On the density of various classes of groups

Let $\text{T}$ be a subset of the set of all isomorphism classes of finite groups. We consider the number F_$\text{g}$(x) of positive integers n≤x such that all groups of order n lie in $\text{T}$. When $\text{T}$ consists of the isomorphism classes of all finite groups of any of the following types, we obtain an asymptotic formula for F_$\text{g}$(x): cyclic groups, abelian groups, nilpotent groups, supersolvable groups, and solvable groups. In the course of the arguments, we also obtain, for almost all n, a lower bound for the number of groups of a given order n.     

Polarographic behaviour of zinc in sodium formate solution

Summary A polarographic determination of Zinc can be successfully performed in 1 M sodium formate solution (pH 7.0) as supporting electrolyte using 0.005% of gelatin as maximum suppressor. Well defined waves are obtained for 1–6 mM of zinc and various anions do not cause any interference. The method is also suitable for the determination of zinc and mangenese in presence of each other.

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Zusammenfassung Zur polarographischen Zinkbestimmung wird eine 1 m Natriumformiatlösung (pH 7,0) und 0,005% Gelatine als Maximumunterdrücker empfohlen. Im Bereich von 1–6 mMol Zink werden gut ausgebildete Stufen erhalten. Verschiedene Anionen stören nicht. Das Verfahren kann auch zur Bestimmung von Zink und Mangan nebeneinander angewendet werden.

     

Studies on nickel(II) complexes of N-aryl thioureas

The preparation and properties of the crystalline compounds of the type NiL ₄Cl₂, NiL ₂Cl₂ and NiLCl₂ (L=N-aryl thioureas) are described. Analytical, conductometric, magnetic and spectral data (infrared and electronic)_show that complexes of the type NiL ₄Cl₂ possess octahedral structure and those of NiL ₂Cl₂ and NiLCl₂ are characterised as distorted octahedral in solid state. The ligand field parametersD _q ,B and calculated from electronic spectral data, suggest a weak field for all the ligands. Metal sulphur bonding for all ligands is adduced from infrared and far infrared spectral studies.

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Untersuchungen an Nickel(II) Komplexen von N-Aryl-thioharnstoff Derivaten

Zusammenfassung Darstellung und Eigenschaften der kristallinen Verbindungen vom Typ NiL ₄Cl₂, NiL ₂Cl₂ und NiLCl₂ (L=N-Arylthioharnstoff) werden beschrieben. Magnetische Eigenschaften, Leitfähigkeitsmessungen, analytische und spektroskopische Daten beweisen, daß die Komplexe vom Typ NiL ₄Cl₂ oktaedrische Struktur besitzen; die Komplexe vom Typ NiL ₂Cl₂ und NiLCL₂ weisen eine verzerrt oktaedrische Geometrie auf. Die Ligandenfeld-ParameterD _q ,B und , die aus Elektronenanregungsspektren berechnet wurden, zeigen ein schwaches Feld für alle untersuchten Liganden an Aus Untersuchungen der Spektren des IR und fernen IR folgt, daß die Komplexe eine Metall—Schwefel-Bindung aufweisen.

     

Electronic transitions of aluminum monoxide

In view of the renewed interest in the electronic spectra of the AlO molecule, which is of both astrophysical and aeronomical interest, a systematic analysis of the available spectral data is carried out. A valid and consistent set of vibrational constants are derived for the A and D states of the molecule. Potential curves (Morse and RKRV) are obtained for the X, A, C and D states. Franck-Condon (FC) intensity factors and r-centroids are reported for the CX, DX and DA transitions. The calculated FC-factors are used to explain the intensity distribution of the bands in the various systems.     

Volumetric estimation of uranium-part III, with ceric sulphate

Summary The use of diphenylamine, diphenylbenzidine, diphenylamine sulphonate and N-phenylanthranilic acid as inside indicators in the titration of uranium IV salt with ceric sulphate has been investigated in detail. Experimental conditions have been defined under which these indicators function efficiently.     

CHLOROPHYLL a FLUORESCENCE YIELD IN LIVE CELLS AND SOLUTIONS

Abstract— Fluorescence yields of chlorophyll a in ether and methanol solutions ( F_s ), on the one hand, and in Chlorella pyrenoidosa and Anacystis nidulans cells (F_c), on the other hand, were determined by excitation at 600 mμ (instead of at 436 mμ, as was done in earlier research in our, and other, laboratories). The ratio of the yields Fs/F_c , was found to be 5.9 for Chlorella (compared to an ether solution of chlorophyll a ), and of 4.5 (as compared to a methanol solution—not too different from the corresponding ratios of fluorescence lifetimes, τ_s /τ_c which were determined earlier as 3.1 and 4, respectively. The much higher values of the yield ratio, previously reported for Chlorella (about 13, compared to chlorophyll a in ether solution), may have been due to disregard of light absorption in carotenoids in live cells; and perhaps also to quenching of chlorophyll excitation by carotenoids. The latter can occur (as suggested in an earlier publication) when chlorophyll is excited to its second singlet excited state.
For Anacystis , the yield ratios were now found to be 5.1 and 3.8, when compared to ether and methanol solutions respectively; while the previously determined lifetime ratios were 3.7 and 4.9, respectively. It remains to be seen whether the remaining differences between the lifetime ratios and the yield ratios are real and significant.