of which rings A, B, and C are cyclohexene; ring D is cyclopentene; and ring E is heterocyclic cyclopentene. Ring A acquires the conformation of a half-chair; ring B tends toward a half-chair conformation with a bias toward a chair conformation that contains a hydrogen at C8 and an hydrogen at C9. Ring C acquires a near chair conformation with an hydrogen at C14. Ring D is a 13, 14-half chair, and ring E is a O3-envelope. Both the ring junctions A/B and A/E are quasi-trans, whereas the ring junctions B/C and C/D are both trans. The molecule as a whole is slightly convex toward the -side, with an angle of 16.7(2)° between the C10–C19 and C13–C18 vectors. Structural association is due to hydrogen bonding and stacking interactions.